Chapter 52
Evolutionary Psychology and the Law

Owen D. Jones

Forget criminal trials, speeding tickets, and plaintiffs' attorneys looking for big wins on small injuries. Forget divorce lawyers, robed judges, and antidrug legislation. These are among the many distractors for the unwary, who often miss the most important thing to understand about law. It is a tool for moving human animals to behave in ways they would not otherwise behave if left solely to their own devices. Put starkly, legal systems modify features of the human environment in order to modify human behavior. Viewed this way, law's need for evolutionary perspectives on behavior, including those from evolutionary biology and evolutionary psychology, becomes obvious. A better understanding of behavior can aid society's efforts to change behavior.

Legal systems encourage people to act in ways that further public goals. These goals obviously vary. For example, they range from controlling pollution to ensuring a minimum income for society's poorest, from facilitating a thriving economy to protecting property from theft, and from ensuring that foods and drugs are safe and effective to ensuring that important disputes are resolved without violence in fair and principled ways.

Of course, it is the rare public goal that would, if achieved, benefit all individuals in a society equally. The interests of individuals are rarely identical—and in democratic societies public goals are typically those goals that a sufficient number of individuals representing yet other individuals designate as public goals. In the end, however, legal policy makers are among the key players in soliciting, framing, articulating, and ultimately defining these varied public goals. Policy makers not only influence which goals will become top priorities, they also help to choose among possible methods for pursuing these goals.

Although methods vary considerably, they typically sort into two general categories. One category includes methods that physically force people to behave (or not to behave) in a given way. For example, incarceration, among other things, physically prevents offenders from reoffending. The other category includes methods that influence behavior less directly, by changing incentives through things such as taxes, fines, rewards, and threats of various sorts.

In general, efforts to effect a behavioral change by changing incentives rely on numerous assumptions, comprising explicit or implicit behavioral models, about where human behavior comes from, what affects it, and how. Yet, to date, with some notable exceptions, legal policy makers are either surprisingly unaware of the extent of their dependence on behavioral models or, instead, complacent in their belief that they already deploy good ones.

In either case, integrating evolutionary perspectives on human behavior can help (Jones & Goldsmith, 2005). This chapter (originally written for the previous edition of this book, but now including an update at the end, about developments over the last decade) consequently explores and illustrates a number of specific contexts in which “evolutionary analysis in law” (Jones, 1997) can prove useful.

Increasing Efficiency

At the most general level, evolutionary analysis in law can help to increase efficiency. The efficiency of legal methods in achieving legal goals by inspiring changes in human behavior depends on a robust behavioral model. In this way, and as Figure 52.1 illustrates, the efficiency of law depends on an accurate behavioral model in the same way that the efficiency of a lever depends on the solidity of its fulcrum.

Figure 52.1 The Dependence of Law on Sound Behavioral Models.

Soft fulcra are poor fulcra. Inaccurate behavioral models therefore serve as inefficient fulcra for the lever of law. Moreover, behavioral models that omit evolutionary perspectives are often materially inaccurate. Thus, to the extent that evolutionary processes influence human behavioral predispositions, a robust behavioral model should incorporate evolutionary perspectives. More specifically, if improving behavioral models can yield more effective legal tools, and if human behavior is influenced by evolutionary processes, then greater knowledge of how evolutionary processes influence human behavior may improve law's ability to regulate it.

Discovering Useful Patterns in Regulable Behavior

Because data neither self-collect nor self-organize, discovering patterns in data often requires some theory that suggests what data to collect and what aspects of the data to cross-correlate. Evolutionary analysis can often serve as one source of theories to help us collect and collate data in pattern-revealing ways relevant to law.

For example, there is a vast literature in animal behavior on infanticide (Hausfater & Hrdy, 1984; Jones, 1997, includes an overview). Natural selection appears to have favored, in many species, the selective elimination of unweaned infants by unrelated males in a position to mate with the mother. Nursing has a contraceptive effect (which apparently functions to adaptively regulate the interbirth interval), and the death of the infant speeds the mother's return to an impregnable state. This affords material advantage to the selectively infanticidal male, and the great risk to unweaned infants drops off commensurately at weaning age, when the juvenile impinges less directly on its mother's impregnability.

The evolutionary analysis of this pattern in other species suggested to psychologists Daly and Wilson (1988) that a similar pattern may occur in human populations. It does. Although the contraceptive effect of nursing is somewhat less pronounced in humans, Daly and Wilson found an extremely elevated risk of death to an unweaned infant (roughly a 100-fold increase) in the presence of unrelated males, and a similarly precipitous drop in risk at weaning age. It is important that, although there was some general assumption of increased risk, neither the magnitude of the risk nor the sudden change in risk at weaning age was previously appreciated, largely because data on relevant variables (e.g., the presence or absence of genetic relatedness) were often uncollected.

The point here is not that stepparents of dead infants should be considered guilty until proven innocent. The point is that through political processes, the legal system is presently tasked, in part, with helping to improve ways for investigating and preventing child abuse and infanticide. And it could do this, in part, by directing limited resources toward child protective services agencies, helping to fund data collection efforts, helping to specify variables on which data should be collected, and aiding in the creation of effective protocols for prioritizing and investigating rumors of abuse that may precede serious injuries.

Consequently, a theory that could influence data collection in ways leading to the discovery that stepparents are roughly 100 times more likely to kill an infant than genetic parents would seem extremely useful in achieving maximum prevention. And there are probably many other law-relevant patterns that evolutionary analysis can help reveal. These might arise from contexts pertinent to spousal abuse, homicide, marriage patterns, family size and composition patterns, deviations from rational choice predictions, and the like, to name a few.

Uncovering Policy Conflicts

Evolutionary perspectives cannot by themselves justify what law should do. For instance, the fact that stepparents not only kill but also abuse their stepchildren at far higher rates per capita than do parents says precisely nothing about whether the law should take stepparentage into account in any way (as it might do, for example, in specifying investigation protocols for child protective services agencies having limited investigative resources).

Nonetheless, one use for evolutionary analysis is to identify previously underrecognized policy conflicts. Consider, for example, the seemingly unrelated goals of destigmatizing stepparentage, on one hand, and reducing infant deaths, on the other. Evolutionary analysis, by itself, has no bearing on which of these two goals should be deemed the higher priority. But it can suggest that success in pursuing either goal may importantly trade against success in pursuing the other. Revealing such trade-offs in law may aid our efforts to lessen them—because seeing a potential policy conflict is the first step in resolving it.

Sharpening Cost-Benefit Analyses

We know that when a legislature allocates funds to build a tunnel or fails to prohibit its governed from driving cars, people will die. But we consider the benefits worth the costs. Although there is much legitimate debate about the contexts in which cost-benefit analysis may be useful, one thing is clear. Whenever it is used, inaccurate tallies will improperly skew results.

When evolutionary analysis reveals hidden policy contexts, it also offers collateral benefits, in that it helps to clarify and quantify the trade-offs involved in simultaneously pursuing two different legal goals that conflict. For example, evolutionary analysis suggests that one cost of moving aggressively to reduce infanticide and child abuse may be the collateral stigmatization of all stepparents due to the actions of only a fraction. Correspondingly, the cost protecting stepparents from such stigmatization may include some number of otherwise preventable infant deaths or child injuries.

Clarifying Causal Links

Because causality cannot be inferred from data alone, we are typically hesitant to base legal policies on mere correlations lacking explanations. Consequently, one role for evolutionary analysis in law concerns the development and support of causal theories that trace an understandable pathway between correlated phenomena.

For example, even if we strongly suspected that stepparents were more likely per capita to abuse stepchildren than were genetic parents, we would have good reason not to act on that suspicion. Our observations may be skewed as a function of prejudice. Our righteous zeal to aid children might lead to scapegoating vulnerable targets. And our collective history in oversimplifying complex phenomena should give us proper pause. There may be complicating confounds.

But consider how evolutionary analysis offers two things. First, it details a pathway by which natural selection can favor condition-dependent male behavioral predispositions that can yield fatal abuse of unweaned offspring of potential mates. Second, it connects empirical data on infanticide in humans and nonhumans. In such cases, and even when evolutionary analysis might not itself lead to discoveries of new patterns, its frequent ability to provide robust explanations for correlations can make an important difference in legal policy. It can help to provide the logical foundation that serves as an important prerequisite to establishing legal policies that are both efficacious and reasonable.

Providing Theoretical Foundation and Potential Predictive Power

Evolutionary analysis can sometimes provide theoretical foundation for known behavioral data lacking coherence, and thus serve to help predict undiscovered patterns in human behavior (Jones, 2001d). Consider, for example, that large body of literature known as behavioral law and economics (BLE). Eschewing traditional law and economics approaches, scholars of BLE seek to incorporate insights from cognitive psychology (of the Tversky and Kahneman heuristics and biases kind; Tversky & Kahneman, 1982). Their efforts are aimed at understanding apparent deviations of human behavior from neoclassical economic rationality predictions. Examples follow, but the key point is that humans often behave in ways that seem substantively irrational, and BLE scholars would like law to take account of these deviations. The law generally assumes—particularly when estimating the efficiency properties of rules—that people will not make routine errors in their attempts to maximize their utility. And if that assumption is wrong, then laws based on it may be flawed.

