Humans are animals with unique abilities, particularly in the realms of language, imagination, and culture. However, like our physical bodies, our mental abilities contain echoes of our related mammalian cousins. Like our decision-making systems, our tremendous abilities have precursors in other animal behaviors.
I am fascinated by history and love to travel and see the old ruins of great civilizations. I have stood on the walls of Troy and looked out over the plains of Hisarlik where Achilles and Odysseus once stood. I have stood on the stage of the ancient Greek city of Miletus and sat in the stands of the Roman stadium of Ephesus. I am always fascinated by how much remains constant. The defensive fortifications of a medieval castle in Japan (such as Himeji Castle) are similar to those of a medieval European fortress (such as Harlech Castle, in Wales). The components of an ancient Roman stadium are instantly recognizable to anyone who has attended a modern sports stadium, the rows of benches (numbered and labeled by row), even the concession stands. Similarly, we can appreciate narratives from the world over. The modern reader recognizes Achilles’ petulance at Agamemnon’s demands in Homer’s Iliad and Odysseus’ war-driven exhaustion in the Odyssey. The trickster Anansi continues to capture children’s imaginations,1 and the adventures of d’Artagnan and the Three Musketeers2 still spark the interest of young boys and girls everywhere. Whether it be the graffiti on the wall of the boys’ dormitory in Priene (a ruined city in Turkey) or the shape of the council seats in Wupatki (in northern Arizona), we recognize familiar human interactions in our ancient ancestors. Something is constant through the ages, something that makes it possible for us to look at a set of drawings on the cave walls of Lascaux and know that some person painted them.
Certainly, there is a qualitative difference between humans and the other animals that have been mentioned in this book. Beavers may create dams of wood that modify their local environment, but they have never put a man (a beaver?) on the moon. Outside of literature, no rats have ever built cities or written novels.3 But as we have seen throughout this book, our decision-making system, much like our physical bodies, contain echoes of our related mammalian cousins. If we evolved from animals, then how are we different from them? Even the phrase “evolved from animals” implies a trajectory from animals to humans, with humans placed above and beyond. A better statement would be that we are part of the evolutionary history, a moment in evolutionary time. We are not evolved from animals—we too are animals.
There is much about humans that seems unique among animals. No other animal has language skills like ours. (Although it has been possible to teach some animals the rudiments of language, none of them has ever achieved language skills beyond that of a young child.4) The complexity of the cities we build and our individual specializations within those cities are unparalleled. (Although termites and other social insects also build large hives, these hives are made of a limited number of specific individual castes and do not resemble the flexible complexity of human cities.5) And we seem to be destroying our ecosystem at an unprecedented speed.6 However, as is nicely pointed out by Matt Ridley in The Agile Gene, lots of species are unique. Termites build in mud, squids squirt ink, and cobras spit venom. Simply being unique is not enough. The question is What makes us unique?
Jane Goodall, who has studied a tribe of chimpanzees in Gombe for the past 50 years, complained that every time she found her chimpanzees showing signs of what makes us human, the philosophers would move the goalposts.7 At first, humans were tool users. But as early as the 1920s, the psychologist Wolfgang Köhler found that apes could learn to stack boxes purposefully to find reward.8 In the field, Jane Goodall observed chimpanzees using twigs to pull ants and termites from tree stumps.9
Then humans were the only ones to make tools. But then Goodall observed that the chimpanzees were actually making their tools, finding the right stick, cleaning it off, and preparing it.10 (It is now known that otters and crows and many other species also use tools. Otters will use rocks to break open sea urchins, and crows have been found to make tools out of twigs and leaves to fish for insects.11)
Then it was suggested that humans are the only ones to have developed separate cultures. But chimpanzee tribes use different tools to attain food. In the Tai Forest in the Ivory Coast, a chimpanzee tribe uses rocks to crack kola nuts (which have a very hard shell). Chimpanzees from the Gombe tribe do not know how to use rocks to crack kola nuts, and chimpanzees from the Tai Forest tribe do not know how to fish for termites.12 These different abilities are spread from chimpanzee to chimpanzee culturally.
Cultural abilities have even been observed as they were discovered. In the 1960s, Japanese macaque monkeys began to wash sweet potatoes in the ocean to remove dirt and to add salt.13 The ability spread first from the discoverer (a young female) to others she knew, and then to the others in the tribe. It followed trails of kin, parenting, and training. Subsequent observations of cultural behaviors have found that they generally spread through celebrity and dominance such that higher-rank primates (who are closely observed by lower-rank ones) spread the meme faster than lower-rank primates.14
So other animals show tool use, and other primates have the presence of culture (or at least a precursor to culture). What makes humans different?
