Foundations of the Eart: Global Ecological Change and the Book of Job

What is the animal whose bonds have been loosed in these verses? When one initially reads these, one immediately thinks of wild donkeys in the hills that have somehow eluded domestication—more or less an equine parallel to the oxen in the field and the aurochs in the wild, which were discussed in the last chapter. However, donkeys are derived from an African animal, the African wild ass (Equus africanus),1 which is native to Ethiopia, Eritrea, and Somalia.² While there are prehistoric records of E. africanus from Arabia and elsewhere in the Fertile Crescent,³ these are not the animals being described in the Book of Job. The Joban wild ass is an animal called the onager (Equus hemionus).⁴ Its preferences for dry grasslands (mountain steppe, steppe, semidesert, and desert plains)⁵ are well characterized by the habitats described in Job 39:6 (“the steppe for its home, the salt land for its dwelling place…”). Onagers also have a direct etymological connection to the Job text. The word onager actually means “wild ass,” derived from the ancient Greek ὄναγρος, from ὄνος (ass) combined with ἄγριος (wild).

Onagers somewhat resemble donkeys, but they are larger.⁶ They are horselike in many of their features. Indeed, the hemionus species name in its scientific name is from the Latin (hemi or half, onus or ass), meaning “half ass.” This refers to the animal’s appearance, which is halfway between that of donkeys and horses. They are not hybrids between donkeys and horses. A donkey-horse hybrid is called a mule, with a horse as its mother. A hinny (or jennet) is born from a donkey mother. Onagers are a separate species. Their color varies seasonally: reddish-brown in summer, yellowish-brown in winter months. A black stripe with a white border extends down the middle of the back. The tail of the onager has short hairs at its base and long hair on the lower section of the tail, a distinctive difference from the flowing tails of horses. Onagers are between horses and donkeys in height and weight, somewhat closer to the size of a donkey. Their ears are intermediate between the large donkey’s ears and the smaller horse’s ears.

Who tamed the onager? Was it domesticated? These questions are a matter of some debate at this time. A 1930s excavation of the Sumerian site at Tell Asmar (third millennium BCE)7 in Iraq uncovered large numbers of onager bones.⁸ This led to the speculation that the bones were from domesticated animals being raised for their meat.⁹ From Çatal Hüyük, a pair of wall paintings each of a man holding a tamed onager dates to the sixth millennium BCE.¹⁰ There are also a range of other onager-related objects: clay tablets from the city of Susa in the Elam civilization in southwestern Iran (dated between 3250–3000 BCE), with four onagers in a row with a group of people; a later clay tablet from Elam (3000–2800 BCE) decorated with several onager heads; a painting from Tell Halaf in Syria showing onager-drawn chariots, from 3000–2800 BCE.¹¹ These have been taken as indications of an early taming and potentially an early domestication of onagers.¹²

One particularly striking onager-related artifact is the Standard of Ur, an inlayed hollow wooden box with a background of lapis lazuli, with shell and red limestone inlayed details, dating from 2500 BCE. The box ends are trapezoidal, and the sides are twenty by forty-eight centimeters. One of the side panels shows a battle scene. This “war” panel illustrates the Sumerian spearmen, other infantry, and four-wheeled chariots trampling the enemy. The other side’s panel shows a peaceful scene, perhaps after the subsequent victory. In all, seven pairs of equids appear on the standard.¹³ It was found by Sir Leonard Woolley in the royal cemetery of the Babylonian city of Ur, which was located south of what is now Baghdad.¹⁴ Woolley was of the opinion that the object was a battle standard carried on a pole (hence the name); others speculate that it might be part of the sound box of some sort of musical instrument. It now resides in the British Museum.

The Standard of Ur has been the focus of debates on whether the onager was actually domesticated or not. Was the onager used as a draft animal? Among the pairs of equids on the panels, there are some animals, which clearly display the distinctive onager tails, drawing chariots. Then why haven’t onagers been found with the wear marks of bits on their teeth, as is the case with ancient horses? The onagers on the standard seem to be harnessed with a strap around the jaws and another behind the ear, but without bridles.¹⁵ This method of control also was used with horses, and the nostrils of horses were sometimes slit to keep the nose straps from hampering their airflow.¹⁶ When unharnessed, the onagers illustrated on the standard have rings in their noses.¹⁷

In the middle of the fourth millennium BCE, a horse-oriented people in what is called the Botai culture from northern Kazakhstan in the Eurasian steppe possibly had domesticated horses. There is a pattern of wear on a few of the animals’ teeth that imply the use of a bit, an indicator that these were ridden animals. This is not definitive for a domesticated horse as either domesticated or tamed animals could have been ridden. Additional evidence for domestication includes measurements of Botai horse leg bones (metacarpals), which demonstrate they resembled Bronze Age domestic horses and not Paleolithic wild horses from the same region.¹⁹ Also, the pottery from the sites contains chemical evidence of products derived from mare’s milk. Taken as a whole, these are strong indications of the presence of domesticated horses in the Botai culture.²⁰ Artistic evidence of domesticated horses only dates from the end of the third millennium BCE, so this pushes back the evidence in dated texts and illustrations.

