Archaeologists have discussed three barriers (fig. 10.3) limiting human colonization of the New World: (1) The northern line of archaeological sites seems to conform to this limit of 60° N, mainly because there was insufficient technology to carry on life in far northern environments. (2) The Bering Strait has been considered a barrier, and some archaeologists have thought that the intermittent land bridge between Alaska and Siberia was the key to colonization. But there are places where one can cross over to Alaska on the winter ice, even without a land bridge. People adapted to life on one side could easily have crossed the few kilometers of ice to the other side. (3) Continental ice sheets did separate Alaska from ice-free regions to the south for thousand of years, but a corridor several hundred kilometers wide seems to have been open when Asian people first arrived in Alaska sometime between 12,000 and 13,000 years ago. Thus (1) seems to have been the obstacle of most significance. However, had these new colonists come 14,000 years ago or earlier, this corridor would have indeed been closed. We can see its pincer effects on the mammal groups it squeezed in two (fig. 10.4).
At its extreme development the Mammoth Steppe seems to have been a hostile environment for early people—winter temperatures and high winds, combined with few woody materials for shelter, fuel, or tools. The otherwise good hunting grounds were bad living grounds. Abundant wood is a necessary part of northern technology. The rivers flow northward in Beringia, however, so the running water may have aided dispersal of seeds (fig. 10.5). The northern barrier was breached, and people moved into land never seen by humans. Something new had happened. We can wager that these first people were bison hunters, as well as hunters of other mammals on the disintegrating Mammoth Steppe.
Not all archaeologists would agree with the timing or some of the interpretation of the above scenario. It is a view that many do accept, and if we proceed with this interpretation of archaeological and paleontological data, we can say that Blue Babe lived in a land untracked by human hunters. During his lifetime, thousands of kilometers to the west and south, however, people were dining on bison almost exactly like Blue Babe. Much later, the first colonists in the Fairbanks area would also be hunting bison, descendents of Blue Babe that were probably very similar to him in some ways.
Fig. 10.4. Laurentide and Cordillerian ice sheets. This barrier separated some species into genetically different, northern and southern forms. Pikas (Ochotona), northern ground squirrels, (Spermophilus), and mountain sheep (Ovis) are three mammals that live and prosper in periglacial conditions. Their present distributions reveal a recent north-south separation. This suggests that the corridor between Alaska and the rest of the continent was closed to virtually all terrestrial Alaskan mammals, including humans if they had been present, during the last glaciation.
Fig. 10.5. Riparian model of woody-plant recolonization of the north. During glacials the northern part of the Mammoth Steppe was virtually devoid of trees. At the onset of the warm-wet interstadial and, again, with the beginning of the Holocene, trees recolonized the far north. The northward flow of these rivers would have assisted rapid colonization. Many northern trees make use of runoff water for seed dispersal.
Predation and Bison Defense Strategy: Pleistocene-Holocene Differences
A well-preserved Pleistocene bison with accompanying paleoecological data offers a occasion to reflect on the behavioral dynamics of human predation on bison in the Pleistocene. How extensive was bison hunting in the Pleistocene, and was it as easy as it later was during the Holocene bison drives on the American Great Plains? Were Pleistocene bison behaviorally similar to living bison, which lack notable ferocity toward humans? Insights about such hunting can be gained by comparing Pleistocene predator-prey strategies (based on information we have from Blue Babe) and the present.
When Blue Babe was found we carefully excavated the carcass, collecting surrounding sediments and wet screening them for associated artifacts, since there was the possibility that the mummy was part of an archaeological kill site. As it turned out it was not, but any late Pleistocene large-mammal carcass or special accumulation of bones should be excavated with the possibility in mind that it may be an archaeological site. In fact, most paleontological sites are now excavated by the same techniques and seek the same kinds of paleoenvironmental data as archaeological sites.
The entry of African hominids into Eurasia roughly corresponds to the rise of bison as a genus. A rather straight-horned creature called Leptobos was the early ancestor to most bovines: cattle, buffalo, bison, and so forth. Leptabos occurs in the earliest Pleistocene of Europe and Asia. Later in the Pleistocene (a little less than a million years ago), the first animals that we could call bison appeared. Like later bison, these were bovines with rugged skulls. Their horns emanated from the sides of the skull, and eye orbits telescoped out away from the skull.
