Chapter One PLEISTOCENE EXTINCTIONS * * * Beginning 11,000 years ago, at the end of the period known as the Pleistocene, many animal species that had flourished just a short time before vanished from North America. Men and women had been in the New World for only a relatively short time, and scholars have hotly debated the coincidence of their arrival and the extinctions. Paul Martin, a palynologist and geochronologist, spurred the debate more than any other person. When he proclaimed in the late 1960s that "man, and man alone, was responsible" for the extinctions, he set off a firestorm that shows little sign of abating. Branding the ancient Indians--so-called Paleoindians--as superpredators, Martin likened their assault on Pleistocene animals to a blitzkrieg , evoking the aggressive, assaulting imagery of the Nazi war machine. Martin could not have made a more apt word choice for grabbing the public imagination. Over the last three decades "American Blitzkrieg" and "Slaughter of Mastodons Caused Their Extinction" have defined headlines, and writers in popular magazines like National Geographic concluded confidently that scientists suspect "man the hunter" as the "villain" in Pleistocene extinctions. There is no room for the Ecological Indian here. As Martin himself wrote in 1967, "that business of the noble savage, a child of nature, living in an unspoiled Garden of Eden until the `discovery' of the New World by Europeans is apparently untrue, since the destruction of fauna, if not of habitat, was far greater before Columbus than at any time since." For Martin, that realization is "provocative," "deeply disturbing," and "even revolutionary." To no surprise, Martin's findings fed the conservative press who argued that because of the (supposed) sins of their earliest ancestors, Native North Americans today lack authority to occupy the moral high ground on environmental issues. Martin's ideas have found support and reached a wide audience for over thirty years, but how well do they stand up today? For well over a century, the consensus in the scientific community has been that Paleoindians, the ancestors of today's American Indians, wandered eastward into North America from northeastern Asia. But among American Indians outside the scientific community, that idea has not met with universal acceptance. Some have taken issue with the idea that their ancestors came initially from Asia. Asked about the origin of the world and human beings, or about the migrations of their ancestors, Indians have sometimes responded that their communities were never anywhere other than where they were at the moment the question was posed. Their ancestors, they said, came into the present world from worlds preceding and beneath the current one, through mouths of caves or from holes in the ground. Other native people believed they had migrated from the east, west, or elsewhere. Some living in the interior of the continent thought that their ancestors once lived far away on the shores of salty seas. In days before they had incorporated European ideas of their origins into their own, American Indians answered questions about their origin and historical movements in as many different voices as there were nations with separate cultures. Even today native people do not speak with one voice on these or any other issues. Some adhere to contemporary versions of their traditional beliefs. But not all do. Many instead have long since converted to the position favored by archaeologists, paleontologists, and other scientists, that Indians came to the New World from Asia thousands of years ago. Like all scientific explanations, this one is changing based on the steady accumulation of data. Each year new sites or dates offer fresh insight on how and when people came into and spread throughout North and South America. The nature of science is to debate theories and to test and confirm or falsify hypotheses spawned by theories. As with evolution, a long period of shared understanding may be suddenly punctuated by "fresh" insight fitting more seamlessly both new data and the broader historical context in which all scientific thought exists, and a new consensus begins to build. One recent example of this process is illustrated by debates concerning mass extinctions before the Pleistocene, for which there is growing widespread agreement that asteroids--a radical theory when initially proposed--and climate change spelled the end of major orders of living things. The scientific community's consensus is that when Paleoindians wandered eastward from northeastern Asia to North America, they came across a broad and vast land known as Beringia . At the heart of Beringia is a continental shelf that was exposed during lower sea levels of the Pleistocene and is today covered by the Bering and Chukchi seas. In short order, Paleoindians migrated south from Beringia along the west coast or through a corridor between two massive continental ice sheets and spread rapidly to the southern tip of South America. There was ample time and opportunity during the Pleistocene for Paleoindians to wander from Asia to America through Beringia. The Pleistocene era lasted for two million years, and was marked by periods when temperatures were cool and glaciers advanced and by periods when temperatures were warm and glaciers retreated. During the warmer eras marked by glacial retreats, the sea level was essentially today's, and Asia and North America were separated by a strait as they are today. But during the cooler periods when glaciers advanced, the sea level was lower, continental ice sheets were more expansive, and