There are some strange things about the extinctions of animals over the last 50,000 years. Why was it that in the American continents the large animals had a major extinction event shortly after the time that the Clovis people appeared? The easiest explanation for the extinction is that the Clovis people killed those animals and ate them. But how could a few boatloads of people from the old world eat a whole continents worth of big animals? The answer is that a free breeding population can grow geometrically if there is enough food just like Thomas Malthus suggested.
About 11,500 through 10,000 years ago still during the last ice age human big sea mammal hunters arrived in North America, probably from northern Japan by boat and flowed over onto the land. A group of hunter families such as the Ainu, known in America as Kennewick Man, who were practiced at large animal predation probably arrived and in 1,500 years brought about the extinction. The process is straight forward and relatively easy for these people to do because the animals would have no natural fear response to the presence of humans. Thus a hunter with experience killing large sea mammals such as seal or even walrus would find a friendly American horse, camel, llama, mammoths and many other large herbivores virtually walking up and offering themselves for dinner. The Ainu had all the tools necessary for the work of killing these large animals and for several centuries they simply ate their way across the American continents with a continually exploding population of humans needing more food. It was probably rather like our present time with an absolute abundance of everything necessary for the prevailing life style. For the Ainu people carrying Clovis style killing tools, it was heaven on Earth. The human population exploded to some large number before there was any food problem. Their numbers grew to well beyond the sustainable carrying capacity of the large animals ability to reproduce themselves and supply the people with their meat. When that happened there was a rapid hunting to extinction of what few animals remained by the overabundant number of humans. The period of time when there were large numbers of people would have been only a generation or two because with an unlimited supply of food the population would double very quickly and eat be every one of their prey species available. When the big animals were gone the Ainu tried to live off of the smaller animals but there whole culture was designed for living off of the large species and so there was an abrupt human population collapse. Agricultural knowledge brought from Japan with the first hunters would have been lost in the 1,500 year long meat feast. Because the rise and fall of the human population happened so quickly the total number of humans to have lived in the Americas was quite small. About that same time when the big herbivores became scarce the big carnivores, who probably only preyed upon certain species and hadn’t developed a taste for humans, soon found themselves with nothing to eat and died of famine. The humans, after the demise of their prey, soon retreated population wise to very small numbers and perhaps extinction in some localities which coincided with the demise of the of the other large animals. These were hunters, they were not farmers and they may have had no developed sense for eating anything other than what they grew up eating so when that was gone they were gone.
The other non-African continents had similar but milder experiences because the humans came on a little slower and the prey animals had some time to acclimate and develop appropriate strategies for coping with them. Africa is a special case because that is where humans arose over the course of hundreds of thousands of years and the animals had opportunity to learn to be fearful of humans and how to cope with them and were successful up to the present. These animals coping strategies had to be transmitted genetically and so it was a survival of the fittest type of survival which is very slow compared to what humans were capable of, which is verbal transmission of how to hunt various animals. Asia is an in between zone where some animals in remote places survived longer and adapted better and didn’t go extinct so quickly. However, even in America there were some animals which because of their natural habitat were difficult to kill and so survived. The bighorn sheep live in very inhospitable mountain retreats and probably were there to avoid the pre-human predators such as the big cats and bears. They survived the human onslaught simply because they lived in places were they were too difficult to hunt. The other survivors may have similar qualities which helped them survive. Possibly the bison survived because of their habits of traveling in huge herds great distances between pastures and they moved more rapidly than the hunters could follow them. The bison’s strategy for survival may have to avoid predation by wolves but it saved their species from humans also. Not because of their fear of humans but simply because there so many of them moving so rapidly that only a very few were taken by hunters. Until the American Indians had horses the buffalo were a real challenge to cope with, no doubt.
It seems the American experience may have been that before the Clovis culture there may have been a few people but they were very marginal to the overall ecosystem. Without good weapons they have been more prey than predator. Then came the well armed meat eating Ainu with everything they needed to prey upon the mega-fauna, which they did and soon multiplied to where they literally ate themselves out of a continent sized food locker and died. Then with the flow of people on foot across the Arctic came a broader based life style which at least had the potential for farming and animal husbandry. However, by the time they arrived all of the easily domesticatable animals had been eaten by the long gone hunters and were extinct. That is why when Columbus and his followers got to America there were no domestic animals other than wild turkeys, a few dogs, lamas and guinea pigs. Of these only the dogs were actually domesticated and would willingly seek out and live with humans the others were little more than captured wild animals.
I have been reading Admiral of the Ocean Sea by Samuel Eliot Morrison this week and I just realized there was another domesticated animal. The Carib Indians of South America had within the previous hundred years or so, before Columbus arrived, been working there way up through the Antilles Islands. They were cannibals and were literally eating their way through the primitive people called the Taino up the chain of islands when Columbus visited their villages. One of the weirdest things mentioned in that book was that the Carib Indians were keeping young Taino indian women to have babies which they ate as their favorite food. This is a form of domestication only humans could conceive of or perhaps insects.
The pre-Columbian Americans did not have domesticated animals because the local animals which might have been domesticated had been hunted to extinction. If pastoralists had come upon this continent before the hunters there would probably have been large numbers of species domesticated.