On one hand, the BLE movement usefully draws attention to the ways in which real people behave differently from theoretical people. And this is obviously useful for policy makers. On the other hand, the BLE scholars are presently far better at detailing that people behave in manners inconsistent with various rational choice predictions than they are at explaining why they do so (Jones, in press). And that why is the key to a theoretical foundation sufficiently robust to aid predictions about undiscovered patterns. By way of illustration, consider three seemingly irrational biases, and the problems they pose for law.

Rational choice theorists assume that people deploy rationally appropriate “discount rates” when evaluating the future. For example, a dollar to be received 5 years from now should be discounted, compared to a dollar received today, at a rate that reflects reasonable expectations for inflation. Yet people often employ absurdly high discount rates. For example, they often underinsulate their homes, even though the cost of adding insulation will be earned back in energy savings within a very short time (Ulen, 1994). That is, they act as if inflation will be enormously high over the next few years (between 45% and 300%, by some estimates, when energy-saving appliances are at issue; Ulen, 1994) such that the large money they save in energy efficiency in the future will be worth less than the small amount they save today in purchasing less insulation. The existence of seemingly oversteep discounting has important legal implications. These include, for example, matters as diverse as discouraging needless pollution and encouraging appropriate savings for retirement.

Rational choice theorists also assume that people will base their choices on realistic assessments of probabilities. But people routinely make gross errors in assessing probability. For example, they often fail to recognize that an activity posing a .7 risk of death is more dangerous than an activity in which 6 out of 10 people participating will die (Slovic, Fischhoff, & Lichtenstein, 1982). This error has important consequences for legal policies concerning risk regulation.

Rational choice theorists assume that people will value property sensibly and consistently. For example, the difference between an individual's maximum willingness to pay for a good or legal right and the minimum compensation that individual would demand to willingly sell it should be negligible. But often it is not. Experiments indicate that people often value something they have just received at a higher amount than they would have been willing to pay for it (E. Hoffman & Spitzer, 1993). This phenomenon, often referred to as an endowment effect, has important consequences for the legal distribution of entitlements. For example, and as with goods, the end distribution of various legal rights should be insensitive to the initial distribution (at least when information and transaction costs are low) because the party who values the right more will simply purchase the right from the party who values it less (Jones & Brosnan, 2008), leaving the end result economically efficient, regardless of to whom the legal system initially gives the right. But the existence of endowment effects suggests that, in sharp contrast, the initial distribution of rights will be “sticky,” because those who receive them first will suddenly value those rights more than they would have been willing to pay for them in the first place, which may leave the end result inefficient.

These legally relevant irrationalities, and others like them, are presently thought to arise from some peculiar combination of bounded rationality and (in these oft-used terms) cognitive fallibilities, frailties, flaws, errors, defects, quirks, limitations, and imperfections (Jones, 2001d). Bounded rationality describes deviations from rational choice predictions as the result of (a) constraints on time and energy for gathering perfect information and (b) constraints on the brain's information capacities, wiring, and computing speed (Simon, 1990).

But even a moment's reflection makes clear that this approach is unsatisfactory. There is no theoretical framework that explains the patterns of irrationalities, connects them together, and points in new directions. For example, why do people apparently tend to overdiscount the future, rather than to underdiscount it or to discount it randomly? Why do people apparently tend to overendow goods, rather than to underendow goods or to endow goods randomly?

A number of people have independently explored these and related phenomena from evolutionary angles. There are at least three approaches. Gigerenzer (1991, 1998; Gigerenzer, Todd, & The ABC Research Group, 1999) developed the idea of “ecological rationality,” which considers some seeming irrationalities as artifacts of experimental designs. For instance, mistaken probability assessments may follow from information about risk being presented in the format of modern statistics, rather than the more natural format of frequency distributions. Haselton and Buss (2000, 2003) developed “error management theory,” which suggests that biases leading to error can evolve from the effects of evolutionary processes responsive to the asymmetric costs of false positives and false negatives, when attempting to infer the intentions of others. For instance, asymmetries between the sexes in minimum investment in offspring and maximum lifetime number of offspring can ultimately lead to male overperception of female sexual interest and female underperception of male commitment. My own work (Jones, 1999a, 2001b, 2001d) develops the concept of “time-shifted rationality,” which considers much of what gets lumped under the umbrellas of bounded rationality and cognitive quirks to reflect finely tuned cognitive adaptations to environments lacking the modern features (such as highly abstract notions of legally enforceable rights to resources) that render them irrational in the present era. For instance, viewed in the context of ancestral environments, endowment effects may reflect an adaptive bias to keeping a less preferred but certain resource already possessed, instead of risking uncertain performance of an offered exchange for a more valued item.

These three evolutionary approaches—focusing on ecological rationality, error management, and time-shifted rationality—emphasize different aspects of various cognitive puzzles but are nonetheless compatible. Whether joined or used separately, the perspectives on human irrationalities that these three approaches offer hold some significant promise, in the legal arena, of providing theoretical foundation to patterns in existing anomalies and helping to predict undiscovered patterns.

Assessing Comparative Effectiveness of Legal Strategies

Time-shifted rationality—the propensity toward behavior that was adaptive in ancestral environments, even if it is irrational or counterproductive in novel current environments—also has a role to play in helping us compare probable effectiveness of differing legal approaches to changing people's behaviors.

We know that, with some exceptions, the demand for a given good will tend to go down as the price for that good goes up. The general relationship between changing price and changing demand is commonly represented graphically by a “demand curve” (often portrayed for simplicity by a straight line, with price on the vertical axis; see Figure 52.2).

Figure 52.2 General Assumption in Law About the Relationship Between the Incidence of a Behavior and the Cost of That Behavior.

We also know that behaviors have their own demand curves. Increase the “price” of engaging in a behavior, by increasing the associated fine or the prison term, for example, and generally the incidence of that behavior will decrease (holding constant the probabilities that an offender will be detected, apprehended, and subjected to penalty).

The problem is that we know very little about the precise relationship between increased prices and decreased incidence of behavior, except from trial, error, and intuition. Because sanctions are themselves costly to administer, we would benefit from having some sense, ahead of time, of the likely return on our investment in sanctions. Specifically, we would like some sense of how much of a decrease in undesirable behavior are we buying with each increment of increased penalty?

Figure 52.3 makes the point more graphically. At one extreme, a behavior may be very responsive to increases in sanctions, so that a relatively small increase in price yields a big decrease in behavior. The demand curve for such a behavior may look like the more horizontal curve A. Or, at the other extreme, a behavior may be relatively insensitive to increases in sanctions, so that a very large increase in sanctions is necessary to achieve even a modest decrease in behavior. The demand curve for such a behavior may look like the more vertical curve B.¹ Holding the probabilities of detection, apprehension, and penalty constant, the curve for some behaviors, such as jaywalking, will more closely resemble curve A. And the curve for some behaviors, such as becoming violent when coming upon a spouse engaged in adulterous sex, will more closely resemble curve B.

Figure 52.3 Variations in Responsiveness of Behavior to Increasing Cost.

Evolutionary perspectives enable us to derive a principle that can help legal thinkers anticipate in general terms the comparative sensitivities of various human behaviors to changes in incentives effected with legal tools. That principle helps not only to explain but also to predict differences in the relative steepness of demand curves for, and hence the comparative sensitivities of, different behaviors.

I call that principle the law of law's leverage (Jones 1999a, 2000, 2001b, 2001d). It predicts that

The magnitude of legal intervention necessary to reduce or to increase the incidence of any human behavior will correlate positively or negatively, respectively, with the extent to which a predisposition contributing to that behavior was adaptive for its bearers, on average, in past environments.

Here is what the terms mean.

“Magnitude of legal intervention” refers, in most instances, to costliness. Greater resistance to change will increase the cost of effecting change. “The extent to which” a predisposition contributing to the behavior was adaptive to its bearers underscores the fact that while members of a species share a variety of different adaptations, some (such as hunger) are comparatively more important than others (such as the capacity for empathy). “A predisposition” refers to a psychological trait that is a heritable and behavior-biasing algorithm manifested in the brain's neural architecture. For a behavioral predisposition to be “adaptive,” it must have conferred greater fitness benefits on individuals that bore it than did any other contemporaneously existing alternatives exhibited by other individuals within the population, and thus have been maintained by natural selection. Genetic fitness is measured in terms of inclusive fitness (rather than simply offspring) taking into account degrees of consanguinity. The term “on average” in the law of law's leverage refers to whether the cumulated effects of the adaptation, across all the organisms that bore it, yielded increases in inclusive fitness that outweighed any decreases. That is, on average the trait increased the reproductive success of organisms that bore it. “Past environments” refers to the environment of evolutionary adaptedness (EEA). The relevant EEA varies from feature to feature.

Consequently, a more detailed and accurate (if also more cumbersome) rephrasing is this: The law of law's leverage states that the magnitude of legal intervention necessary to reduce or to increase the incidence of any human behavior will correlate positively or negatively, respectively, with the extent to which a behavior-biasing, information-processing predisposition underlying that behavior (a) increased the inclusive fitness of those bearing the predisposition, on average, more than it decreased it, across all those bearing the predisposition, in the environment in which it evolved and (b) increased the inclusive fitness of those bearing the predisposition more, on average, than did any other alternative predisposition that happened to appear in the environment during the same period.