The key to the domestication of the horse may have been a genetic change predisposing some horses to breed in captivity. The domesticated horse seems to have derived from many mothers but from only one father. Genetically, the Y-chromosomes found in a wide collection of male horses indicate that the horse was derived from a single stallion or a limited number of related stallions.21 The mitochondrial DNA of horses indicates a large number of matriarchal lines.²² The implication is that a chance genetic change produced a stallion that was tolerant of the conditions involved with breeding in captivity. This gave humans an ability to control horse breeding and is consistent with the low number of horse “founding fathers.” During the continuing process of domestication, tamed or wild mares from different regions were crossed to sires from this line of stallions.²³ Thus the modern horse has many founding mares. This pattern of propagation might have allowed the rapid expansion of horse populations throughout Europe around 2000 BCE.²⁴

If the onager was domesticated, as the Standard of Ur and other artifacts indicate, then “Who has loosed the bonds” of the domesticated onager? This puzzle may be revealed in translations of the ancient writings of the Sumerians. In 1840, the royal library of the Assyrian King Ashurnanipal (688–627 BCE), consisting of twenty thousand clay tablets written in cuneiform script, were found at Nineveh, on the eastern bank of the Tigris River opposite modern Mosul, Iraq. This great library and other cuneiform writings have been the focus of translators ever since.²⁵ It has been found that there are several words used for different equids, including terms for donkeys, onagers, horses, and hybrids between onagers and donkeys.²⁶ One tablet from 2050 BCE provides a three-year account, which records the ownership of thirty-seven horses, 360 onagers, 727 onager-donkey hybrids, and 2,204 donkeys.²⁷ From the texts, these hybrid onager-donkeys (using male onagers as sires) were large, powerful animals. They were nearly horse sized and were yoked in teams to draw chariots.

In mules and other equid hybrids, the appearance of the heads and tails of the offspring generally reflect the male.28 By this logic, the onagers on the Standard of Ur could have been these onager-donkey hybrids, which would have had smaller ears than the donkeys but also onager-like tails. To maintain these valuable hybrids, tamed onagers from the wild would be regularly captured as foals, tamed, and maintained to breed with donkeys. When the horse became available as a domesticated species, tamed male onagers as breeders to donkeys were no longer needed. From around 2000 BCE in Sumerian writings, the horse is mentioned increasingly more frequently, and the mention of onagers disappears: “Presumably once the horse, which could not only breed hybrids but was also in itself a better animal and trainable, had appeared on the scene, there was no longer any call for keeping the onagers to do nothing but eat, drink, and enjoy the pleasures of their harems.”²⁹

The hybridization of onagers and donkeys appears to be an intensive practice of the ancient Sumer empire in the western arm of the Fertile Crescent in the Tigris and Euphrates rivers’ lower drainage region. The practice of the hybridization of onagers and donkeys was occasionally reported in the eighteenth and nineteenth centuries CE,³⁰ but large-scale hybrid production using onagers ceased millennia earlier with the advent of the domesticated horse. So, in answer to this chapter’s whirlwind question, the onager was freed by humans. It was “set loose,” or, more accurately, it no longer continued to be tamed for reasons of economics—it was easier and more effective to use horses and mules as draft animals to produce agricultural products.³¹

The opening actors in this narrative, the wild horses, wild donkeys, and onagers, have not fared well in the passage of history. The wild species and source of the domestic horse, the wild horse (E. ferus), is now represented by the 325 free-ranging, reintroduced, and native-born Przewalski’s horses (Equus ferus przewalskii) in Mongolia. This horse subspecies, which is not likely to be the horse subspecies that produced the domesticated horse (E. callabus), became extinct in the wild in 1969. All living Przewalski’s horses descended from thirteen or fourteen individuals assembled from zoos and propagated in a captive breeding program starting in 1992.³² A second subspecies of the wild horse, the tarpan (E. ferus ferus, also known as the Eurasian wild horse), became extinct relatively recently.³³ The last tarpan died in captivity in Russia in 1909.³⁴ The African wild ass, the progenitor of the domestic donkey, is a critically endangered species.³⁵ The onager is an endangered species that is much restricted in its former range and is decreasing in numbers.

The sad situation of these remarkable wild equids, which were the source stock that contributed so greatly to the development of human civilization, is part of a current pattern of species endangerment and extinction. This loss of biotic diversity springs from a range of human pressures including change in the land cover of the Earth.

The domestication and release of animals along with the transportation of plant and animal species has changed the terrestrial landscapes of the world. The development of agriculture and the power of draft animals to perform the heavy work of pulling plows and moving large stones, trees, and eventually wheeled carts gave humans the capacity to alter their surrounding ecosystems greatly. Modern technology has amplified this trend. From prehistoric times into modern times, humans have progressed from being keystone species at the local to the regional to the continental to the planetary level.

What is a keystone species? Basically, such a species controls the structure and function of the ecosystems in which they occur. The name refers to the keystone in an arch. Remove the keystone, and the arch tumbles under stress; remove the keystone species, and the ecosystem collapses with change.

The original keystone-species concept was produced from a study on the role of a starfish (Pisaster ochraceus) on the rocky intertidal zone in the U.S. Pacific Northwest coast.36 The rocky intertidal is found on rocks along a seashore in the band between high and low tides. The rocks there are covered with various barnacles and mussels, which are the prey of the predatory starfish. When the starfish were experimentally removed from areas of the rocky intertidal, white acorn barnacles (Balanus glandula) initially increased to take over 60 to 80 percent of the space. Nine months later, these barnacles were crowded out by small, rapidly growing California mussels (Mytilus californianus) and goose-neck barnacles (Mitella polymerus) along with some rock barnacles (Semibalanus cariosus). Eventually in areas with the starfish removed, mussels became dominant across the area, with occasional patches of goose-neck barnacles.³⁷ The predator starfish was deemed a keystone species because its presence strongly controlled the ecosystem on the intertidal rock surfaces. Its presence increased the overall diversity of species in this case, and its removal decreased species richness. Other cases demonstrate the opposite diversity pattern.