Beringia was exposed. A drop in the sea of 150 feet below today's level was all that was required to remove the obstacle of a strait and expose Beringia as a landmass. At these times, Asia and North America were joined, even if continental glaciers imposed to the east and south. The general scheme is not in dispute; the details, not surprisingly, are debated. For example, many discuss precisely when climatic and environmental conditions permitted Paleoindians to cross Beringia--how much earlier than the era of Paleoindian sites that have been securely dated (see below). Even though evidence for human occupation of Siberia during very early times is mounting, there is no evidence that human beings moved across Beringia prior to a cool era beginning some 80,000 years ago. Indeed from 115,000 to 80,000 years ago, the sea level was essentially today's and water blocked movement by land. But from 80,000 to 10,000 years ago there were long periods when temperatures were very cool and the sea level dropped more than 150 feet below its present level, removing the barrier of a strait; at other moments, temperatures were not as cold and a narrow strait remained as an impediment--not, however, if people possessed the technology to cross water or ice. There were two especially welcoming eras during this 70,000-year-long span. The first was from 65,000 to 23,000 years ago, when the strait--if there was one--was even narrower than today and continental ice sheets loomed but evidently were not joined to block passage toward the heart of the continent to the south (for those who headed in that direction). The second was from 23,000 to 10,000 years ago when the sea level was even lower, and a straitless Beringia grew into a broad plain measuring 1,000 miles from north to south. How inadequate the metaphor of bridge for the landmass that formed between Asia and North America! As a one-thousand-mile-wide plain, the "Bering land bridge," as it has been called, was surely attractive to generations of animals large and small, as well as to people following them. At different places and separate times, Beringia was probably a cold but productive steppe rich in fauna and a colder more barren tundra marked by much lower biological productivity. From 80,000 to 10,000 years ago, its vegetation changed from being adapted to wetter and milder conditions to being more suitable for colder and drier climate and longer ice cover. At the end of the Pleistocene, wetter and warmer conditions caused a rapid buildup of peat and an explosion in the numbers of birch trees in Beringia. At its greatest extent, this landmass was no doubt marked by different vegetation zones from north to south, and in the late Pleistocene by a mosaic of environments and species. For human predators, the most important characteristic may have been the abundant graze afforded by grassy vegetation for mammoths, bisons, and horses. For most of the time when Beringia was at its greatest expanse from 23,000 to 10,000 years ago, beyond it to the south and east coastal glaciers loomed and two massive ice sheets covered much of Canada. When they were at their maximum extent 18,000 years ago, the ice sheets encased Canada and the Great Lakes. But as temperatures warmed, they retreated, and waters released from them and from shrinking polar ice caps raised sea levels. After several thousand years, Beringia flooded, Bering Strait re-formed, and human migration between the Old and New World took place henceforth only across water or on ice. For the story of migration into the heart of North America, however, these changes mattered little. Men and women were already in the New World, and the major problem they faced was how to move south. One route was along the coast; some archaeologists argue that this route was the major and the earliest one. Another was through an inland gap or corridor from interior Alaska through the Yukon Territory, British Columbia, and Alberta--along the eastern flanks of the Rocky Mountains. The corridor formed some 13,000 to 11,000 years ago as the continental ice sheets pulled back from each other, allowing men and women, when conditions were optimal, to migrate into the heart of North America. Both routes marked the way into environments like today's but for their location farther south. Bordering the ice sheet was a narrow zone of periglacial tundra, south of which was boreal forest and mixed coniferous and deciduous forests in the East and plains in the West, and desert farther south. Each of these major environments contained grazers, browsers, and predators that would soon be extinct. The extinctions were remarkable by any measure. Animals familiar and unfamiliar, widespread and local, and large and small disappeared. Some were well-known creatures like lemmings, salamanders, and various birds. But many were not, and they constituted a fabulous bestiary. The mammals, especially the ones that were unfamiliar and large, have attracted great attention. How many mammalian species disappeared will probably always be unknown because of uncertainty over species boundaries, but at least thirty-five mammalian genera vanished. Mammals weighing more than one hundred pounds that became extinct have drawn intense interest partly because of their assumed attractiveness to human hunters. For one familiar only with today's North American fauna, these so-called megafauna (literally, large animals) were exceptional. They included exotic hulking tusked mammoths and mastodons that roamed prairies and boggy woodlands, respectively, towering elephant-like over almost all else. Several types of