The first Homo colonists arrived in Eurasia at a time of major fauna change, when the more primitive “Villifranchian” fauna of Eurasia was being replaced by the “Galerian” fauna (Turner 1982; Azzaroli 1983). Villifranchian large mammals, including the three-toed horse, Hipparion, and the primitive bovine mentioned above, Leptobos, were more Tertiary-like in their appearance, The Galerian fauna was more “modern” and persisted relatively unchanged in overall character until the end of the Pleistocene.
This change in faunas was major. New elements from the Americas, such as true horses (Equus), dispersed into Eurasia and Africa from Beringia. Also at this time African species, for example, lions (Panthera leo), dispersed throughout Eurasia. Hominids came along in this faunal movement up from Africa (Turner 1982). Timing of the Galerian Dispersal event is still not precisely clear. Azzaroli (1983) proposes that it happened before the last major pole reversal (before the beginning of the Bruhnes normal epoch), sometime before 700,000 years ago.
These first Eurasian hominids were not our own species. They have sometimes been referred to as Homo erectus. They had rather simple tools, and evidence suggests they had begun to use fire rather early in their occupation of Eurasia. They were ruggedly build, with a brain size smaller than that found today among any living peoples, but in many respects they were similar to modern peoples. These earliest Eurasians probably shared communities with bison, as some of the oldest bison records are rather far south (India). Bovine niches were soon divided latitudinally in Eurasia. Bison evolved as northern-adapted bovines, while the southern bovine niche was occupied by not-too-distant relatives: cattle (Bos) and buffalo (Bubalus) species.
Neanderthals were the first consistent hominid predators of bison. Neanderthals replaced early hominids in Eurasia (or were derived locally from them) during the last interglacial, about 120,000 years ago. Some authors would call Neanderthalers Homo sapiens, but Neanderthals were anatomically distinct from modern peoples, despite many similarities. Their brain size was as large if not larger, than living peoples, but like Homo erectus, they were very ruggedly built, even more so than Homo erectus. Neanderthal tool kits, at least the ones that were preserved, were also relatively simple, although more diverse than Homo erectus. The lithic industry associated with Neanderthals is called Mousterian; it is based on flakes as opposed to a core technology of Homo erectus.
Neanderthals were not bison-hunting specialists; judging by their bone refuse they hunted larger mammals, such as mammoths, rhinos, and horses, as well as bison. Bison bones in Neanderthal sites are usually thoroughly smashed, presumably to make complete use of the marrow. Neanderthals seldom made use of bone, ivory, and antler for tools, and despite hundreds of sites, there is no evidence Neanderthals ever used ornamentation. Neanderthals ranged rather far north during the interglacials and interstades, but during the glacial maxima 80,000 years ago (isotope stage 4) they were probably pushed far south. They occupied Europe and Asia widely during the interglacial of 100,000 years ago (isotope stage 5) and the interstadial centering around 40,000 years ago. Blue Babe was a contemporary of the last Neanderthals.
Between 35,000 and 40,000 years ago,
Neanderthals were replaced in Europe by anatomically modern peoples; in Asia this change may have occurred a little earlier. These new peoples began to use long blades struck from stone cores instead of stone flakes. Ornaments of many kinds appear in the sites, especially the elaborate use of bone, ivory, and reindeer antler as a tool and artistic medium. The newcomers ranged farther north than had preceding peoples, well into the domain of bison. And bison occur in many of their sites. But with the exception of a few areas far to the south in the Caucasus (Vereshchagin 1959), there are few sites where bison predominate. Although there are numerous Eurasian Pleistocene archaeological sites where horses, reindeer, and mammoths make up almost the entire bone assemblage, bison seldom do. However, bison are present in low abundance in many sites of late Paleolithic age.