In other ecosystems, herbivores serve as keystone species. African elephants (Loxodonta africana) can be remarkably destructive animals with regard to the forest and shrub cover in savanna ecosystems.³⁸ Variation in elephant densities significantly affects the mixture of grass and woody plants in savanna vegetation and thus the fuel loads for wildfires.³⁹ Changes in wildfires and in woody cover both can alter the nature of the savanna ecosystem.

Plants can also function as keystone species. In the central wheat belt of Western Australia, an assemblage of nonmigratory birds called honeyeaters (in the family Meliphagidae) feed on flower nectar and simultaneously pollinate an array of shrubs and small trees in the Proteaceae family. Honeyeaters are attractive, mostly small birds colored in combinations of yellow, black, green, and red; the proteaceous shrubs display flowers, mostly in the red, orange, and yellow spectra that typify a bird-pollenated species. The different flowers are sized and shaped to accommodate honeyeaters of appropriate sizes and with particular bill lengths. The plants flower at different times, a phenomenon associated with timing reproductions so as not to compete with other flowers for the services of an appropriately sized honeyeater. However, there is a short time of year when only one shrub species, the orange banksia (Banksia prionotes), blooms and sustains all of the honeyeaters. Eliminate the keystone orange banksia, and the honeyeaters, as well as all of the plants they pollinate, could well disappear from the region.

In the last chapter, Neolithic people, Polynesians, specifically the Mangaiains, functioned as keystone species capable of dramatic modifications of the islands of the Pacific. Hunting/gathering people using fire as a landscape-management tool also place humanity in the keystone species role. The capability of technological human society to modify landscapes, regions, and the planet is easily demonstrable. More subtle is the effect of the mere presence of low densities of hunting/gathering people on the ecosystems they inhabit.

One can easily imagine positive feedback systems in which the seeds of fruits that are discarded after being carried by their dispersers (or that pass through the digestive tracts of their dispersers unharmed) would evolve to forms that are increasingly preferable by their disperser. The coadaptations between animal dispersers and plants have evolved a remarkable array of adaptations.40 One would expect this to be no less the case for human dispersal systems as well.

In a process referred to as domiculture,⁴¹ species adapt to human “homes.” They evolve mechanisms to promote their dispersal to human camp sites, latrines, and waste dumps. They develop life histories that increase the likelihood of their survival once there. Domiculture was initially used to describe the observable effects of Australian aboriginal people living in hunting-and-gathering societies on the Cape York Peninsula on the surrounding flora.⁴² Basically, the transport of the best edible fruits back to temporary base camps selects for larger, tastier fruits on plants near these camp sites.

The domiculture of a species provides a potential starting point for eventual domestication of some plants. Dating the age of archaeological sites requires samples of formerly living material. Frequently and depending on the location, these often are the cherry pits, pawpaw seeds, olive pits, and melon or other seeds that have been dropped, spit out, or excreted by the inhabitants of the sites. Fruits and vegetables with large fleshy edible parts that encourage the dispersal of hard, digestion-resistant seeds fill the produce sections of modern and traditional markets. Many of these may have begun their path to becoming domesticated cultivars through domiculture in response to humans as a keystone species.

The earliest weeds to have been dated are from 3200 BCE. These are the seeds of the cockle (Lolium temulentum), found mixed with cereal grains from two archaeological sites located near the Dead Sea.43 Cockle grows in the same zones as wheat. It so resembles wheat that it has the alternate common name of false wheat. It mimics wheat through most of its life cycle. Only when the plant develops seeds does its wheat mimicry break down. Its seed head is lighter than that of wheat, and it stands erect in mature wheat fields; wheat heads droop from their weight.

There were likely weeds well before the cockle’s seeds from 3200 BCE. Weeds are also likely to exist for some time to come. Fields prepared for planting food crops represent a high-value location for other species of plants as well. Such sites are selected as locations where plants will grow vigorously—combinations of deeper soils with more nutrient elements, well watered, good drainage, and easily tilled. Weeds are sometimes characterized as plants in the wrong place. From the weed’s perspective, agricultural land is clearly the right place. The agricultural sites represent desirable prime locations for what have been call “ruderal species” of plants.44 Ruderals have good dispersal abilities, grow rapidly under favorable conditions, and are relatively short lived. In more natural ecosystems, the ruderal life history allows plants to colonize and pioneer the initial sites created following a disturbance. In agricultural systems, these same attributes produce a predilection to colonize agricultural fields.

Weeds may not be edible at all; they may even poisonous. Because they compete with crops, they lower the yield from the harvest. Thus, agronomists have been locked in battle with weeds since agriculture was invented. In this battle, weeds have evolved two tactics, both under the heading of mimicry. The first tactic is created by natural selection, which produces plants that resemble the crop plants. This makes it difficult for humans to separate the weed plants from the crop plants. In the second tactic, weed seeds mimic the crop seeds. This allows the weed seeds to “hide” among the crop seeds and be planted in the next crop cycle.

Evolution in seed mimicry in weeds counters human mechanical strategies to clean the weed seeds out of the next season’s crop seeds. Sift the seeds for size, and the selection favors weed seeds the same size as the crop; sort the seeds for color, and selection for seed colors produces matching colors in the weed seeds; winnow the seeds to sort for density, and the weed seeds match the densities of the crop. These evolutionary changes can develop quickly and can modify the plants considerably. There are some weeds, the aforementioned cockle and the field bineweed (Convolvolus arvense), for example, which now are found only in fields.