This law of law's leverage predicts that, typically, it will be less costly to shift a behavior in ways that tended to increase reproductive success in ancestral environments (measured in inclusive fitness) than it will be to shift behavior in ways that tended to decrease reproductive success in ancestral environments. In other words, the slope of the demand curve for historically adaptive behavior that is now deemed undesirable will be far steeper (reflecting less sensitivity to price) than the corresponding slope for behavior that was comparatively less adaptive in ancestral environments. This rule will tend to hold, even when the costs that an individual actually and foreseeably incurs in behaving in a historically adaptive way vastly exceed the presently foreseeable benefits of such behavior.

Consequently, the law of law's leverage predicts that in criminal law, family law, torts, property, and the like, behaviors involving the following things will prove more difficult to modify than the behavior of median difficulty: mating, fairness, homicide, child rearing, status seeking, property and territory, resource accumulation, sexuality (including infidelity and jealousy), speech, privacy, empathy, crimes of passion, moralistic aggression, risk valuation and risk taking, cooperative/altruistic behavior, male mate-guarding, and the like.

Here (largely from Jones, 2001d) are several examples:

• Evolutionary analysis predicts that, and explains why, the slope of the demand curve for adulterous behavior (like most sexual behavior) is likely to be comparatively steep (Buss 1999a, 1999b, 2000) and thus comparatively insensitive to the imposition of legal prohibitions.
• Evolutionary analysis also predicts that, and may help explain why, marriage, separation, divorce, and remarriage behavior will be less sensitive to legal changes than will be many other forms of behavior (Ellman & Lohr, 1998; Fisher, 1994).
• Because, as we know, natural selection disfavors inbreeding among close relatives (Goldsmith, 1994; Goldsmith & Zimmerman, 2000), evolutionary analysis predicts that it will be far less costly to achieve a given low rate of incest per capita between a parent and his or her natural children, and among siblings reared together, than to achieve the same low rate of incest per capita between stepparents and stepchildren, and among stepchildren.
• Because we know that natural selection favors discriminative parental solicitude rather than indiscriminate parental solicitude (i.e., it generally favors psychological mechanisms that bias resources toward offspring over nonoffspring; Daly & Wilson, 1995), we can predict that men under court order to provide child support payments for a child they know or suspect they did not father will be less likely to comply, on average, than will biological fathers (Wilson, 1987).
• Because we know that threats to status within a social group impose particularly large costs across evolutionary time (Daly & Wilson, 1988; Buss & Shackelford, 1997), we can predict that the slope of the demand curve for violence consequent to status threats will be steeper than that for most other proscribable behavior, and will be particularly steep in public.
• Because we know that the asymmetries for males and females of internally fertilizing species in the consequences of a partner having sex with a third party favored sexual proprietariness in males more strongly than in females (because only males can be uncertain of their genetic relationship to their putative children), we can predict that the slope of the demand curve for jealous violence (against rivals, or straying partners) will be steeper, on average, for males than for females (Buss, 2000).

Obviously, the law of law's leverage can neither predict demand curves for law-relevant behaviors with precision, nor can it individualize a curve to a single person. Moreover, statements about relative aggregate costs do not translate neatly into conclusions about cost effectiveness. Nonetheless, the law of law's leverage can offer some broad, novel, and useful insights into the differing ways law and behavior interact, depending on the behavior at issue. Because we understand that the brain tends to process information in ways that tended to yield adaptive solutions to problems encountered in the environment of evolutionary adaptedness, we can expect that behavioral inclinations will tend in turn to vary in their susceptibility to the influence of different legal tools. The principle can afford us more intellectual traction than we now have on predicting the comparative slopes of the demand curves. It can thereby afford additional information useful to estimating the relative costs to society of attempting to move different kinds of behavior. The principle also provides a new and powerful tool for explaining and predicting many of the existing and future architectures of legal systems—which is the subject of the next section.

Revealing Deep Patterns in Legal Architecture

Much has been said over the years about why human cultures generally, including legal cultures specifically, vary from place to place. But we have traditionally lacked comprehensive theories about the contexts in which we might expect legal cultures to be similar (e.g., what is punished or encouraged, and how) and why we might expect similarities. Evolutionary analysis can provide some of the framework for the development of such theories.

The logic proceeds this way. Because humans share an evolved, species-typical neural architecture, they in turn share a species-typical repertoire of emotions and behavioral predispositions (Barkow, Cosmides, & Tooby, 1992; Buss, 1999b; Goldsmith, 1994; Goldsmith & Zimmerman, 2000; Pinker, 2002). To the extent that legal systems are sensitive, in part, to the emotions and behavioral predispositions of a governed population, we may expect and predict that legal systems across time and across the world's cultures will tend to have nonrandom similarities in a variety of their major features. That is, because legal systems are both aspects of human behavior and societal responses to human behavior, and because evolutionary processes influence human behavior, we should expect to see the telltale results of evolutionary processes in legal systems.

There will be differences, of course. But we may expect that the architecture of human legal systems will, despite their differences, reflect the effects of evolutionary processes on the human brain, just as (in an example from Dawkins, 1989) the architecture of beaver dams, despite their differences, reflects the effects of evolutionary process on beaver brains.

Many scholars took intriguing initial steps in this direction (Alexander, 1979, 1987; Beckstrom, 1989; Gruter, 1977; Gruter & Bohannan, 1983; Wilson, 1987). I have attempted to build on that thinking—to describe possible foundations for what I call biolegal history (Jones, 2001c). And over the past decade (see the chapter-ending update later) there has been some exciting new work to report. In the meantime, and for general orientation, one way of looking at this is to consider how the main design features of legal systems can be described with four variables: topics, content, tools, and effort.

In brief, topics are the general subject matters that legal systems address (e.g., sexual behavior or access to resources). Content reflects the specific normative preferences people in policy-influencing positions tend to have about those subject matters (e.g., minors should be protected from sex with adults, and one person should not take resources from another without justification). Tools is a set that includes all methods potentially available to legal systems to bring reality into line with the normative preferences (e.g., incarceration or fines). Effort reflects the potential variation—from trivially easy to insurmountably difficult—in how difficult it may be to effect such change using any particular method.

We can roughly approximate some of the superstructure of legal systems—in ways that allow rough but potentially useful comparisons—by sketching together the specific topics, content, tools, and effort of which each system is composed. Evolutionary analysis, including both the ways in which evolutionary processes affect morality (topics and content; Alexander, 1987; Jones, 1999b, 2000) and the ways in which evolutionary processes affect the comparative difficulties law will have moving some behaviors with some methods compared to others (tools and effort), strongly suggests that superstructural patterns of legal systems will not vary randomly across cultures.

As in so many other contexts in which human behavior is examined, the very existence of variation can yield initial conclusions that differences outweigh similarities. I suspect much the same will be true as our knowledge of different legal systems across the world's many cultures increases. But legal systems should ideally be compared not just to each other (a technique that frequently highlights difference) but also to the possible legal architectures that the overall design space would allow—were the features of legal systems comparatively randomly distributed.

Evolutionary analysis predicts that, when viewed from this greater distance, legal systems will be rather clumped in one small sector of the overall design space. That is, evolutionary analysis suggests that a given legal architecture will not be—as often assumed—simply an amalgam of culture-specific norms, culture-specific religions, culture-specific morals, culture-specific politics, and general economic efficiencies. An evolutionary perspective provides a far different sense of the prior probabilities that various legal systems will have the structural elements they do.

Although this has recently begun to change, relatively little is known about how the propensities among all the world's many societies to govern selves and others with rules, laws, and other forms of legal behavior compare. Although there are some notable commonalities (e.g., proscriptions against the unjustified taking of human life; Brown, 1991), there has been until recently (see below) little work to systematically compare the legal cultures of large numbers of different human societies. Some cultures obviously have very formal legal structures, with copious and minutely detailed statutes, as well as extensive judiciaries and dedicated academies. In other cultures, behavior is regulated principally by less formal but highly significant social controls—such as ostracism—operating within relatively small groups. But in all cases evolutionists would expect that the need to establish norms for proper behavior and the need for enforcing such norms will tend to reflect the evolved features of the human brain, as will the patterns in which these needs are satisfied. Evolutionary perspectives on legal behavior may therefore help us acquire a richer and more coherent sense of the deep structure of human legal systems shared cross-culturally.

Exposing Unwarranted Assumptions

Evolutionary thinking can often supply, in Dennett's (1995) term, a “universal acid” for dissolving untenable ideas. This is as important a function to perform in law as it is elsewhere. Because if reliance on flawed assumptions about the causes of a given behavior are wrong, and evolutionary analysis can help to reveal this, we can minimize the effects of flawed legal approaches and get on with the business of pursuing more effective ones.

A good example comes from the law's various approaches to curbing sexual aggression. Few things warrant greater efforts. Yet different legal approaches have been based, over time, on very markedly different theories of where sexual aggression comes from. An early psychiatric theory led to legal regimes predicated on the notion that rapists are crazy people. Subsequently, a sociological emphasis led to regimes predicated on the idea that rapists are conditioned into being rapists by their sociocultural milieu. And the influence of later feminist theories led, in part, to anti-sexual-violence statutes reflecting the assumption that a cross-sex rape is simply a crime of gender hatred, just as a cross-race lynching is a crime of racial hatred.

Rape is an important and delicate topic, which I have explored elsewhere at length (e.g., Jones, 1999c). Its very existence is a reminder of how disinhibiting the aggressive exercise of power can foster fear, impede female autonomy, and improperly restrain women's bodies, lives, and opportunities. But clearly our inability to eliminate rape, with the various tools available to law, strongly suggests that our understanding of the phenomenon is imperfect.

