Humans are an African primate. Darwin inferred that Africa was the cradle of mankind because it was the land of our closest relatives: the great apes. All living hominoids, including us, evolved in the tropics, and with the exception of modern humans, no living hominoid is capable of surviving the cold. Gorillas, bonobos and chimps all live in Africa and orangutans, gibbons and siamangs live in southeast Asia.
Apes first appear in the fossil record 25 million years ago in sub-Saharan Africa, so the hominoid body has had tens of millions of years to become perfectly, exquisitely, well-suited to tropical life, so any hominoid that dared to leave Africa and face the bitter cold of the ice age, needed to be incredibly adaptable to survive an environment so opposite of what his ancestors spent 25 million years specializing in. It’s likely that such rapid adaptation could not occur until the hominoid brain reached a certain size, giving us a high capacity to learn, invent, and create culture.
This was the transition from ape to man. Indeed the ability to survive the freezing cold seems to be what separates humans from the apes. For centuries people have speculated about a giant bipedal ape surviving in the Pacific Northwest, but the fact that sasquatch is just a myth further shows that apes can’t survive the cold.
When in our evolutionary history did we become smart enough to do so?
“Humans” first entered Europe 1.8 million years ago, but there’s no evidence we were smart enough to survive Northern Europe until 780,000 years ago, when the climate was similar to today’s southern Scandinavia, and it’s only within the last 40,000 years that humans have proved able to survive the arctic.
Of course even once humans evolved the intelligence to survive the cold, some could survive it more efficiently than others, and as commenters MeLo and Phil78 have pointed out, competition may have been the decisive variable. But competition may have been especially intense precisely because it was cold and thus there were fewer natural resources, while in the tropics, selection pressures were more relaxed because there was less need for shelter and more food to go around.
A 2010 article in the guardian describes archaeologist Brian Fagan’s view that Neanderthals lacked the cognitive ability to adapt to the cold as creatively as modern humans:
This meant, says Fagan, that we learned to use local materials – antler, bone and ivory – in ways Neanderthals simply could not imagine. In one case, this resulted in “one of the most revolutionary inventions in history: the eyed needle, fashioned from a sliver of bone or ivory,” he adds. While Neanderthals shivered in rags in winter, humans used vegetable fibres and needles – created by using stone awls – to make close-fitting, layered clothing and parkas: the survival of the snuggest, in short..
In 2012, paleoanthropologist Rick Potts said:
Whenever glacial habitats invaded Europe and Asia, it appears that the Neanderthals moved south, into Iberia and the Italian peninsula, to take advantage of the warmer places. Overall, their bodies show evidence of cold adaptation. Yet during one cold period, when the Neanderthals retreated, populations of Homo sapiens began to infiltrate the cold regions. How could they do this, especially since these populations were dispersing from tropical Africa? The difference is that these early populations of our species had developed the ability to invent new tools, like sewing needles that were useful in producing warm, body-hugging clothing.
In a 2013 article in the BBC, Oxford university professor Robin Dunbar is quoted as saying the following about Neanderthals:
They were very, very smart, but not quite in the same league as Homo Sapiens. That difference might have been enough to tip the balance when things were beginning to get tough at the end of the last ice age
If temperatures drop 5-10 degrees in Africa, you’re not going to die; there may be changes in rainfall and desert and forest and so forth, but that temperature drop probably won’t kill you.
In Britain, or Siberia, these populations were constantly under pressure. When it was really cold, they were surviving in pockets in the south—in the Iberian Peninsula, the Italian peninsula, the Balkans, maybe in India and Southeast Asia. All the area to the north would empty of people. Then when it warms up, people would start to expand north and grow their numbers. But often they only had 3,000 years before the temperature dropped all the way back again. So I think it is the climate that was shutting down the diversity of those populations; they couldn’t maintain large numbers because of the climate wearing them down.
In March 2015, Chris Stringer told Oxford university that when the ice age got really bad, all humans in Britain simply died out (see 17:20 mark of the Oxford podcast) and Britain had to be recolonized.
And as I noted back in July, The BBC wrote in 2016:
…Neanderthals, with their shorter and stockier bodies, were actually better adapted to Europe’s colder weather than modern humans. They came to Europe long before we did, while modern humans spent most of their history in tropical African temperatures. Paradoxically, the fact that Neanderthals were better adapted to the cold may also have contributed to their downfall.
If that sounds like a contradiction, to some extent it is.
Modern humans have leaner bodies, which were much more vulnerable to the cold. As a result, our ancestors were forced to make additional technological advances. “We developed better clothing to compensate, which ultimately gave us the edge when the climate got extremely cold [about] 30,000 years ago,”…