Other weeds have evolved other complex strategies for self-perpetuation in agricultural fields. An initial adjustment in weeds often tunes the time of the maturation of the weed seeds to match the crop harvest interval. The wild oat (Avena sterilis) has a germination pattern such that only about half of a given year’s production of seeds germinates in the following year. The rest remain dormant to produce for future germinations in later years.45 Some weeds in wheat fields (wild rye, Secale cereal; and hooded canary grass, Phalaris paradoxa) have seed spikes that shed their lower part, which sprinkles seeds onto the soil. The seeds of the upper part of the seed spike remain. These seeds are threshed with the wheat and then show up next the year among the planted wheat seeds.⁴⁶ Herbicides are a chemical counteroffensive in the struggle between humans and weeds, but herbicide-resistant weeds are appearing in several areas.⁴⁷

Agricultural fields full of edible, high-energy plants and granaries loaded with seeds represent a strong incentive for animal species to alter their behavior or for natural selection to favor adaptations that allow access to these resources. Legions of species of birds, mammals, and insects and other arthropods were either preadapted or have rapidly adapted to take advantage of the stores of materials in human-dominated landscapes. Other creatures have taken advantage of the shelter and the moderation of the environmental extremes provided by human constructions. The “built environment” has its own menagerie, often of less than pleasant animals.⁴⁸ The agricultural landscape is no less full of noxious creatures. As is the case with weeds, some animals have undergone significant behavioral change or, in other cases, considerable evolutionary change.

A single pest animal removal service in Atlanta, Georgia, listed their services as removal of bats, beavers, carpenter bees, coyotes, dead animals, feral cats, flying squirrel, foxes, gray squirrels, groundhogs, honeybees, hornets, mice, moles, opossums, pigeons, raccoons, rats, skunks, snakes, squirrels, yellow jackets, wasps, and woodpeckers. This diverse assemblage of pests is not unique to Atlanta; this firm could be franchised in major cities all over the world. The length of this list is surprising, but the ecological roles of these animals also command one’s attention. Some of the creatures, such as the house mouse (Mus musculus) and Norway rat (Rattus norvegicus), have cohabitated with humans for millennia and have evolved to fit the human environment. Originating in Asia,49 they are essentially found everywhere there are people, with the exception of Antarctica, the Arctic latitudes, and a few remote islands. Their close proximity to humans has led to domesticated varieties, many of which are widely used as laboratory animals. Other widespread creatures are formerly domesticated animals reverted to a wild state: pigeons (Columbia livia) and feral cats (Felis catus). Still others on the list are essentially local wild animals: they open garbage bags in search of food, eat food left out for pets (or eat the pets themselves), munch on garden plants, chew up parts of houses, dig up the lawn, find nest sites to shelter their young, and generally adapt to a human-dominated world. This adaptation to humans is an ongoing process underway across the Earth.

The control of pest animals, particularly the insects that destroy crops, has prompted a chemical war of long duration. Indeed, chemical warfare research for World War I and II catalyzed a new stage in this ongoing war against pests.⁵⁰

Pesticides and insecticides have been in use for a long time. Pliny the Elder suggested, “a remedy against ants, which are by no means the slightest plague in a garden that is not kept well watered, to stop up the mouths of their holes with sea-slime or ashes.”⁵¹ Among a lengthy collection of similar stratagems, he also recommended the use of salt and ashes to prevent worms in figs and beaten larkspur to kill vermin.⁵² Prior to 1800, pyrethrum made from the ground flowers of chrysanthemum was used as an “insect powder.” Pyrethrum was harvested by hand and thus was too expensive to use broadly in agriculture.⁵³ Paris green, an arsenic powder, was used as an insecticide in the 1860s and 1870s in the United States, and lead arsenate was used at the turn of the twentieth century to control a great range of insects.⁵⁴ World War I brought a marriage between science and the military. In the United States, the Chemical Warfare Service stimulated research on war gases as insecticides.⁵⁵

In 1874, O. Zeidler synthesized the chemical, dichlorodiphenyl trichloroethane, DDT.56 DDT was discovered to be an effective insecticide in 1939 by P. H. Müller, who received the 1948 Nobel Prize in Physiology and Medicine for his efforts. DDT came into widespread use in World War II as a weapon against the mosquitoes that transport malaria. After the war, the insecticide was applied in large-scale agriculture against pest insects. In 1962, Rachel Carson published her book Silent Spring, which informed the public of the widespread presence of DDT in wildlife.⁵⁷

Silent Spring communicated the potential risk of DDT and other similar insecticides called chlorinated hydrocarbons to the public. Within a few years, birds such as the peregrine falcon, brown pelican, and bald eagle were found to be laying thin-shelled eggs, an apparent consequence of the concentration of DDT up through the food webs that supported them. Decreases in these species were being observed and reported by birdwatchers by the later 1960s.⁵⁸ There was an obvious connection to human public health, in that the human agricultural food chain was also delivering DDT in food to people. DDT was banned in Germany and the United States in 1973 and by the United Kingdom in 1984. It was outlawed by the Stockholm Convention in 2004.

The Nobel Prize in Medicine for Müller in 1948 stemmed from DDT’s efficacy against malaria. Fifty-six years later, its ban derived from its potential hazard as a widely dispersed chemical. A “principle of intended consequences,”⁵⁹ which dictates that positive changes can produce other, sometimes negative responses in interactive ecological-environmental systems, creates difficult planetary decisions. If there is a moral to the DDT story, it would be that it is hard to do but one thing when modifying the environment. This moral also pertains to other cases involving introduced exotic species, the alteration of important environmental variables, changing land cover, and the other planetary issues raised by the Joban whirlwind questions.