No single discipline, probably, can alone supply a complete model of the phenomenon. Yet, a thorough grounding in both general evolutionary studies and in the many studies of patterns of sexual aggression in humans and in the many other species in which sexual aggression occurs (see, e.g., studies cited in Jones, 1999c, Appendix A) suggests that at least one thing is intellectually untenable. It is incorrect to assume—as has been done so often that people now mistakenly confuse preference with fact—that sexual desire is entirely irrelevant to sexual aggression.

Specifically, a thorough and detailed study of hypotheses and evidence concerning sexual aggression in the many other species in which it occurs, and in the many distinct patterns in which it appears, suggests that evolutionary processes have had an important influence on patterns of human sexual aggression, just as they have had important influence on other patterns of conflict. The patterns of sexual aggression in other species are simply too numerous, too consonant, and too distinct. And the near identity of those patterns, in relevant respects, with human data on sexual aggression is striking (Jones, 1999c).

The point here, though, is not that evolutionary analysis alone provides useful perspectives on rape phenomena. The point is that evolutionary analysis is often an essential part of any complete picture of human behavior. While causes of any individual's act of sexual aggression can vary, it is simply illogical to assume that the effects of evolutionary processes on the biology of sexual desire are irrelevant to patterns of human sexual aggression. Even a minimum facility in behavioral biology can help to disclose why such an assumption, as well as many similar assumptions in other legal contexts, no matter how well intentioned, are likely unwarranted and also likely to send legal policies in inefficient directions.

Disentangling Multiple Causes

Evolutionary analysis in law highlights the distinction between, and essential complementarity of, different levels (proximate and ultimate) of causation. In the context of sexual aggression, for example, this encourages us to look beyond falsely dichotomous thinking, and to recognize that the clear existence of environmental factors that influence probabilities of sexual aggression in no way diminishes the role of evolutionary processes in associating those environmental factors with the behavioral repertoires specific to sexual aggression.

Increasing Accuracy

Generally speaking, accuracy is better than inaccuracy. And incorporating evolutionary perspectives into legal thinking will, on many occasions, help to increase accuracy.

There are two principal ways in which legal thinking may reflect inaccurate assumptions. One is to be flat-out wrong. For example, suppose that those charged with developing a legal approach to reducing the incidence of aggression assumed that aggression in humans is entirely socioculturally determined. That assumption, as best as we can know, is simply wrong. The body of evidence, and the robustness of corresponding theory, supporting the existence of evolutionary effects on patterns of aggression is overwhelming, compared to evidence to the contrary.

The other way to be inaccurate is through incompleteness. Incompleteness often contributes to inaccuracy in the form of misplaced emphasis. For example, suppose those charged with reducing the incidence of aggression were agnostic on whether there were evolutionary influences on patterns of human aggression, but their approach ultimately reflected attention only to sociocultural contributions to patterns of aggression. The overwhelming evidence that aggression is affected both by environmental inputs and by the ways in which corporeal brains have evolved to associate certain patterns of environmental inputs with psychological states tending to increase or decrease aggression renders such a legal approach inaccurate through incompleteness.

To be clear, I am not advocating reflexive deference to the evolutionary sciences. For one thing, no scientific principles are categorically beyond legitimate challenge. And, more importantly, there may be times when what it costs (in time, money, misunderstandings, or misuse) to increase accuracy is far greater than the payoff at the other end (Jones, 2004; Ulen, 2001). For legal systems are not just about a search for truth (though they are often about that). Frequently, legal systems are tasked with getting the most bang, measured in desired human behavioral changes, for the fewest bucks—bucks not being infinite. Consequently, for example, a policy based on assumptions that are 80% accurate, and which is ultimately 70% effective, may be preferable to one that is 98% accurate, 98% effective, and 6 times as costly.

There may therefore be, on occasion, justification for knowingly choosing to accommodate inaccuracy in behavioral models. But the point here is that to knowingly engage in a fiction without an affirmative and justifiable decision to do so is to improperly privilege flawed approaches.

Increasing Law-Relevant Understanding About People

Aside from all the many policy-level benefits of blending evolutionary insights into the legal system's approaches toward influencing human behaviors, evolutionary thinking has street value in a number of practical, frontline contexts. For example, good lawyers understand people. They have a good sense of what motivates people and how those motivations translate into behavior relevant to the legal system, such as obeying or disobeying laws, initiating or settling lawsuits, and the like.

Evolutionary perspectives are often useful in this context. Consider litigation. Traditional economic theory predicts that a plaintiff will pursue litigation as long as the potential recovery, multiplied by the probability of success, exceeds foreseeable litigation costs. But real people often do not behave this way, and much litigation behavior is pursued at some cost in order to impose a greater cost on another.

To those with an evolutionary lens, this behavior is not surprising. Our brains did not evolve solely as temporally narrow cost-benefit maximizing machines. And there are at least two pathways by which such costly but cost-inflicting behavior can have evolved.

First, retributive spitefulness can be a component of a mixed, evolutionarily stable strategy for reaping gains from cooperation and punishing defectors. Even when spiteful behavior is unlikely to yield compensating advantages in future interactions with others, as a function of current reputational effects (Frank, 1988), our evolved behavioral predispositions may incline us toward spiteful behavior because of its adaptive effect on local reputation in ancestral environments. Second, behaviors that impose greater costs on competitors than on selves can evolve straightforwardly, even in the absence of retributive predispositions, because a decrease in absolute status or condition that nonetheless results in an increase in relative status or condition yields evolutionary gains.

Just as lawyers ignorant of human emotions are likely to be poor lawyers, lawyers ignorant of the effects of evolutionary processes on human psychology are likely, in many contexts, to be less effective than they might be otherwise. The ability of evolutionary perspectives to offer new and useful insights into human psychology can therefore render those perspectives both important and advantageous.

Generating New Research Questions

Notably, this cross-fertilization of evolutionary and legal disciplines need not be unidirectional. If there are a number of advantages for legal thinking in learning more about evolutionary processes from evolutionists, there are at least three advantages for evolutionists in learning more about law.

The first advantage arises from the ability of law to represent an area of applied evolutionary analysis. While knowledge generation is a worthy goal in itself, comparatively little attention has focused on the utility of evolutionary perspectives on human behavior. Just as Darwinian medicine (Nesse & Williams, 1996) represents a useful application of evolutionary knowledge in health contexts, so can evolutionary analysis in law offer new opportunities for application in legal contexts. The advantage for evolutionists, then, is that the wide variety of things useful for legal thinkers to know can help to generate important researchable questions and to open up new areas of research for evolutionists in search of new research frontiers.

The second advantage, and one apparently first articulated by Beckstrom (1989), is that legal databases contain more than 10 million reported cases (in full on-line texts with Boolean searching) that together can serve as accumulated observational data for testing evolutionary hypotheses. Moreover, the variation in the legal environments of the 50 states yields virtually untapped data from 50 natural laboratories.

The third advantage is the opportunity to analyze the work of legal actors themselves within evolutionary frameworks. For law not only deals in human behavior, it is human behavior. And the behaviors of judges, legislators, lawyers, police, and the like have yet to be examined systematically from an evolutionary perspective. For example, the way people with effective influence over law actually wield that influence likely reflects condition-dependent predispositions sensitive to relative power and status, which in turn influence their goals and behaviors.

Conclusions

Let's take stock. By integrating evolutionary insights into legal thinking, both legal policy makers and evolutionists can help to:

• Increase efficiency.
• Discover useful patterns in regulable behavior.
• Uncover policy conflicts.
• Sharpen cost-benefit analyses.
• Clarify causal links.
• Provide theoretical foundation and potential predictive power.
• Assess comparative effectiveness of legal strategies.
• Reveal deep patterns in legal architecture.
• Expose unwarranted assumptions.
• Disentangle multiple causes.
• Increase accuracy.
• Increase law-relevant understanding about people.
• Generate new research questions.

Each of the preceding examples of the usefulness of evolutionary analysis in law could alone justify focused integration of evolutionary sciences into behavioral models essential to sound legal thinking. Viewed together, they make an even more powerful, geometrically stronger case (Jones & Goldsmith, 2005). What, then, might serve to delay?

There are a number of obstacles. For instance, few legal thinkers have either strong backgrounds or interests in science—so ability and enthusiasm are often lacking. Few understand the distinction between proximate and ultimate causation in biology (particularly since the former term bears a different meaning in biology than it bears in law). Consequently, false dichotomization of social and biological influences is common. Condition dependence, and the evolution of algorithmic predispositions, are widely unrecognized. Consequently, the more subtle, environmentally sensitive dimensions of behavioral biology get overlooked.

All of these factors lead to, among other misperceptions (described in Jones, 1999c, 2001a), ascription of genetically deterministic viewpoints, defense of the supposed categorical boundary between meaningful human behavior and the behavior of all other species, and the assumption that discussion in law of evolved behavioral predispositions could prove useful only in the contexts of genetic defenses in criminal trials. The latter both reflects and then reinforces the fear that proponents of evolutionary analysis in law will try to use explanation as justification.

This assumption is, of course, mostly nonsense. And it stems not merely from healthy skepticism, or even from an appropriate and constructive caution concerning all things biobehavioral that traces to the historical misuses of biology in both politics and in law (e.g., Buck v. Bell, 1927). Instead, it stems largely from the cultural gap between scientists and nonscientists, the obsolete overdivision within universities of human and nonhuman species, and the general time lag between the advances in scientific arenas and their recognition and understanding in legal arenas.