slow-moving, giant ground sloths ranging in size from several hundred pounds to twenty feet long in the same weight range as the mammoths also vanished. So did rhinocerous-sized pampatheres, a kind of giant armadillo, and armored two-thousand-pound, six-foot-long glyptodonts resembling nothing known today. Many herbivores disappeared, including single-hump camels, stocky six-foot-long capybaras, five-hundred-pound tapirs, three-hundred-pound giant beavers, four-horned antelopes, horses, bison-sized shrub oxen, and stag-moose with fantastic multiple-palmated and tined antlers. Carnivores also died out, including dire wolves whose large heads and powerful jaws made them resemble hyenas and huge fearsome fifteen-hundred-pound short-faced bears that were slim and possibly very quick and agile. Two large serrated-toothed cats vanished: scimitar-toothed cats that fed on mammoth young, and great saber-toothed cats that could gape, shark-like, opening their jaws to a one-hundred-degree angle before stabbing or ripping open prey with their enormous canines. All vanished. The end for many came between 11,000 and 10,000 years ago, a watershed millennium that opened with the disappearance of many members of the amazing bestiary and closed with the demise of the remaining camels, horses, mammoths, mastodons, and other megafauna. These species entered oblivion in a geological blink. The big question is why, which returns us to Martin's proclamation, "Man, and man alone, was responsible." Can we accept this? In his search for proof, Martin marshaled the power of simulation to his side. On the basis of assumptions about when Paleoindians arrived south of the continental ice sheets, population growth and movement, and kill rates, he and his co-workers simulated the rapid human movement and killings--the "blitzkrieg." In one scenario, one hundred Paleoindians arrived on the Alberta prairies some 12,000 years ago. Each year, they moved southward just twenty miles and killed only one dozen animals per person. They also reproduced, doubling their population every twenty years. Except for the reproduction rate, the assumptions underlying these figures seem fairly modest. Yet based on them, Paleoindians in only three hundred years numbered 100,000, spread two thousand miles south, and killed over ninety million one-thousand-pound animals. Using more conservative assumptions in other simulations, Martin and others argued that it still took relatively few years to reach first the Gulf of Mexico and then Tierra del Fuego at the tip of South America, and to hunt megafauna to their doom. The thesis has proved seductive--and resilient. Granted, the overwhelming image one gets from Martin's blitzkrieg is of restless Paleoindians constantly on the move. Hunting people, they were always on the go along a "front" (as in a military campaign). They expanded methodically, killing a mammoth here, a mastodon there, a glyptodont one day, a dim-witted giant ground sloth or cumbersome giant beaver the next. Martin argued that men (and women) arrived in the New World with knowledge of hunting large animals, but these same animals lacked experience with human predators and thus did not fear them, and so hunters left megafaunal extinctions in their wake. They ate little but megafaunal meat and wasted up to half of what they killed. Singularly focused on big game, they ignored fish, shellfish, plants, and other less dramatic sources of food. They moved fast, killed efficiently, and were fecund. Critics, scoffing at overly generous assumptions about kill rates, population growth, and population movement that depart from cautious, reasonable inferences from twentieth-century hunting-gathering peoples, complain that Paleoindians were too successful. Martin speculated that Paleoindians were successful in part because they were newly arrived in the New World, and animals lacked fear of them as predators and did not develop an awareness of how fatal their encounters with them would be until it was too late. When Martin first proposed his thesis some thirty years ago, archaeologists generally accepted that humans were in the New World 10,000 to 11,000 years ago but not much earlier. Today, as a result of a flurry of activity on early sites, it appears likely that Indians reached southern South America some 12,500 years ago, and a new consensus is emerging over an arrival date in the New World of 13,000 to 14,000 years ago. An arrival time of any earlier is sharply disputed. The lines are clearly drawn between most archaeologists, who are uncomfortable with dates earlier than roughly 14,000 years ago, and a vocal, persistent minority asserting that Paleoindians reached the New World 30,000 or 40,000 years ago. While linguistic, dental, and genetic theories lend support to the older dates, it is currently doubtful that a precise chronology can be derived from these theories. In the meantime, the earliest dated sites are plagued by various methodological problems. This debate will not be solved to everyone's satisfaction anytime soon, but at this stage it seems prudent to remain skeptical of dates earlier than 14,000 years ago. Animals like slow-moving, sluggish ground sloths must have been especially vulnerable to human predation, but animals with far more presumed agility than gigantic sloths disappeared too. Martin's argument that the superpredators killed them all easily and quickly because they lacked time to develop fear is weakened both by the likelihood that Paleoindians arrived 1,000 to 3,000 years before the watershed millennium when most megafaunal animals vanished and by the fact that