As organisms adjust to human-created ecological systems, the possibility of new diseases crossing over from wild disease reservoirs is increasingly likely. Diseases can be classified by the agent (infectious viruses, bacteria, fungi, and parasites) and the number of hosts in the infectious cycle.60 Two-factor complexes consist of agents transmitted directly from person to person (one agent, one host), such as polio-virus. Three-factor complexes involve transmission through a vector or invertebrate intermediate host, such as a snail, mosquito, or tick or other arthropod. Dengue and malaria, for instance, are transmitted from person to mosquito to person. Four-factor complexes involve transmission between a nonhuman vertebrate and an arthropod, with humans usually being accidental hosts. Eastern and western encephalitis viruses, for example, are maintained in a reservoir of mosquitoes and birds, with transmission to humans as a spillover.

When people change ecological conditions, they may create breeding sites for disease vectors and vertebrate hosts. For example, malaria has become epidemic in the western Amazon region of Brazil, where the population has grown tenfold since 1970. The immigrants are involved in gold mining and forestry and have settled in areas undergoing rapid deforestation.61 Anopheles darlingi mosquitoes breed in the standing water of open-cast mining sites and forest clearings. Initially, people from malaria-endemic regions of Brazil arrived already infected to seed the area. As a second example, the triatomine bugs (“kissing bugs”), which can transmit Chagas’ disease, live in the mud walls of homes in Brazil and Argentina.⁶² A change in construction methods could eliminate the bug’s hiding places. Spraying homes with insecticides with residual activity in some cases also has controlled the insect.

Viruses, parasites, fungi, and bacteria have evolved from their ancestral forms along with the ancestral forms of their animal reservoirs. As new species have evolved, so have new versions of the microbes that inhabit them. The high diversity of plants and animals in the tropics is accompanied by high species diversity of their associated microorganisms. Greater host diversity implies greater diversity of disease agents.

Human incursions into undeveloped regions serve to increase the exposure of humans to new, so-called emerging diseases. Some of these are simultaneously terrible and lethal, such as the viral disease Ebola hemorrhagic fever. In 1976, Flemish nuns in a missionary hospital in the Ebola River Valley in the Republic of the Congo first discovered this disease. It has had periodic and deadly outbreaks in the region since that time. Fruit bats may be a host for the disease.⁶³ Focality is a term that describes the degree of localization of a disease. The relatively sudden appearance of a deadly human disease that clearly seems to have a reservoir in some rainforest animals, such as Ebola, represents a disease with high focality. Particularly in the tropics, the often local distribution of the reservoir species creates localized diseases with high focality. This implies that there are potentially numerous and as yet undescribed disease agents that are infecting wild vertebrates and vectors in tropical forests and have the potential to cause disease in people.

Hopefully, our remarkable progress in medical science will insulate us from emerging diseases, at least to some degree. The whirlwind question, “Who has set the wild ass free?” foreshadows the modern era: humans are setting all manner of things free, often in new locations. Next, let us consider the consequences of these releases.

Humans have been keystone species for millennia and are consolidating their role at larger and larger spatial scales. As the planetary keystone species, humans currently are engaged in an ad hoc program of Earth’s alteration. Because the planet is so strongly modified by human action, the term “Anthropocene” has been proposed to describe our current state, as if it were a new geological epoch.64 Several aspects of the changes that humans have wrought are expressed on the chemistry of the planet and particularly the chemistry of the atmosphere. These changes are the topics of chapters that follow. Earth, in the Anthropocene epoch, is undergoing profound ecological rearrangement as well. Human-altered ecosystems change under the influence of the human keystone species and in the human release of plants and animals to new parts of the planet. One pronounced biological effect of the Anthropocene has been the dispersal of introduced species across the planet, with an associated spreading of feral versions of our domesticated animal portfolio.

An old-fashioned term from the formative era of ecology is chorology, the science of the geographic spread of organisms and the study of the rules of distribution of living organisms across the Earth’s surface.⁶⁵ Chorology has revealed changes in the positions of continents over geological time and the geographic origins of different plants and animals. The riddle of the underlying causes of species distribution has promoted speculation and theory building in ecology for the past two hundred years. One early chorological theory was produced by the great Swedish biologist Carl von Linné (“Linnaeus”), the same person who invented and developed an important system of describing species. The modern basis for naming and relating species today derives from the Linnaean classification system.

The classification of species using a genus/species binomial name was developed by Linnaeus. The first edition of his book, Systema Naturae, was a short pamphlet produced in the Netherlands, where he served as a medical doctor, in 1735.66 It continued to be issued in new and large editions throughout his life. His use of the parts of flowers as a basis to classify plants caused rancorous debate. Johann Georg Siegesbeck criticized and eventually ridiculed him for being too focused on sexual matters (flowers and flower parts) in his classification.⁶⁷ The ensuing smear campaign originating from Siegesbeck left the issue sufficiently touchy that the Pope forbade Linnaeus’s works from the Vatican.⁶⁸

Linnaeus’s important tenth edition,⁶⁹ which included a classification with scientific (binomial) names of animals, was produced in two volumes in 1758 and 1759. He had listed binomial names of plants in his earlier book, Species Plantarum (1753).⁷⁰ His classification of humans, which grouped them with the apes, also touched off a firestorm.⁷¹ The issue was religious: if man was created in God’s image, it was blasphemy to associate their appearance with that of simians.⁷² Darwin’s Origin of the Species prompted the same response a century later. For all of this religious tumult, Linnaeus himself was a strongly religious person. He was drawn to natural theology, a popular philosophy in the eighteenth century. Its premise posited that since God created the world, one can understand God’s wisdom through studying the natural world, God’s creation. Considering the Book of Job’s whirlwind questions would be an obvious pursuit in natural theology.

Chorologically, Linnaeus thought that unchanging species had spread across the Earth from the landing point of the biblical Noah’s ark (Genesis 8:4) in the mountains of the ancient proto-Armenian kingdom of Ararat (860 BCE–590 BCE). Ararat was also known as Urartu.⁷³ The inhabitants of Noah’s ark would have dispersed from there to generate the floras and faunas of the regions of the world. Now, if this were true, he reasoned, species experiencing similar environmental conditions but in different locations would have originated from Noah’s landing point and should be the same. Further, the diversity of species of a given sort should be lower the farther one moved from the Ararat dispersal point.