This same bison-use pattern continues during and after colonization of the New World. For example, there are no Clovis sites in the Americas where bison bones predominate. Clovis people seem to have hunted bison, yet not in great numbers. At the Dry Creek site near Healy, Alaska, which dated around 11,000 years ago, Roger Powers, John Hoffecker, and I found bison associated with stone microblades, sometimes only a little over a millimeter thick and less than an inch long (fig. 10.6). These miniature blades are struck from a small core (fig. 10.7). We know from sites in Siberia that such little blades could be inserted in the side of an antler or bone shaft to provide a cutting edge. Bone and antler points penetrate well, but without a stone cutting edge these do not cause enough bleeding to make an animal die quickly (Guthrie 1983). These microblades, their microcores, and/or small biface stone projectile points, and small burins apparently for working osseous projectile points are a characteristic signature of lithic assemblages across the north at the end of the Pleistocene. This style of stone technology, called Beringian tradition by West (1981), is found over an enormous area: Alaska, the Yukon Territory, eastern Siberia south into China, northern Japan, and across much of northern Asia. Similar technologies (including microblades) are found farther west to the Urals and on into Europe (fig. 10.8). But this does not necessarily mean that these areas were inhabited by the same peoples; undoubtedly the technique crossed biological and cultural lines. Bison are associated with many of these sites, but the microblade sites fit the general picture of the sites with a few bison bones; in no site are bison bones dominant.
Fig. 10.6. The Dry Creek site. Bison were present in the Dry Creek site in central Alaska, which dated around 11,000 years ago. Work at other sites will help us understand the role of Mammoth Steppe fauna in the lives of these first North Americans.
Fig. 10.7. Small stone cores used to strike microblades. This illustration shows (left) a blank core before microblades have been removed and (right) an exhausted core to produce more microblades. Near the exhausted core we also found the large flakes struck to produce the table from which the microblades were made. These flakes are glued back into place. Both specimens are from the Dry Creek site, which is about 11,000 years old.
In one Siberian site, Kokorevo, a composite projectile point of reindeer antler and microblades (fig. 10.9), was found sticking in the scapula of a bison (Abramova 1982)—solid evidence that people were hunting bison with this kind of weapon. Gönnersdorf, a site in northern Germany (Bosinski 1981), contained bone evidence of at least two bison and a sketch of a bison face scratched in stone. Gönnersdorf also contained microblades not too unlike those in the Dry Creek site in Alaska. The Berelekh archaeological site on the Indigirka also contained microblades and bison bones. Most of these sites with microblades and bison bones date from 13,000 to 10,000 years ago, and perhaps a little earlier and later.
Fig. 10.8. Association of microblades and bison, 13,000–10,000 B.P. Within the range of B. priscus (dashed line), a hunting technology expanded across the waning Mammoth Steppe. The tools included burins, small stone projectile points, and rectangular microblades that apparently were inset into caribou-reindeer antler points. This technology obviously was part of several cultures and racial stocks. The sites shown here (from 11,000 to 13,000 years old) contain both bison remains and microblades.
Fig. 10.9. Bison hunters and microblades. A reindeer antler projectile point with small grooves for microblades was found protruding from a bison scapula in the Kokorevo site in Siberia, illustrating that early Beringian people used such tools to hunt bison.
People seem to have been colonizing the far north at this time; it was a time of waning continental ice, increasing moisture, decreasing wind, and invasion of the north by shrubs and trees, producing a climate more habitable to humans. People using stone projectile points and microblade technology spread northward during the late glacial, hunting different species of the mammoth fauna. They persisted in that hunting mode after many of these species were completely extinct (e.g., woolly mammoth and woolly rhino) or regionally extinct (e.g., horse and saiga).
Several paleoecologists have argued that humans were instrumental in causing these extinctions (see Martin and Klein 1984 for a review of this subject), but the actual causes of extinctions in the far north, both regional and complete, are difficult to reconstruct because climate and vegetation were changing dramatically at the same time. Even if humans had not been present, most of these large-mammal species could not have survived the vegetational changes and increasing snow depth (Guthrie 1982).
Although I have argued that the large-mammal (horse, mammoth, etc.) extinctions in Beringia were a product of changing climate (Guthrie 1982, 1984b), a forceful argument has been made that these mammals were killed off by the new human immigrants from Asia. However, there are many problems with the “overkill” explanations of mammalian extinctions in Alaska; for example, it is unlikely that the demise of saigas, badgers, and black-footed ferrets can be explained directly by the incursion of human hunters.
Bison survived the extinction of many other large mammal species in the central North American continent. Bison numbers may have even increased (fig. 10.10) in the Holocene as a by-product of the reduction of species diversity and hence decreased competition. The immense bison herds on the Great Plains seem to be unique to the Holocene.