prey do not always fear human hunters (animals like buffaloes or pronghorn antelopes survived into the modern era alongside humans, despite a reputation of being so bold or so intensely curious that hunters rather easily killed them). It is as reasonable to suggest that Paleoindians played a greater role in the extinctions the longer they were in North America. If only there were numerous archaeological sites with associated extinct megafauna to test Martin's thesis of overkill. But there are only fifty or so sites--a mere handful. At them, Paleoindians killed and butchered mastodons, mammoths, camels, horses, four-horned antelopes, tapirs, and a couple of other extinct species. Amazingly, Martin used the paucity of sites to help buttress his claim that a blitzkrieg marked the onslaught: "Perhaps the only remarkable aspect of New World archaeology is that any kill sites have been found," he once remarked, reasoning from the assumption that Paleoindians killed animals whenever they came across them and therefore the kill sites were scattered and ephemeral. For Martin, a negative (the absence of sites) proves a positive (man killed fearless animals in a blitzkrieg). Martin's unequivocal certainty that man alone was responsible seems remarkable in light of this alone. For Martin's image of restless, relentless Paleoindians to ring true and for the overkill thesis to work, Paleoindians had to be everywhere, required to focus energy and time on megafauna. Unfortunately for Martin, this simply does not fit our most sensible speculations today about Paleoindian adaptations. For too long, archaeologists interested in this period focused myopically, if understandably, on one type of technology referred to as Clovis , whose archetypal artifact is an impressive spear point from three to six inches long and supremely adapted to wounding or delivering the coup de grace to large animals. Archaeologists looking for Paleoindian remains have been attracted most often to bone sites where they have found these fluted points and concluded (not surprisingly) that Paleoindians were hunters, and perhaps hunters only. But we now know that Paleoindian technology cannot be reduced everywhere to spear points used by their makers in an exclusive search for megafauna. And it is inconceivable that in every climate and in every era, the makers of fluted points possessed precisely the same culture or practiced identical gathering and hunting strategies. For some years now the evidence has mounted for very different Paleoindian technologies and adaptive strategies in North America (indeed, throughout the New World). In the West, people used not only Clovis points but also a variety of large and small fluted and nonfluted projectile points. Undeniably, some Paleoindians may have been deliberate or opportunistic hunters of the megafauna that became extinct, but others were probably hunters of caribou, deer, beaver, and small animals. In the tundra, parkland, and mixed forest environments in the East, Indians killed many caribou and some mastodons. But in forested regions, they also exploited species like tortoises--which also disappeared--and other small animals. Many North American Indians were probably generalized foragers whose diet included seeds, roots, shellfish, and fish. In their adaptations they may well have been similar to their contemporaries in Chile, who gathered shellfish and plants and hunted small mammals--and lacked Clovis technology. Because of inadequate or expensive techniques of archaeological recovery, as well as poor preservation, much remains unknown about Paleoindian life, including how near the fit was to our contemporary understanding of hunter-gatherers as people with extensive and variable interest in seeds, fish, roots, shellfish, birds, and other such foods. In the twentieth century, people who gathered and hunted for their livelihood (who provide one way to think about Paleoindians at the end of the Pleistocene) have shown quite extraordinary variation in subsistence and social patterns, especially in environments as different as the various North American ones. Foraging people possess food preferences, but rather than restrict their hunting strategies to single classes of animals, many hunt animals that minimize the cost of their effort relative to their gain. For them, the consequences of hunting for the viability of a species are as likely to be accidental as deliberate. There is no reason to assume that Paleoindians in North America were any different. Of no help either to Martin's argument that only man the megafaunal hunter figured in the Pleistocene extinctions is that minifaunal as well as megafaunal animals vanished. Some were possibly relevant to Paleoindian diets or habits if people were generalized hunters and foragers, and some seem completely irrelevant. Relatively little is known about insects and plants, but at least ten genera (and many more species) of birds disappeared. They ranged widely in size and type from a jay to a flamingo. One was a shelduck, which like other waterfowl was probably easily killed while undergoing molt, when it could not readily fly. Another was a lapwing and no doubt tasty. Other birds included a condor, caracara, and vultures, all probable scavengers of grassland carcasses. There were other raptors, including eagles or hawk-eagles, and jays and cowbirds. Martin tried to explain all the extinct birds away by analogy with contemporary scavenging species in commensal or dependent relations with animals similar to Pleistocene ones that became extinct. But the behavior of the extinct Pleistocene genera