Many have argued—albeit in differing ways—for the potential value to law of evolutionary perspectives. A sampling of works spanning the first 25 years includes (in chronological order): Gruter, 1979; Gruter & Bohannan, 1983; Beckstrom,1985; Gruter & Masters, 1986; Stake, 1990; Rodgers, 1993; Fikentscher & McGuire, 1994; Browne, 1995; Frolik, 1996; Ruhl, 1996; Jones, 1997; Grady & McGuire, 1997; McGinnis, 1997; Coletta, 1998; Monahan, 2000; Goodenough, 2001; Gruter & Morhenn, 2001; Elliott, 2001; O'Hara & Yarn, 2002; Jones & Goldsmith, 2005. More recent works are discussed in the next section. Together, these illustrate broad interests that have manifested in a wide variety of programs, conferences, initiatives, courses, publications, and organizations.

For example, the Gruter Institute for Law and Behavioral Research (www.gruterinstitute.org) has a long history in educating legal and evolutionary thinkers, through conferences and publications, about prospects for important work at the intersection of their disciplines. And the Society for Evolutionary Analysis in Law (SEAL; www.sealsite.org) has helped to generate engagement and scholarship through its network of several hundred interdisciplinary members spanning more than 30 countries. The prospects for integrating evolutionary insights into law consequently look bright, despite a number of significant but surmountable impediments.

The scope of law is vast. The flow of resources, the protection of the citizenry, the regulation of risks, the funding of scientific research, the protection of ideas, the regulation of sexual, mating, and reproductive behavior, the provisioning of the poor, the enforcement of promises, the allocation of rights and duties, the resolution of disputes, the expenditure of collected taxes, and many, many other things are all inextricably intertwined in the extensive networks of legal systems.

Throughout these networks, however, the underrecognized but fundamental relationship between law and behavior remains constant: Society uses law as a tool for moving human behavior in directions it would not otherwise go on its own. And it is embedded in that pragmatic use that law's frequent need for evolutionary analysis is most clear. A competent model of human behavior is essential to wringing maximum effectiveness from legal systems. And evolutionary perspectives, in turn, can frequently strengthen law's models of human behavior. The many examples this chapter has explored doubtlessly represent but a fraction of the many possible applications of evolutionary analysis in law.

The Past Decade: An Update

Commensurate with the rapid growth of empirical and conceptual work in evolutionary psychology, the last decade witnessed not only the extension of evolutionary analysis in law by scholars already in the field, but also the addition of many new scholars, with many important new ideas.

The new empirical work both strengthened foundations of, and added support to, conceptual advances at the law/evolution intersection. In addition, scholars developed and deployed evolutionary analyses in a number of new legal domains. Although it is not possible in the supplemental space afforded here to mention every new work (for more, see the bibliography I've compiled at www.sealsite.org), I provide below an overview, some observations about patterns in the field, and brief comments on future directions.

Much recent work has centered on the evolutionary underpinnings of law, which goes variously by the names of “biolegal history” (Jones, 2001d; Jones & Goldsmith, 2005), “law instincts” (Stake, 2004; Guttentag, 2009), “deep structure of law” (Kar, 2006), “moral grammar” (Mikhail, 2007), “universal moralities” (Kuklin, 2009), and “the origins of justice” (Robinson, Kurzban, & Jones, 2007), among others (Arruñada, 2008). The core idea is that legal systems reflect evolved features of the distinctly human brain. Kar, for example, uses evolutionary insights to identify complex but subtle categories of law-relevant social behavior, such as the source of the sense of obligation, how legal systems emerge and stabilize, and how a more universal sense of respect for human rights and international law might be promoted (2006, 2012a, 2012b, 2012c, 2013). Guttentag (2009) argues that the propensity to create law-like structures is itself an evolved adaptation, such that reliance on legal systems to organize social activity is an integral part of human nature. Mikhail (2011) draws on philosophy, linguistics, and cognitive science to discover and explain law's patterns. And a number of scholars have explored implications for the field of Comparative Law (De Coninck, 2010; Du Laing, 2011; Du Laing & De Coninck, 2011; Gommer, 2011a; Goodenough, 2011; Mikhail, 2009; Wangenheim, 2010).

Much interest in the evolutionary underpinnings of law focuses specifically on the criminal justice domain. For instance, Robinson, Kurzban, and Jones (2007) provided theoretical foundation, rooted in evolved adaptations, for the origins of widely shared intuitions of justice. In a book and series of papers, Hoffman and Goldsmith have provided detailed analyses of the biological roots of punishment and influences on judging (e.g., M. Hoffman, 2011, 2014; M. Hoffman & Goldsmith, 2004). And a burgeoning literature applies evolutionary analyses in contexts of condemnation (DeScioli & Kurzban, 2009, 2013; DeScioli, Gilbert, & Kurzban, 2012), revenge (McCullough, Kurzban, & Tabak, 2013), and reconciliation (McCullough et al., 2013; Petersen, 2013; Petersen, Sell, Tooby, & Cosmides, 2010; Petersen, Sell, Tooby, & Cosmides, 2012).

The past decade has seen increased evolutionary analysis in the four legal fields traditionally considered foundational to others. In the field of Property, for example, Stake (2004, 2009) and Krier (2009) have explored evolutionary underpinnings of the sense of property, in light of the significance of resource acquisition, while Jones, Brosnan, and colleagues have explored the evolutionary origins of law-relevant psychological biases pertaining to ownership, by testing in chimpanzees and orangutans narrow and unique predictions about the so-called “endowment effect” (Brosnan et al., 2007; Jones & Brosnan, 2008; Brosnan, Jones, Gardner, Lambeth, & Schapiro, 2012; Flemming, Jones, Mayo, Stoinski, & Brosnan, 2012). Applications in Criminal Law by Buss and others (Benforado, 2010; Blumoff, 2014; Broussard, 2012; Buss, 2005, 2012; Duntley & Shackelford, 2006, 2008; Goldstein, 2002; Kanazawa, 2008; Thomson, 2008; Walsh, 2006; Wilson, 2005) focus on the effects of evolutionary processes on behaviors that can get one into trouble with the law. In Torts (essentially, noncriminal harms) Bailey Kuklin (2006, 2008) turns to evolutionary psychology to explain common intuitive leaps regarding various legal rules, such as those concerning the rescue of those in peril. And in Contracts, several scholars have recently argued that evolutionary predispositions underlie laws regarding the enforcement of traded obligations (Alces, 2011; Fruehwald, 2009; Robinson et al., 2007; Yelpaala, 2008).

Beyond these four core legal subjects, Family Law continues to be an area of particularly rich activity (overview in Carbone & Cahn, 2009a). For example, David Herring provides evolutionary analyses of child welfare law contexts in a series of important papers (such as 2006, 2007, 2008, 2012, 2014) that raise intriguing questions about how best to avoid child maltreatment, or to improve foster care arrangements, given expected levels of parental investment by different types of kin. And in the vein pioneered by Judge and Hrdy (1992), regarding the effects of evolved sex differences on resource allocations (traceable through testamentary patterns), there has been additional work on the biology of social closeness, resource allocation among relatives, and the like (Segal & Marelich, 2011).

In addition, scholars are actively deploying evolutionary insights in the contexts of Employment Law, such as in the contexts of gender gaps in compensation, occupational segregation, and sexual harassment (Browne, 2008, 2013; Seaman, 2005, 2007; Urias, 2004); Constitutional Law (Almeida, 2014; Dodson, 2008); Corporations (Beecher-Monas, 2007; Geu, 2009; Hill & O'Hara, 2006); Intellectual Property (Gommer, 2011b; Goodenough & Decker, 2009); International Law (Kar, 2013); Environmental Law (Richardson, 2011); Antitrust (Horton, 2012, 2013); and the Law and Emotions arena (Patrick, in press).

With respect to the processes of law, there has been increasing interest in evolutionary perspectives on mediation, reconciliation, negotiation, and settlement (Goldman, 2008; Yarn & Jones, 2009), and in general techniques of persuasion in law (Ridgway, 2011; Vaughn, 2011). And there continue to be frequent invocations of evolutionary processes in law-relevant systemic (e.g., complex adaptive systems) contexts (Arruñada & Andonova, 2008; Cotter, 2005; Ruhl, 2008; Seto, 2005).

With respect to models of human decision-making relevant to law, there has been a great deal of interest in the similarities and differences between evolutionary and economic perspectives on human decision making (Carbone & Cahn, 2009b; Deakin, 2011; Epstein, 2009; Horton, 2011; Jones, in press; Jones, O'Hara O'Connor, & Stake, 2011; Wangenheim, 2010).

And a few critiques, one of them worth reading, appeared during this period. Amy Wax (2004) provides an informed and thoughtful treatment of the field, arguing that a richer understanding of both sexual selection and multi-level selection limits the predictive power of evolutionary analysis in human affairs. She therefore cautions against relying on evolutionary insights for specific legal interventions, and counsels recognition of the complex and subtle ways that evolutionary processes influence human behaviors relevant to law.