Linnaeus’s Ararat-centered chorology wilted in the face of scientific exploration, which simply showed this not to be the case. By 1762, Comte Georges Louis Leclerc de Buffon observed that the large, ecologically similar mammals of the tropical parts of the Old and New Worlds are quite different taxonomically.74 Alexander von Humboldt expanded Buffon’s observation that unrelated species are found in separated but environmentally similar locations (sometimes called Buffon’s Law) to flowering plants, birds, reptiles, insects, and spiders.⁷⁵

Modern chorologists might have had a more difficult time in discerning the geographical patterns of flowering plants than Buffon or Humboldt. Locations with a long history of trade and transport with other regions have large numbers of alien species that have been transported from elsewhere: 36 percent of the vascular plant species in New York State are introduced alien species, 28 percent in Ontario, 11 percent in Poland, 16 percent in Finland, 33 percent in Norway.⁷⁶ Islands both nearby and remote have even higher numbers: the British Isles have 43 percent alien plant species, the Canary Islands 35 percent, Bermuda 65 percent, New Zealand 40 percent, the Galapagos 30 percent, Hawaii 44 percent.⁷⁷ Today, disproving Linnaeus’s Ararat theory of plant and animal distributions by reading the current patterns of species would be made more complex by the “haze” of alien species in unexpected locations all over the world.

The planetary increase of introduced plants and animals and particularly the establishment of novel feral animals immediately come to mind when one hears the Joban whirlwind question, “Who has set the wild ass free?” The wild horse and the wild donkey are teetering near the brink of extinction, but the feral versions of their domesticated cousins are prospering. When domesticates escape or are released into the wild, they often are occupying human-altered landscapes. These “semiwild” landscapes, created by the human keystone species, share attributes with the agrarian landscapes in which the formerly domesticated species were husbanded.

Domesticated animals have been selected for several different traits, one of which is elevated reproductive rates. Often domesticated animals have more frequent reproductive intervals than do their wild primogenitors. Creatures that breed once a year in the wild breed might twice a year when domesticated. Species in which the presence of an alpha female suppresses reproduction in subordinate females may lose this trait when domesticated. Species with multiple births may have larger litters. Artificial selection in domestication emphasizes fertility. The high reproductive capacity allows feral domesticated animals to explode into human-altered habitats and to take rapid advantage of novel situations.

The introduction of the rabbit to the Australian continent is an excellent example of the conjunction of both of these factors: habitat change and human transport leading to the successful invasion of much of a continent by an alien feral animal.78 Domesticated European rabbits (Oryctolagus cuniculus) and European people arrived on the same boats, the First Fleet to Botany Bay, to become Australian residents in January 1788.⁷⁹ Subsequently, the rabbit was shipped to several other ports in Australia. It was introduced to the island of Tasmania (in 1820), where it eventually became established as a feral animal.⁸⁰

On Christmas night, 1859, the rabbit’s explosive invasion of the Australian mainland started in Melbourne, with the arrival of twenty-four rabbits unloaded off of the Black Ball clipper ship Lightning, sailing out of Liverpool.81 These would have been feral domesticated rabbits: neither was the rabbit native to the British Isles.⁸² The rabbits, along with sixty-six partridges and four hares, had been shipped to Thomas Austin by his brother, James, who was still in England. Thomas may have immediately released some of his rabbits onto his estate. By 1862, Thomas Austin’s rabbits, held in a fenced enclosure on his estate, Barwon Park, near the town of Winchelsea, Victoria, numbered in the thousands. The rabbits became so numerous that they soon were chewing the bark off of the trees, and eventually they either escaped or were released.⁸³ They were damaging neighboring farms by the early 1860s. By the mid-1860s, rabbit hunts and rabbit coursing were popular field sports among the wealthy in several locales where rabbits at been loosed on the land.

Without native rabbit diseases, the rabbit moved rapidly into a climate and habitat that matched its requirements very well. In the decade of the 1860s rabbits spread like a wave over Australia, advancing as much as one hundred kilometers per year—the most rapid spread known for any colonizing mammal anywhere on Earth.⁸⁴ The 1860s was a dry decade in Australia. Pastures were degraded. Sheep populations crashed to as much as half their former density. The rabbit population exploded into the very sort of degraded landscape for which it had been bred by its human domesticators. The combination of a small fluctuation in climatic conditions and a human-altered landscape set the conditions for the rabbit to take over Australia.

The rabbit’s invasion of Australia is a story that repeats in other places at other times. At the dawn of history, the European rabbit was restricted to the Iberian Peninsula (present-day Spain and Portugal). The species was also found in a small region in northern Africa, but it may have been transported there by the Phoenicians. The animals have been spread across the world, often intentionally, by people. Pliny the Elder reported outbreaks of rabbits that had been introduced to the Balearic Islands off of the Mediterranean coast of Spain: “There is also a species of hare, in Spain, which is called the rabbit; it is extremely prolific, and produces famine in the Balearic islands, by destroying the harvests.…It is a well-known fact, that the inhabitants of the Balearic Islands begged of the late Emperor Augustus the aid of a number of soldiers, to prevent the too rapid increase of these animals.”⁸⁵

Through time, sailors have transported rabbits and have released them onto islands to provide future provisioning while en route on subsequent voyages. This practice started with the early Phoenicians (1500–300 BCE). Roman sailors brought rabbits to the Balearic Islands around 30 BCE and to Corsica by 230 CE. Subsequent sailors have spread rabbits to over eight hundred islands worldwide.86

This monument commemorates the centenary of the first liberation of Red Deer in Ontago in March 1871. The deer were presented to the Ontago Acclimatisation Society by the 11th Earl of Dahlhousie of Brechen in Scotland and shipped to Port Chalmers on the City of Dunedin and The Warrior Queen. Seven deer were liberated in this area after being shipped to Oamaru in the paddle steamer Wallace and transported over Lindis Pass by bullock wagon. These deer formed the basis of the world renowned Otango South Westland red deer herd. Erected by the New Zealand Deerstalkers Association Inc. North Ontago Branch, 1971.