was not necessarily identical to that of the living birds presumably related to them. Curiously, approximately the same percentage of birds disappeared as megafauna, even though in Martin's theory Paleoindians were interested only in megafauna. This coincidence alone suggests that we look elsewhere for causes before we conclude that humans alone were responsible for Pleistocene extinctions. The relevance of climate to these events has at times been too casually dismissed. Climate changes were pervasive at the end of the Pleistocene. Temperatures warmed by roughly thirteen degrees Fahrenheit, and the climate became drier overall. Affecting animals and plants more than higher temperatures and increased aridity, however, was probably the rise in seasonal temperature extremes. Winters became colder and summers hotter. In these new conditions, grasses and other plants, insects, and other organisms most directly dependent on temperature and precipitation either flourished or did not, as did invertebrate and vertebrate organisms in turn. Entire habitats changed rapidly at the end of the Pleistocene. In the Upper Midwest, spruce forest became pine forest almost overnight in geological time. For animals with firm boreal forest associations, such as mastodons, the consequences might have been dire. In some areas, grasses withered under drier conditions. With climatic and vegetational changes, small animals altered their distribution, retreating to areas where conditions remained tolerable. Through death or emigration, some animals abandoned the southern, desiccating parts of their ranges; herpetiles (snakes and tortoises) in particular changed theirs. At present, there is much we do not know about the consequences of these climatic and vegetational changes. For some species, there may have been less food. For some, grasses may have become more difficult to metabolize, or even toxic. Perhaps gestation changed. Although hypotheses such as a failure of enzyme systems abound, the causal chain between climate change and extinction remains unclear. The sequences are not clear today. Despite the focus on biotic properties and dynamics, we simply do not know enough about the specific properties of particular extinct forms. We may never know enough. Although much is conjectural, the emphasis on climate and attendant vegetational changes focuses discussion of the extinctions away from communities and on each specific species or genus that changed its range according to its tolerance to the changes. If extinctions are considered on a case-by-case basis, then factors like biomass, reproductive biology, overspecialization, feeding strategies, dependencies, and competition between species come to the fore as being in part responsible for a particular species's vulnerability. Some species have low rates of increase and others high rates. Some have long gestation periods, others short ones. Some have long lives, others brief lives. Some, because of their reproductive biology or social habits, are more vulnerable to extinction than others in a changing climate. The replacement of wet plant communities by dry plant communities in montane habitats will eliminate certain species. Climate changes might have destroyed a particular patchiness in habitat supposedly enjoyed by species like mammoths (on which human hunters also focused their energies). The timing of extinctions was surely important but has not been adequately worked out. Did large grazing animals, for example, become extinct before smaller ones in the same habitat? In large numbers, herbivores weighing over one ton can transform the environment. Once they are extinct, however, the floral composition of habitats can change to affect smaller grazing animals to the point of extinction. That the answers to these questions are currently ambiguous does not mean that they should not be pursued, on a species-by-species, genus-by-genus, habitat-by-habitat, or ecosystem-by-ecosystem basis. Climate presents a formidable obstacle to the exclusionary nature of Martin's thesis. Climate, after all, has been linked to the rapid evolution of mammalian forms. Moreover, in earlier extinction episodes that closely rivaled the late-Pleistocene one but took place long before man the superpredator arrived on the scene, climate overwhelmed plants and animals. Six other extinction events marked the last ten million years in North America. None was caused by Paleoindians, who did not yet exist. But it is a good bet that climate was involved, and there are marked similarities in climatic deterioration and extinctions of the late Pleistocene and the preceding era, the late Pliocene. Even though causation is far from clear, temperature and other climatic and sea-level fluctuations are correlated with these other extinctions, and they and other episodes make extinction seem normal, not abnormal, in the history of life. Indeed, most species that ever lived are extinct. The climatic changes at the end of the Pleistocene alone must have been sufficient to overwhelm certain animals and plants unable to adapt under altered conditions. Desiccation by itself imperiled animals forced to come to the remaining sources of water. Either animals moved to where conditions remained favorable, or they were left susceptible to a Paleoindian coup de grace, or they were weakened to the point of eventual disappearance without helping human hands. If climate fatally complicates the simplistic idea that humans alone were blamable for the extinctions, there is still too much we fail to understand about climate to ascribe responsibility to it alone. Perhaps we