Looking at the trends of evolutionary analysis in law, several are emerging. One is the sharp and welcome rise, within the field, of empirical work (e.g., DeScioli et al., 2012; Herring, Shook, Goodkind, & Kim, 2009; Mikhail, 2009; Petersen et al., 2012). For example, Sarah Brosnan, colleagues, and I made and tested several novel and narrow predictions of the “time-shifted rationality” theory of cognitive biases, demonstrating that we could not only predict variation in the endowment effects for two different classes of objects, but we could also turn the effect on and off for the very same objects (Brosnan et al., 2007; Brosnan et al., 2012; Jones, in press; Jones & Brosnan, 2008).

Another trend, concomitant with the rapid growth of neuroimaging techniques, is the increasing overlap of evolutionary analysis in law with neuroscience (Alces, in press; Blumoff, 2010; Chen, 2008; Freeman & Goodenough, 2009; Goodenough & Tucker, 2010; Jones, Marois, Farah, & Greely, 2013; Jones, Schall, & Shen, 2014; O'Hara, 2004; Platek, Keenan, & Shackelford, 2006; Zeki & Goodenough, 2006). For example, numerous studies now illuminate the brain activities underlying punishment decisions (Buckholtz et al., 2008; Krueger , Hoffman, Walter, & Grafman, 2013; Treadway et al., 2014). This parallels the somewhat older and still growing intersection of evolution, law, and genetics (Beecher-Monas & Garcia-Rill, 2006; Jones, 2006).

Other trends include increasing attention to multi-level selection (Almeida, 2014; Wax, 2004), coevolutionary processes (Du Laing, 2011; Richerson & Boyd, 2005), and the evolutionary underpinnings of conscience, cooperation, and trust (Almeida, 2014; Du Laing, 2011; Hill & O'Hara, 2006; Kar, 2006; Parekh, 2004; Stout, 2011; Wax, 2004), as symmetrical pairs to evolved predispositions toward competition, aggression, and the like.

If I could make one prediction—or at least articulate one aspiration for the field—it would be that within a decade or two from now, the methods for studying human behavior relevant to law will have continued much further down the path of disciplinary consilience (an argument I develop more fully in Jones, in press). Because the various phenomena of human behavior do not come in tidy packages addressed to the exclusive attention of one university department or another, we should continue to integrate the disparate streams of research and knowledge until the necessarily complementary perspectives on ultimate and proximate causation—both the historical and the mechanistic processes—combine to provide a more accurate and useful understanding of human behavior.

Note

1. This discussion adopts the common convention of using variations in slope to capture the idea of variations in what, technically, are “elasticities” (by, for example, describing inelastic demand with a steeply sloped demand curve). The slope of a demand curve is the rate of change of price with demand. Elasticity is the percentage change in price divided by the percentage change in demand. It can be computed from knowledge of the slope at a given point on the curve. In comparing nonlinear demand curves for different activities, comparisons of slope must refer to comparable regions of curves.