The effort to capture red deer (Cervis elaphus) in Scotland, ship them halfway around the world on two boats (the City of Dunedin and the Warrior Queen), then load them onto a paddle steamer and then into ox carts to haul them to the outskirts of Ontago for release seems like a remarkable amount of work and expense. One would expect such an endeavor to be attempted (and succeed) but once. That would be incorrect. Starting in 1861, red deer, mostly from Scotland, were introduced at different locations in New Zealand more than 220 times!⁸⁷

Included among the brace of mammals (thirty-three species), birds (forty-four species), and other species introduced to New Zealand from elsewhere were a remarkable number of species of deer from all over the world.88 Hunting may have been the sport of nobles in England, but it was the pastime of the commoner in New Zealand.⁸⁹ This egalitarian spirit may have compelled the eventual introduction of the red deer as well as sika deer (Cervis nippon), Javan rusa deer (C. timorensis), sambar deer (C. unicolor), wapiti or Rocky Mountain elk (C. elaphus nelsoni), fallow deer (Dama dama), white-tailed deer (Odocoileus virginianus), chamois (Rupicapra rupicapra), and the Himalayan thar (Hemitragus jemlahicus). The diversity of deer in New Zealand appears to be affecting the ground vegetation from their grazing, but the long-term effects are far from clear.⁹⁰

Many of the species released in New Zealand and elsewhere were the product of “acclimatization societies,” founded in several nations, many of them European colonies. Inspired by the writing of the French naturalist Saint-Hilaire,⁹¹ acclimatization societies spread worldwide after being first founded as the Societe Zoologique d’Acclimatation in Paris. Their objective was to establish species for pleasure and food in locations around the world. Some of the rationales of these releases seem surreal from a modern viewpoint. For example, the line from Shakespeare’s 1597 Henry IV, “Nay, I’ll have a starling shall be taught to speak nothing but ‘Mortimer,’” inspired the American Acclimatization Society in New York, who were intent on introducing all the species mentioned in Shakespeare’s works to the New World, to release European starlings (Sturnus vulgaris) in Central Park in New York City.⁹² Starlings have subsequently become a pest animal. Some of the acclimatization societies’ other projects included the introduction of house sparrows (Passer domesticus) around the world, the already mentioned importation of various game animals to Australia (rabbits) and New Zealand (deer), Australian possums to New Zealand, and European carp and trout to river drainages worldwide.⁹³

Should the release of red deer and a menagerie of other creatures to New Zealand seem the product of eccentric mores from other era in a faraway place, today “game ranches” in the American West are being stocked with a brace of exotic game animals for fee-paying trophy hunters. One ranch in Texas selected at random as an example has fifteen species of exotic large mammal species from elsewhere in North America, Europe, Asia, and Africa. There is a branch facility of the same operation in England that offers eight species of deer for the hunter. These are commercial ventures that house valuable animals. The cost to shoot the largest of the African antelopes, the eland (Taurotragus oryx), is, at the time of this writing, $4,750. The owners of these animals are unlikely to want them to wander off of their property. Nevertheless, escape is always possible. These established populations of introduced animals are not radically different from the efforts of the acclimatization societies of over a century ago.

The magnitude of this biological expatriation is staggering, but darker implications hide in the details.⁹⁶ In North America, it is thought that at least twenty thousand exotic microorganisms have established themselves from other continents. How might an inspector of agricultural products know that one of these was Cryphonectria parasitica, or chestnut blight, a plant disease that eliminated the American chestnut (Castanea dentata) as a canopy species from the eastern North American forest, where it once was a dominant species? European rabbits had been present as an escaped domesticated animal since the first colonists arrived in 1788. How one could expect that a small shipment of rabbits from England seventy-one years later would touch off the European rabbit invasion of Australia? Who would have guessed that the mongoose (Herpestes javanicus) brought to Fiji to control rats would turn out to be a voracious predator of birds, small mammals, reptiles, and sea turtle eggs—especially after all its good press in Kipling’s Rikki-Tikki-Tavi? The potential risk in the large wave of invasive species challenges research scientists to provide practical solutions, a difficult task, to say the least. The basic issues boil down to a few questions: Which species or groups of species are most likely to invade? How rapidly can they invade? What makes an ecosystem vulnerable to invasion? How can we control or eliminate invasive species?⁹⁷ These are not easy questions to answer.