will be able to say one day with near 100 percent certainty that climate change triggered interactions that were ultimately destructive to the majority of extinct Pleistocene species. But that day has not yet arrived. In the meantime, because it is naive to think that any single factor was solely responsible for all Pleistocene extinctions, it is safest not to rule out a role for Native Americans altogether. To deny human agency would be as foolhardy as Martin's ruling out climate. Only strict adherence to the belief that modern industrial societies alone cause significant ecological change would lead us to that position. It makes as much sense to hypothesize that Paleoindians pushed certain species already heading toward their doom over the edge to extinction. After all, Paleoindians and a distinctive hunting technology were widespread, and the association of their artifacts with animal remains does show a taste for species now extinct. Another reason for the plausibility of a scenario in which Paleoindians played some role is that preindustrial humans have caused extinctions in other times and places. Throughout the Pacific, indigenous people had a severe impact on birds. They exterminated literally thousands of species well before the arrival of Europeans. The Hawaiian archipelago presents a classic case. There, native people altered the habitat so that it met their needs and conformed to their cultural expectations--so thoroughly that extinctions followed in their wake. Ancient Hawaiians cleared land with fire and diverted streams for irrigation, and crop plants and extensive grasslands took over what had been forested coastal areas. Fish ponds emerged where there had been mudflats. Hawaiians introduced dogs, pigs, chickens, and--inadvertently--rats and reptiles that had stowed away on their canoes. As a result of these introductions and radical changes in the habitat, over forty species of birds (well over half of all endemic bird species) became extinct. Some, especially those that could not fly, the ancient Hawaiians ate: petrels, flightless geese, ibises, rails, a hawk, and crow. Others like honeycreepers, other finches, and a thrush vanished as their habitats disappeared or as their feathers came into demand to ornament clothing. New Zealand presents a second compelling case. As in Hawaii, early Polynesian colonizers--the predecessors of today's Maori--deployed fire to transform New Zealand's environment. They also hunted at least thirteen species of moas--ostrich-like flightless birds, one of which towered over men and women--to extinction. They killed adult birds in large quantities and gourmandized their eggs. They left necks and skulls unused--wasted parts they discarded. In the end, no moas survived, and these ancient Polynesians turned their attention to what was left--shellfish, fish, seals, and small birds. The human hand is deeply implicated in the extinction of avifauna in Hawaii, New Zealand, and other Pacific islands. Of course, North America is not a small island. Nor were Paleoindian societies organized or structured in the same way as early Polynesian ones. Nor do we imagine that Paleoindians transformed or fragmented habitats, or introduced predators, as early Hawaiians did. Nevertheless, a human role should not be ruled out in any case, and there is no good reason to bar humans from at least a supporting part in North American Pleistocene extinctions. Perhaps the very large island of Madagascar provides a better model than smaller islands for what happened at the end of the North American Pleistocene. After the Indonesian--East African ancestors of the Malagasy settled Madagascar, large flightless birds, giant tortoises, hippopotami, more than fifteen species of lemurs (some of which were the size of gorillas), and other animals disappeared. Although some have blamed humans alone for this loss, it seems more likely that men and women arrived on this island at a moment of drought in a long-term climatic cycle oscillating from wet to dry, and that this in combination doomed more species than either humans, desiccation, or vegetation changes alone could have. In view of the evidence that recently came to light to support these island cases, Martin's theory that humans played a significant role in Pleistocene extinctions in North America may be more readily understood, but his continued assertiveness insisting that theirs was the only role that mattered is not. The evidence for the human role in the late-Pleistocene extinctions is circumstantial, and climatic change was fundamental and potentially far-reaching. There is still much we do not know about how and why animals responded to climate changes, but on Madagascar and Hawaii and other Pacific islands, both climate and human-induced changes played a role in the demise of animals. Multiple causes provide the best explanation. Vine Deloria, Jr., recently spoke contemptuously of "mythical Pleistocene hit men" (and angrily vilified scientific methodology and authority), preferring in their place earthquakes, volcanoes, and floods of Indian legend. He theorized that such catastrophes not only occurred but somehow had continental reach to cause the extinctions. But the Pleistocene extinctions continue to defy soundbite simplification. Closer to the time when a fuller historical record can significantly inform interpretation, we turn to a case that also involves disappearance, not of animals but of people: the Hohokam, who lived in urban communities where Phoenix and Tucson sprawl today in the Arizonan Sonoran Desert. Copyright © 1999 Shepard Krech III. All rights reserved.