References

1. Alces, P. (2011). A theory of contract law. New York, NY: Oxford University Press.
2. Alces, P. (in press). The moral intersection of law and neuroscience. Chicago, IL: University of Chicago Press.
3. Alexander, R. D. (1979). Darwinism and human affairs. Seattle: University of Washington Press.
4. Alexander, R. D. (1987). The biology of moral systems. New York, NY: Aldine de Gruyter.
5. Almeida, F. (2014). The emergence of constitutionalism as an evolutionary biocultural adaptation. Cardozo Public Law, Policy & Ethics Journal, 13, 1–41.
6. Arruñada, B. (2008). Human nature and institutions. In E. Brousseau & J. Glachant (Eds.), New institutional economics: A guidebook (pp. 81–99). Cambridge, England: Cambridge University Press.
7. Arruñada, B., & Andonova, V. (2008). Common law and civil law as pro-market adaptations. Washington University Journal of Law and Policy, 26, 81–130.
8. Barkow, J., Cosmides, L., & Tooby, J. (1992). The adapted mind: Evolutionary psychology and the generation of culture. New York, NY: Oxford University Press.
9. Beckstrom, J. (1985). Sociobiology and the law. Urbana: University of Illinois Press.
10. Beckstrom, J. (1989). Evolutionary jurisprudence. Urbana: University of Illinois Press.
11. Beecher-Monas, E. (2007). Marrying diversity and independence in the boardroom. Oregon Law Review, 86, 373–411.
12. Beecher-Monas, E., & Garcia-Rill, E. (2006). Genetic predictions of future dangerousness. Law and Contemporary Problems, 69, 301–341.
13. Benforado, A. (2010). The geography of criminal law. Cardozo Law Review, 31, 823–904.
14. Blumoff, T. (2010). The neuropsychology of justifications and excuses. Jurimetrics, 50, 391–424.
15. Blumoff, T. (2014). When nature and nurture collide. Durham, NC: Carolina Academic Press.
16. Brosnan, S., Jones, O., Gardner, M., Lambeth, S., & Schapiro, S. (2012). Evolution and the expression of biases: Situational value changes the endowment effect in chimpanzees. Evolution and Human Behavior, 33, 378–386.
17. Brosnan, S., Jones, O., Lambeth, S., Mareno, M., Richardson, A., & Schapiro, S. (2007). Endowment effects in chimpanzees. Current Biology, 17, 1704–1707.
18. Broussard, D. (2012). Principles for passion killing. Emory Law Journal, 62, 179–215.
19. Brown, D. (1991). Human universals. New York, NY: McGraw-Hill.
20. Browne, K. (1995). Sex and temperament in modern society. Arizona Law Review, 37, 971–1106.
21. Browne, K. (2008). The evolutionary psychology of sexual harassment. In T. Shackleford & J. Duntley (Eds.), Evolutionary forensic psychology (pp. 81–100). New York, NY: Oxford University Press.
22. Browne, K. (2013). The selective concern over statistical sex disparities. Florida International University Law Review, 8, 271–285.
23. Buck v. Bell, 274 U.S. 200 (1927).
24. Buckholtz, J., Asplund, C., Dux, P., Zald, D., Gore, J., Jones, O., & Marois, R. (2008). The neural correlates of third-party punishment. Neuron, 60, 930–940.
25. Buss, D. (1999a). Evolutionary psychology: The new science of the mind. Needham Heights, MA: Allyn & Bacon.
26. Buss, D. (1999b). The evolution of desire: Strategies of human mating. New York, NY: Basic Books.
27. Buss, D. (2000). The dangerous passion: Why jealousy is as necessary as love and sex. New York, NY: Free Press.
28. Buss, D. (2005). The murderer next door: Why the mind is designed to kill. New York, NY: Penguin Press.
29. Buss, D. (2012). The evolutionary psychology of crime. Journal of Theoretical and Philosophical Criminology, 1, 90–98.
30. Buss, D., & Shackelford, T. (1997). Human aggression in evolutionary psychological perspective. Clinical Psychology Review, 17, 605–619.
31. Carbone, J., & Cahn, N. (2009a). Examining the biological bases of family law: Lessons to be learned for the evolutionary analysis of law. In M. Freeman & O. Goodenough (Eds.), Law, mind and brain (pp. 323–344). Surrey, England: Ashgate.
32. Carbone, J., & Cahn, N. (2009b). Behavioral biology, the rational actor model, and the new feminist agenda. In D. Gold (Ed.), Law and economics: Toward social justice (pp. 189–198). Bingley, England: Emerald Group.
33. Chen, J. (2008). Biolaw: Cracking the code. Kansas Law Review, 56, 1029–1044.
34. Coletta, R. (1998). The measuring stick of regulatory takings: A biological and cultural analysis. University of Pennsylvania Journal of Constitutional Law, 1, 20–84.
35. Cotter, T. (2005). Memes and copyright. Tulane Law Review, 80, 331–409.
36. Daly, M., & Wilson, M. (1988). Homicide. New York, NY: Aldine de Gruyter.
37. Daly, M., & Wilson, M. (1995). Discriminative parental solicitude and the relevance of evolutionary models to the analysis of motivational systems. In M. S. Gazzaniga (Ed.), The cognitive neurosciences (pp. 1269–1286). Cambridge, MA: MIT Press.
38. Dawkins, R. (1989). The extended phenotype. New York, NY: Oxford University Press.
39. Deakin, S. (2011). Legal evolution. Review of Law & Economics, 7, 659–683.
40. De Coninck, J. (2010). Reinvigorating comparative law through behavioral economics? A cautiously optimistic view. Review of Law & Economics, 7, 711–736.
41. Dennett, D. (1995). Darwin's dangerous idea: Evolution and the meanings of life. New York, NY: Touchstone Books.
42. DeScioli, P., Gilbert, S., & Kurzban, R. (2012). Indelible victims and persistent punishers in moral cognition. Psychological Inquiry, 23, 143–149.
43. DeScioli, P., & Kurzban, R. (2009). Mysteries of morality. Cognition, 112, 281–299.
44. DeScioli, P., & Kurzban, R. (2013). A solution to the mysteries of morality. Psychological Bulletin, 139, 477–496.
45. Dodson, S. (2008). Darwinist view of the living constitution. Vanderbilt Law Review, 61, 1319–1347.
46. Du Laing, B. (2011). Bio-legal history, dual inheritance theory and naturalistic comparative law: On content and context biases in legal evolution. Review of Law & Economics, 7, 685–709.
47. Du Laing, B., & De Coninck, J. (2011). Introduction: Symposium on evolutionary approaches to (comparative) law. Review of Law & Economics, 7, 653–658.
48. Duntley, J., & Shackelford, T. (2006). Toward an evolutionary forensic psychology. Social Biology, 51, 161–165.
49. Duntley, J., & Shackelford, T. (2008). Darwinian foundations of crime and law. Aggression and Violent Behavior, 13, 373–382.
50. Elliott, E. (2001). The tragi-comedy of the commons: Evolutionary biology, economics and environmental law. Virginia Environmental Law Journal, 20, 17–31.
51. Ellman, I., & Lohr, S. (1998). Dissolving the relationship between divorce laws and divorce rates. International Review of Law and Economics, 18, 341–359.
52. Epstein, R. (2009). Happiness and revealed preferences in evolutionary perspective. Vermont Law Review, 33, 559–583.
53. Fikentscher, W., & McGuire, M. (1994). A four-function theory of biology for law. Rechtstheorie, 25, 291–310.
54. Fisher, H. (1994). Anatomy of love. New York, NY: Norton.
55. Flemming, T., Jones, O., Mayo, L., Stoinski, T., & Brosnan, S. (2012). The endowment effect in orangutans. International Journal of Comparative Psychology, 25, 285–298.
56. Frank, R. (1988). Passions within reason. New York, NY: Norton.
57. Freeman, M., & Goodenough, O. (2009). Law, mind and brain. Surrey, England: Ashgate.
58. Frolik, L. (1996). The biological roots of the undue influence doctrine. University of Pittsburgh Law Review, 57, 841–882.
59. Fruehwald, S. (2009). Reciprocal altruism as the basis for contract. University of Louisville Law Review, 47, 489–530.
60. Geu, T. (2009). A single theory of limited liability companies: An evolutionary analysis. Suffolk University Law Review, 42, 507–551.
61. Gigerenzer, G. (1991). How to make cognitive illusions disappear. European Review of Social Psychology, 2, 83–115.
62. Gigerenzer, G. (1998). Ecological intelligence. In D. Cummins & C. Allen (Eds.), The evolution of mind (pp. 9–29). New York, NY: Oxford University Press.
63. Gigerenzer, G., Todd, P., & The ABC Research Group.(1999). Simple heuristics that make us smart. New York, NY: Oxford University Press.
64. Goldman, B. (2008). Science of settlement: Ideas for negotiator. Philadelphia, PA: American Law Institute/American Bar Association.
65. Goldsmith, T. (1994). Biological roots of human nature. New York, NY: Oxford University Press.
66. Goldsmith, T., & Zimmerman, W. (2000). Biology, evolution, and human nature. New York, NY: Wiley.
67. Goldstein, M. (2002). The biological roots of heat-of-passion crimes and honor killings. Politics and the Life Sciences, 21, 28–37.
68. Gommer, H. (2011a). A biological theory of law: Natural law theory revisited. Seattle, WA: CreateSpace/Amazon.
69. Gommer, H. (2011b). Thou shalt not share? Biological notions in intellectual property law. Berichten Industriële Eigendom, 160–166.
70. Goodenough, O. (2001). Law and the biology of commitment. In R. M. Nesse (Ed.), Evolution and the capacity for commitment (pp. 262–291). New York, NY: Russell Sage Foundation.
71. Goodenough, O. (2011). When “stuff happens” isn't enough: How an evolutionary theory of doctrinal and legal system development can enrich comparative legal studies. Review of Law & Economics, 7, 805–820.
72. Goodenough, O., & Decker, G. (2009). Why do good people steal intellectual property? In M. Freeman & O. Goodenough (Eds.), Law, mind, and brain (pp. 345–372). Burlington, VT: Ashgate.
73. Goodenough, O., & Tucker, M. (2010). Law and cognitive neuroscience. Annual Review of Law and Social Science, 6, 61–92.
74. Grady, M., & McGuire, M. (1997). A theory of the origin of natural law. Journal of Contemporary Legal Issues, 8, 87–129.
75. Gruter, M. (1977). Law in sociobiological perspective. Florida State University Law Review, 5, 181–218.
76. Gruter, M. (1979). The origins of legal behavior. Journal of Social and Biological Structures, 2, 43–51.
77. Gruter, M., & Bohannan, P. (1983). Law, biology and culture: The evolution of law. Santa Barbara, CA: Ross-Erikson.
78. Gruter, M., & Masters, R. (1986). Ostracism as a social and biological phenomenon. Ethology and Sociobiology, 7, 149–158.
79. Gruter, M., & Morhenn, M. (2001). The evolution of law and biology. In S. Peterson & A. Somit (Eds.), Evolutionary approaches in the behavioral sciences: Toward a better understanding of human nature (pp. 119–134). Greenwich, CT: JAI Press.
80. Guttentag, M. (2009). Is there a law instinct? Washington Law Review, 87, 269–328.
81. Haselton, M., & Buss, D. (2000). Error management theory: A new perspective on biases in cross-sex mind reading. Journal of Personality and Social Psychology, 78, 81–91.
82. Haselton, M., & Buss, D. (2003). Biases in social judgment: Design flaws or design features? In J. Forgas, K. Williams, & B. von Hippel (Eds.), Social judgments: Implicit and explicit processes (pp. 23–43). Cambridge, England: Cambridge University Press.
83. Hausfater, G., & Hrdy, S. (1984). Infanticide: Comparative and evolutionary perspectives. New York, NY: Aldine.
84. Herring, D. (2006). Foster care safety and the kinship cue of attitude similarity. Minnesota Journal of Law, Science & Technology, 7, 355–392.
85. Herring, D. (2007). The multiethnic placement act: Threat to foster child safety and wellbeing? Michigan Journal of Law Reform, 41, 89–120.
86. Herring, D. (2008). Kinship foster care: Implications of behavioral biology research. Buffalo Law Review, 56, 495–556.
87. Herring, D. (2012). Evolutionary theory and behavioral biology research: Implications for law. In S. Roberts (Ed.), Applied evolutionary psychology (pp. 239–255). New York, NY: Oxford University Press.
88. Herring, D. (2014). Evolutionary perspectives on child welfare law. In T. Shackelford and R. Hansen (Eds.), The evolution of violence (pp. 53–72). New York, NY: Springer Science.
