I think there has been a lack of imagination about how ancient humans lived and survived. In addition to missing, until recently, the awareness that throughout human history humans have persisted through enormous climatic changes (one ice age after another), we have also imagined how ancient humans lived by comparing them to the few remaining hunter gatherer societies remaining on earth. By the time human studies and anthropology and archeology came into being as specific fields of study (no earlier than 1850 and really not until around 1900) most hunter gatherer groups had been decimated by disease, encroachment, and crowding. When I was in graduate school in 1970 some papers appeared contradicting the belief that ancient human groups spent all their time foraging for food, or hunting, frequently starving, always desperate and stressed. Studies of the Kalahari Bushmen in Africa, near the Kalahari desert in Botswana, demonstrated that in fact they lived pretty well – hunting one or two days a week, gathering foods a few days a week, and spending a lot of time socializing and telling stories. Researchers were also astonished to find that, once infant and childhood deaths were accounted for, adults lived to the same age as modern humans. So the belief was either that ancient tribes struggled always, or, perhaps, actually lived a nearly suburban life.
While it may well be that ancient tribal groups lived very much as the few remaining hunter gatherers today live, what seems to be missing is that the major difference between now and then is that back then the great animals were thriving – mammoths, mastodons, and great sloths could be found nearly everywhere, as could their predators. And what predators they were – great lions larger than modern lions, huge saber tooth cats, dire wolves standing four feet at the shoulder and weighing 200 pounds, and short face bears, carnivorous bears weighing a ton, able to run 40 miles an hour, and reaching as high as 15 feet.There were big hyenas and other carrion eaters, too. In fact, attached below, a mass grave of Neanderthals was just found destroyed by what are believed to be a pack of hyenas, yet even this article misses the main point.
Where I think the lack of imagination lies is understanding how ancient humans must have responded to these animals. Humans are small, weak, and slow, though their endurance over long distances is perhaps the best of any animal on earth, and there is even one theory stating that ancients hunted big game not by attacking that game but by running it down, harrying it again and again until it collapsed with exhaustion. Whenever a human wandered the plains or forest, he or she wandered in territory used by the great predators. Yes, groups gathered together with burning firebrands might have been able to take on a pack of dire wolves, but just as surely the wolves would have had their day. Humans had to find places that were safe from these predators, and safe for long periods of time, because years were needed to raise a child to adulthood, to grow and learn what was needed for survival – at least 13-15 years, probably longer. Every time a group moved, they were vulnerable to attack. If they chose to remain in one place, say a big cave, they needed to range far and wide for game and foods, also vulnerable to attack. Life was always risky, and dangerous, and harsh, and the most dangerous elements were the great predators.
This suggests to me that early humans, all the way up to the end of this last ice age and the beginning of agriculture, must have chosen to find places to live that were, to the degree possible, isolated from easy attack yet near sufficient food for survival. The only such places I can imagine would be along the shore, the seashore or a great lake, on a nearby island, separate from the mainland but with the mainland accessible for hunts, and close, too, to marine resources such as shellfish and fish. On the mainland, such a secure place would be a cave, something with a relatively narrow entrance that could be guarded with fire and spears, but the most secure places would be nearshore islands with marine resources and access to nearby mainland game.
What does this suggest? First, that it is likely that those groups of humans living inland might often have been destroyed, again and again, over thousands of years. Second, that any groups living along the seashore on nearby islands had a better chance of long term survival, but we will never know because the places they lived, the seashore and islands, have long been buried by the rising seas as there last ice melted. And, third, and to me most important, when those groups along the shore felt the need to find new resources, they followed that shore, island to island, over the centuries, and this suggests that the first long human migrations were along coasts, not the interior.
If this is the case, and I believe it is, then throughout human history, over the many times land bridges appeared with the coming of the ice, it is highly likely that humans traversed those land bridges, including the one between Eurasia and the Americas. And, if humans lived along the shore on islands, then from their very beginnings they used boats, initially hollowed out trees to make canoes, to follow that shore wherever it led.
The first real humans, it seems, were Homo Erectus, erect man, who survived nearly two million years, maybe until nearly the present, eventually either merging with later humans or dying out (I think merging is much more likely). Slightly smaller than we humans today, with a smaller brain case, Erectus used fire and has been found in Africa, Europe, Asia, and Indonesia. Some believe Erectus used canoes. Later species, or subgroups, of humans, with larger brains, also used fire and boats. But during all this time, those two million years, in addition to over 20 ice ages coming and going, until the last 10,000 to 12,000 years those humans all shared the earth with the great predators. These great and terrible animals must have been the defining control on humans, the factor that kept the human groups small, distant, often unsuccessful. Only with the end of this last ice advance, as sea levels rose and agriculture emerged, and as the great animals became extinct, did humans overrun all the earth. But, for over 99 percent of our history, if this thesis is correct, humans were restricted to those isolated places that could be considered safe – islands, maybe even glacial refuges among the sheets off ice.