Even worse were the earlier Spanish accounts of outbreaks of smallpox. Smallpox was imported from Spain to Hispaniola in the Caribbean in 1507. It exterminated entire tribes, but then the disease died out. The African slave trade reintroduced the disease to the Caribbean as well as to Mexico and Brazil.99 An outbreak in Hispaniola originating with African slaves working in the mines wiped out about one-third of the native inhabitants. The outbreak spread to Cuba in 1518 and then to Puerto Rico in 1519. It killed over half of the people on both of these islands.¹⁰⁰ Narváez landed on the Mexican coast near modern Vera Cruz in 1520 with an African slave with smallpox on board. The result was described by a Spanish friar in 1525:

At the time that Captain Pánfilo de Narváez landed in this country, there was in one of his ships a negro stricken with smallpox, a disease which had never been seen here. At this time New Spain was extremely full of people, and when the smallpox began to attack the Indians it became so great a pestilence among them throughout the land that in most provinces more than half the population died; in others the proportion was little less. For as the Indians did not know the remedy for the disease and were very much in the habit of bathing frequently, whether well or ill, and continued to do so even when suffering from smallpox, they died in heaps, like bedbugs.¹⁰¹

The lethality of Old World diseases such as smallpox was also seen in other diseases that had crossed the Atlantic Ocean with European explorers, whose ancestors had been in long contact with domesticated animals and crossed-over diseases. These would include measles (a viral disease originating from the cattle disease rinderpest) and influenza (a diversity of virus strains from humans and several domesticated animals including fowl and swine).¹⁰²

The novel-contact disease remains a problem for relatively isolated people who have had minimal contact with the outside world. Hopefully, modern medicine will insulate most of us from the plagues of the past, but this is clearly not a time to relax our collective vigilance in the field of disease control. The spread of plant and animal diseases is another matter. The diversity of potentially infectious plant and animal diseases, as well as the spread of a growing assortment of insect pests, presents a major problem that has only been magnified by the increased globalization of trade.103 The volumes of things that are moved intercontinentally to feed, clothe, and equip the world’s societies are simultaneously providing potential vectors for all sorts of organisms.¹⁰⁴

Ecologists study relatively pristine ecosystems to understand the consequences of many complicated ecological processes that interact to produce observable patterns. Mature, relatively undisturbed ecological systems provide an essential baseline to understand how small environmental changes might alter these natural systems. In a procedural sense, astronomers and ecologists approach their objects of study in a similar manner. Ecosystems and solar systems are not easy experimental objects. The modus operandi is to observe the systems, compare them, and understand them in terms of underlying processes that cause what is observed.

Comparison of large-scale patterns of diversity across different continents yields a regular relationship between the size of a continent and its species diversity. Larger continents have more species. What if the increased continental exchanges of species made the Earth’s land diversity function as if it was a large interconnected continent? If the current relationship between continent size and diversity holds, there should be a sizable reduction in biodiversity on a connected Earth. For mammals, this land area–to-species relationship implies that a thoroughly connected world might have about half as many mammal species as are now found on the separated land areas of our planet.¹⁰⁵

We live in an era in which truly undisturbed, mature ecosystems are becoming rare.106 The studies of natural systems that are not greatly modified by humans provide necessary insight on ecosystem function. Early ecological research focused on such systems, and they are no less valuable now. However, an additional understanding of human-modified ecosystems and their functioning commands study because the planet continues to be altered by human action. We know from the fossil and geological record that past ecosystems with different mixtures of species and different environmental conditions coalesce, persist, and then eventually change over time. The instances in the geological past in which floras and faunas mingled after the formation of land bridges often featured the extinction of many species. For example, with the formation of the isthmus of Panama around three million years ago, the remarkably diverse marsupial mammal fauna of South America collapsed and was replaced by more advanced placental mammals from North America. Thus, we have reason to believe that the species we have loosed across the Earth will also change the planet.

The question remains: “What will these new ecosystems be like?” One would like to be optimistic. Along a roadside, introduced trees and shrubs colonize wasteland, substituting greenery for bare earth. We are drawn to gardens and arboreta loaded with exotic plants from all over the world, and we take pleasure in this human-created biological diversity. In New York City, peregrine falcons swoop down to catch pigeons from the canyons between skyscrapers and feed their young in nests on the high building ledges. Pigeons are a domesticated cliff-dwelling rock dove. The peregrines are rebuilding their populations, which had been decimated by DDT use. The entire scene is an urban version of falcons hunting their prey on the face of a Scottish cliff—a scenario featuring a truly wild event that most people would never hope to see.

While there are positives, at least from some points of view in all of this, there are also significant negatives. Many of these stem from feedback loops between the exotics and the ecosystems they inhabit. Fire-tolerant alien plants prosper under fires and create additional fuel for more frequent or hotter fires. Introduced fish eliminate natural fisheries that support coastal towns. Inedible or even poisonous weeds invade pastures and prosper when the native grasses are overgrazed by cattle or native animals. Eucalyptus trees introduced in the subtropics to supply fuel wood for cooking or heating plunge their roots into the ground water and reduce the already scant water supply. Housecats functioning as predators and subsidized by their owners reduce bird populations in suburban areas. The tiger mosquito (Aedes albopictus), an extremely invasive species worldwide and imported to the United States in cargo from southern Asia, can vector several diseases, including West Nile virus, yellow fever, St. Louis encephalitis, dengue fever, and Chikungunya fever.107 Once one realizes that some of these alien species are a problem, it can be virtually impossible to remove them—it is hard to get the genie back in the bottle.

The onager as depicted in Job is an analogue to the unicorn translation of the re’em in the King James translation of Job 39:9 discussed in the previous chapter. The onager (the wild ass or swift ass) and the re’em (when translated as unicorn, as in the King James Bible) represented a creature of untamable wildness that would remain so despite human efforts. The onager was an unusual case in that the “domesticated” form was a hybrid. When it was replaced by the horse, the hybrid was no longer created through a process of onager taming and interbreeding with donkeys. The domesticated hybrid disappeared and only the wild form remained. It was “set free” in a rather special sense. Unfortunately, many other creatures that we have domesticated, tamed, or captured do not have such internally programmed self-destruct buttons when set free. Instead, many of them have come to fill niches in other locations and, in particular, in places influenced by the human keystone species. The global implications of this topic will be taken up again in chapter 8.