One suggestion has been that humans are the only ones to think about other places and other times, to (as it were) “mentally time-travel.”15 But, as we’ve seen, rats show search behaviors when making choices and seem to represent expectations of the outcomes of their actions.16 Nikki Clayton at Cambridge has seen that scrub jays recognize when and where they cached food, can take into account how long that food will remain edible, and can take into account the likelihood that another jay is aware of the hiding location of the food cache.17 Both monkeys and rats can represent alternative options that might have been when they make errors (as in “I could have got reward if I had made the other choice”).18
That being said, it is not clear that scrub jays can maintain episodic memory beyond food caches,19 that monkeys or rats can imagine far-distant futures or pasts, or that chimpanzee culture extends to the kind of narrative stories that we tell ourselves. I suspect that the difference is going to be one of quantitative differences becoming a qualitative one. Nevertheless, the things that make us human have their roots in our evolutionary history.20
Careful observations have shown that other animals play, laugh, fight, even mount what, for lack of any other terminology, can only be called wars.21 And yet, there are differences. We have a flexibility in our decision-making systems that is far beyond what other animals can do. We communicate with language that is infinitely flexible and capable of depth of meaning. We can work together in groups larger and more complex than other species. In particular, our groups come and go. We are capable of shifting groups with context more easily than other species.22 As Aristotle defined us, we are the “political” animal.23
Our social identity can be remarkably dynamic and flexible. We have extended families, tribes, and nations, but also groups based on the places where we work, our churches, mosques, and temples, and our sports teams and political parties.A People who work together as part of the same group in one context (at a job or cheering for a sports team) can dissolve into anger and intractable argument in another context (such as politics).
Some philosophers attribute the difference to language,25 which has several important properties that may explain our differences. First, language can communicate very detailed information (such as plans or instructions) quickly.26 Second, it can store knowledge outside of an individual (as in books or webpages).27 Third, language provides an interactive social network and marks our place within it.28
We often use language as actions in themselves.29 A person saying “I do” at his or her wedding is committing to a specific contractual deal. As pointed out by Orson Scott Card in his novel Speaker for the Dead, a marriage is a contract between three parties—the two people being married and the community that agrees to treat them as married.30
Language can also be used to build on itself—one person can provide part of the answer, and another can build on it.31 This is the misnamed “wisdom” of the group, which is not so much wisdom (groups can be very unwise) but rather a positive feedback process of knowledge.32 One of the major breakthroughs that led to the scientific revolution and our modern world was the development of the scientific journal in the 1600s.B A scientific article reports a single result or finding, and, although it is generally a complete story, it does not have to completely answer all the questions that might arise. Before the journals, science was reported in books and monographs, which required decades to write. This meant that other scientists could not follow up on one’s work until it was complete. By providing a means of reporting a partial answer, scientific journals allowed scientists to point other scientists in the right direction, to put a single brick in the edifice of science rather than having to construct an entire building by oneself.
The other thing that language can do is point. Language allows us to coordinate our goals and to coordinate our attention.33 It can point a direction, identify a danger, a target, or an outcome. The level to which other animals can track referents is still being debated, but they do not seem to track them as easily as humans do. For example, humans are the only ape with white sclera, which enables others to know where we are looking.34 Much of our social interaction is based on knowing where the other person is looking. Take, for example, the importance of eye contact in conversation.35 (Of course, knowing where someone is looking is not always a good thing, as any intercepted NFL quarterback knows.)
Fundamentally, however, one of the largest differences between humans and other animals is in what has traditionally been called morality.36 Jane Goodall observed sociopathy in her chimpanzees—a mother and daughter (named Passion and Pom) developed a cannibalistic procedure attacking new mothers and their infants where one of them would distract a new mother and the other would attack and kill the infant.37 If one of the large males was in the area, he would defend the new mother and infant, but the males did not attack Passion and Pom outside of the context of their crime. Humans do not tolerate such sociopaths.38
Whether the difference is a qualitative leap (a change in kind that can be clearly separated) or merely the repeated effect of small quantitative changes (changes in level or depth) is still unknown. Yet, something is different. Termites may build mounds, and other animals may build nests of incredible complexity, but those mounds are not cities on the scale of New York or Tokyo or Alexandria. Chimpanzees may fight wars, but those wars do not include machine guns, tanks, or nuclear bombs.C Bower birds may create art, but that art is not disseminated to and discussed by millions of bower birds all over the world. Baboons may live in groups, but those groups do not “friend” each other on Facebook.
There have been fascinating discussions of just how intelligent some species are. Elephants have highly complex societies, calculate expectations for the availability of fruit and water as a function of recent weather patterns, and remember their dead for years.39 Vervet monkeys lie about attacking predators to escape bullies.40 And whales and dolphins sing amazingly complex songs that depend on their cultural and societal interactions.41 Although something may be different about humans, the things that fundamentally make us human, our language, our minds, and our decision-making systems, like our physical bodies, share commonalities with and derive from our animal nature.
In the next two chapters, we will explore two of those uniquenesses: morality and consciousness.
• Jane Goodall and Hugo van Lawick (1971/1988/2000). In the Shadow of Man. Boston: Houghton Mifflin.
• Jane Goodall (1990). Through a Window. Boston: Houghton Mifflin.
• Frans de Waal (1982/2000). Chimpanzee Politics: Power and Sex among Apes. Baltimore, MD: Johns Hopkins Press.
• Frans de Waal (2001). The Ape and the Sushi Master: Cultural Reflections of a Primatologist. New York: Basic Books.
• Robert M. Sapolsky (2001). A Primate’s Memoir. New York: Touchstone.
• Michael Tomassello (2005). Constructing a Language: A Usage-Based Theory of Language Acquisition. Cambridge, MA: Harvard.