89. Herring, D., Shook, J., Goodkind, S., & Kim, K. (2009). Evolutionary theory and kinship foster care: an initial test of two hypotheses. Capital University Law Review, 38, 291–318.
90. Hill, C., & O'Hara, E. (2006). A cognitive theory of trust. Washington University Law Review, 84, 1717–1796.
91. Hoffman, E., & Spitzer, M. (1993). Willingness to pay vs. willingness to accept. Washington University Law Quarterly, 71, 59–114.
92. Hoffman, M. (2011). Ten legal dissonances. Mercer Law Review, 62, 989–1010.
93. Hoffman, M. (2014). The punisher's brain. Cambridge, England: Cambridge University Press.
94. Hoffman, M., & Goldsmith, T. (2004). The biological roots of punishment. Ohio State Journal of Criminal Law, 1, 627–641.
95. Horton, T. (2011). The coming extinction of Homo economicus and the eclipse of the Chicago school of antitrust. Loyola University Chicago Law Journal, 42, 469–522.
96. Horton, T. (2012). Unraveling the Chicago/Harvard antitrust double helix. University of Baltimore Law Review, 41, 615–670.
97. Horton, T. (2013). Fairness and antitrust reconsidered: An evolutionary perspective. McGeorge Law Review, 44, 823–864.
98. Jones, O. (1997). Evolutionary analysis in law: An introduction and application to child abuse. North Carolina Law Review, 75, 1117–1242.
99. Jones, O. (1999a). Law, behavioral economics, and evolution. Paper presented at Olin Conference on Evolution and Legal Theory, Georgetown University Law Center, April 16, 1999.
100. Jones, O. (1999b). Law, emotions, and behavioral biology. Jurimetrics Journal, 39, 283–289.
101. Jones, O. (1999c). Sex, culture, and the biology of rape. California Law Review, 87, 827–942.
102. Jones, O. (2000). On the nature of norms. Michigan Law Review, 98, 2072–2103.
103. Jones, O. (2001a). Evolutionary analysis in law: Some objections considered. Brooklyn Law Review, 67, 207–232.
104. Jones, O. (2001b). The evolution of irrationality. Jurimetrics Journal, 41, 289–318.
105. Jones, O. (2001c). Prioprioception, non-law, and biolegal history. Florida Law Review, 53, 831–874.
106. Jones, O. (2001d). Time-shifted rationality and the law of law's leverage: Behavioral economics meets behavioral biology. Northwestern University Law Review, 95, 1141–1206.
107. Jones, O. (2004). Law, evolution, and the brain. Philosophical Transactions: Biological Sciences, 359, 1697–1707.
108. Jones, O. (2006). Behavioral genetics and criminal law, in context. Law and Contemporary Problems, 69, 81–100.
109. Jones, O. (in press). Why behavioral economics isn't better, and how it could be. In J. Teitelbaum & K. Zeiler (Eds.), Research handbook on behavioral law and economics. Northampton, MA: Edward Elgar.
110. Jones, O., & Brosnan, S. (2008). Law, biology, and property: A new theory of the endowment effect. William & Mary Law Review, 49, 1935–1990.
111. Jones, O., & Goldsmith, T. (2005). Law and behavioral biology. Columbia Law Review, 105, 405–502.
112. Jones, O., Marois, R., Farah, M., & Greely, H. (2013). Law and neuroscience. The Journal of Neuroscience, 33, 17624–17630.
113. Jones, O., O'Hara O'Connor, E., & Stake, J. (2011). Economics, behavioral biology, and law. Supreme Court Economic Review, 19, 103–141.
114. Jones, O., Schall, J., & Shen, F. (2014). Law and neuroscience. New York, NY: Aspen Publishers.
115. Judge, D., & Hrdy, S. (1992). Allocation of accumulated resources among close kin: Inheritance in Sacramento, California, 1890–1984. Ethology and Sociobiology, 13, 496–522.
116. Kanazawa, S. (2008). Evolutionary psychology and crime. In A. Walsh & K. M. Beaver (Eds.), Contemporary biosocial criminology: New directions in theory and research (pp. 90–110). New York, NY: Taylor & Francis.
117. Kar, R. B. (2006). The deep structure of law and morality. Texas Law Review, 84, 877–942.
118. Kar, R. (2012a). Outcasting, globalization, and the emergence of international law. Yale Law Journal On-Line, 121, 413–477.
119. Kar, R. (2012b). The two faces of morality: How evolutionary theory can both vindicate and debunk morality (with a special nod to the growing importance of law). In J. Fleming & S. Levinson (Eds.), Evolution and morality: NOMOS (pp. 31–99). New York, NY: NYU Press.
120. Kar, R. (2012c). Western legal prehistory. University of Illinois Law Review, 2012, 1499–1702.
121. Kar, R. (2013). The psychological foundations of human rights. In D. Shelton (Ed.), The Oxford handbook of international human rights law (pp. 104–143). New York, NY: Oxford University Press.
122. Krier, J. (2009). Evolutionary theory and the origins of property rights. Cornell Law Review, 95, 139–159.
123. Krueger, F., Hoffman, M., Walter, H., & Grafman, J. (2013). An fMRI investigation of the effects of belief in free will on third-party punishment. Social Cognitive and Affective Neuroscience, 9, 1143–1149.
124. Kuklin, B. (2006). Peril invites rescue: An evolutionary perspective. Hofstra Law Review, 35, 171–216.
125. Kuklin, B. (2008). The morality of evolutionarily self-interested rescues. Arizona State Law Review, 40, 453–526.
126. Kuklin, B. (2009). The natures of universal moralities. Brooklyn Law Review, 75, 463–496.
127. McCullough, M., Kurzban, R., & Tabak, B. (2013). Cognitive systems for revenge and forgiveness. Behavioral and Brain Science, 36, 1–15.
128. McGinnis, J. (1997). The human constitution and constitutive law. Journal of Contemporary Legal Issues, 8, 211–239.
129. Mikhail, J. (2007). Universal moral grammar. TRENDS in Cognitive Sciences, 11, 143–152.
130. Mikhail, J. (2009). Is the prohibition of homicide universal? Brooklyn Law Review, 75, 497–515.
131. Mikhail, J. (2011). Elements of moral cognition. New York, NY: Cambridge University Press.
132. Monahan, J. (2000). Could “law and evolution” be the next “law and economics”? Virginia Journal of Social Policy and the Law, 8, 123–128.
133. Nesse, N., & Williams, G. (1996). Why we get sick. New York, NY: Vintage Books.
134. O'Hara, E. (2004). How neuroscience might advance the law. Philosophical Transactions of the Royal Society B: Biological Sciences, 359, 1677–1684.
135. O'Hara, E., & Yarn, D. (2002). On apology and consilience. Washington Law Review, 77, 1121–1192.
136. Parekh, N. (2004). When nice guys finish first: the evolution of cooperation, the study of law, and the ordering of legal regimes. University of Michigan Journal of Law Reform, 37, 909–953.
137. Patrick, C. (in press). A new synthesis for law and emotions: Insights from the behavioral sciences. Arizona State Law Journal, 47.
138. Petersen, M. (2013). Adaptationism and intuitions about modern criminal justice. Behavioral and Brain Sciences, 36, 31–32.
139. Petersen, M., Sell, A., Tooby, J., & Cosmides, L. (2010). Evolutionary psychology and criminal justice: A recalibrational theory of punishment and reconciliation. In H. Høgh-Olesen (Ed.), Human morality & sociality: Evolutionary & comparative perspectives (pp. 72–131). London, England: Palgrave Macmillan.
140. Petersen, M., Sell, A., Tooby, J., & Cosmides, L. (2012). To punish or repair? Evolutionary psychology and lay intuitions about modern criminal justice. Evolution and Human Behavior, 33, 682–695.
141. Pinker, S. (2002). The blank slate. New York, NY: Viking Press.
142. Platek, S., Keenan, J., & Shackelford, T. (2006). Evolutionary cognitive neuroscience. Cambridge, MA: MIT Press.
143. Richardson, B. (2011). A damp squib: Environmental law from a human evolutionary perspective. Osgoode CLPE Research Paper Series, 7, 2–42.
144. Richerson, P., & Boyd, R. (2005). Not by genes alone. Chicago, IL: The University of Chicago Press.
145. Ridgway, J. (2011). Patternicity and persuasion. Southern Illinois University Law Journal, 35, 269–308.
146. Robinson, P., Kurzban, R., & Jones, O. (2007). The origins of shared intuitions of justice. Vanderbilt Law Review, 60, 1633–1688.
147. Rodgers, W. (1993). Where environmental law and biology meet. University of Colorado Law Review, 65, 25–75.
148. Ruhl, J. (1996). The fitness of law. Vanderbilt Law Review, 49, 1406–1490.
149. Ruhl, J. (2008). Law's complexity—A primer. Georgia State University Law Review, 24, 885–911.
150. Seaman, J. (2005). Form and (dys)function in sexual harassment law: Biology, culture, and the spandrels of Title VII. Arizona State University Law Review, 37, 321–433.
151. Seaman, J. (2007). The peahen's tale, or dressing our parts at work. Duke Journal of Gender Law & Policy, 14, 423–466.
152. Segal, N., & Marelich, W. (2011). Social closeness and gift giving by twin parents toward nieces and nephews: An update. Personality and Individual Differences, 50, 101–105.
153. Seto, T. (2005). Originalism vs. precedent: An evolutionary perspective. Loyola of Los Angeles Law Review, 38, 2001–2026.
154. Simon, H. (1990). Invariants of human behavior. Annual Review of Psychology, 41, 1–20.
155. Slovic, P., Fischhoff, B. & Lichtenstein, S. (1982). Facts versus fears: Understanding perceived risk. In D. Kahneman, P. Slovic, & A. Tversky (Eds.), Judgment under uncertainty (pp. 463–492). Cambridge, MA: Cambridge University Press.
156. Stake, J. (1990). Darwin, donations, and the illusion of dead hand control. Tulane Law Review, 64, 705–781.
157. Stake, J. (2004). The property “instinct.” Philosophical Transactions of the Royal Society B: Biological Sciences, 359, 1763–1774.
158. Stake, J. (2009). Just (and efficient?) compensation for governmental expropriations, In M. Freeman & O. Goodenough (Eds.), Law, mind, and brain (pp. 299–321). Surrey, England: Ashgate.
159. Stout, L. (2011). Cultivating conscience: How good laws make good people. Princeton, NJ: Princeton University Press.
160. Thomson, J. (2008). Did the victim deserve to die? Darwin goes to court. In J. Duntley & T. Shackelford (Eds.), Evolutionary forensic psychology (pp. 268–287). New York, NY: Oxford University Press.
161. Treadway, M., Buckholtz, J., Martin, J., Jan, K., Asplund, C., Ginther, M., Jones, O., & Marois, R. (2014). Corticolimbic gating of emotion-driven punishment. Nature Neuroscience, 17, 1270–1275.
162. Tversky, A., & Kahneman, D. (1982). Judgment under uncertainty, In D. Kahneman, P. Slovic, & A. Tversky (Eds.), Judgment under uncertainty (pp. 3–20). Cambridge, MA: Cambridge University Press.
163. Ulen, T. (1994). Rational choice and the economic analysis of law. Law and Social Inquiry, 19, 487–522.
164. Ulen, T. (2001). Evolution, human behavior, and law. Florida Law Review, 53, 931–946.
165. Urias, A. (2004). The politics of biology: Evolutionary biology and the exclusion of women from combat. Southern California Review of Law and Women's Studies, 14, 83–135.
166. Vaughn, L. (2011). Feeling at home: Law, cognitive science, and narrative. McGeorge Law Review, 43, 999–1030.
167. Walsh, A. (2006). Evolutionary psychology and criminal behavior. In J. H. Barkow (Ed.), Missing the revolution: Darwinism for social scientists (pp. 234–277). New York, NY: Oxford University Press.
168. Wangenheim, G. (2010). Evolutionary theories in law and economics and their use for comparative legal theory. Review of Law & Economics, 7, 737–765.
169. Wax, A. (2004). Evolution and the bounds of human nature. Law and Philosophy, 23, 527–591.
170. Wilson, M. (1987). Impact of the uncertainty of paternity on family law. University of Toronto Faculty of Law Review, 45, 216–242.
171. Wilson, M. (2005). An evolutionary perspective on male domestic violence. American Journal of Criminal Law, 32, 291–323.
172. Yarn, D., & Jones, G. (2009). A biological approach to understanding resistance to apology, forgiveness, and reconciliation in group conflict. Law and Contemporary Problems, 72, 63–81.
173. Yelpaala, K. (2008). Legal consciousness and contractual obligations. McGeorge Law Review, 39, 193–266.
174. Zeki, S., & Goodenough, O. (2006). Law and the brain. New York, NY: Oxford University Press.