Bison seem to have also survived Pleistocene extinctions in Alaska and western Beringia (Vereshchagin and Baryshnikov 1984), while mammoths, horses, helmeted musk oxen, camels, and others died out in the far north. Bison survived because small patches of bison habitat remained in interior Alaska, as discussed earlier. Bison were probably hunted until the time of their demise, a few hundred years before the present, not long before Europeans and firearms entered the far north.
Fig. 10.10. The effect of megafaunal extinctions on bison numbers. In the lower graph the number of radiocarbon dates on bison from the continental United States is plotted against time. Prior to 12,000 years ago, there are few dated bison fossils. This number, however, rises sharply at 11,500 to about 7,000 years ago. I suggest this is a response to the disappearance of other grazers (Mammuthus, Equus, etc.) lost in late Pleistocene extinctions. The decrease in bison on the Great Plains between 4,000 and 7,000 years ago is probably due to the aridity of the Hypsithermal.
Thus bison experienced two quite different evolutionary contexts in the late Quaternary. Bison had originated in, and shared for almost a million years, a complex community of large predators and grazing competitors which changed abruptly about 11,000 years ago, at the Pleistocene-Holocene transition. These quite different evolutionary contexts produced two different kinds of bison, and I have argued that this watershed made for different anatomical optima (Guthrie 1980). And indirectly, Blue Babe’s death contributes some insight into the response of bison to human hunters.
I discussed the comparative rarity of bison in Paleolithic and Clovis archaeological sites, yet bison remains dominate many Holocene sites. Bison are a common fossil and also a very common subject of Paleolithic art. Few caves with Paleolithic drawings lack bison pictures. Judging from these artworks and paleontological sites, bison seem to have been numerous, but hunted onl
y lightly.
Neither American nor European bison are today particularly dangerous animals. They can be hunted without fear of being gored and killed. American plains Indians hunted bison and killed them by the hundreds with a variety of techniques. Bison of the Great Plains were not considered very dangerous. Their usual response to humans, even when mortally wounded, is to run. In that regard they are quite different from the African buffalo, Syncerus, which is one of the most dangerous of large mammals. When African buffalo are wounded, bulls frequently charge in violent attempts to kill their human hunters, and often the bulls succeed. African buffalo and bison species are within the same size range and same general ecological niche, yet their behavior in this respect is markedly different.
I propose that African buffalo are so fierce because lions are their major predators (Sinclair 1977). African buffalo cannot simply run away from lions; they must use strength and ferocity to ward off predation. Indeed buffalo occasionally kill lions (Schaller 1972). To take a buffalo, a lion must first throw the buffalo to the ground by grabbing hold and dragging it down, before the lion can actually kill the buffalo by strangulation. In a one-on-one situation a buffalo can turn toward a lion and use its sharp horns for defense. A fierce retaliation of horn goring forms an important deterrent to any but a very desperate lion. Lions must be judicious in their choice of prey; they can only attack in situations where they can make a kill and still have very little chance of self-injury (fig. 10.11).
For modern bison the situation is different. For more than 10,000 years bison have lived without any predator as large as a lion. Their only potential predators have been a large solitary cat (Felis concolor) and a social wolf (Canis lupus). Defense against wolves is quite different than defense against lions (fig. 10.12). It is unlikely that a bison could reasonably expect to catch and gore a wolf if it were to try to turn the attack, and even if caught, wolves are small enough that a hook with horns and head butt could not be expected to cause the same degree of damage. Unlike lions, wolves do not grab a bovine and try to throw it off of its feet; rather, wolves kill very large herbivores by a drawn-out series of quick attacks to the rear, resulting in the accumulation of many traumatic bites in the hind legs and hindquarters, until the animal is finally debilitated and can no longer defend itself from the front. Not surprisingly, the reaction of bison and moose to wolves is flight (Carbyn 1975). That is how they react to human predators as well, even in confrontational situations when wounded (there are some rare exceptions in the literature). Running moose and bison are a windmill of powerful hoofs, too formidable for an easy bite by wolves.
Frozen Fauna of the Mammoth Steppe: The Story of Blue Babe Page 28