Creationism in Crisis - How Humans Evolved to Live in Cold Climates

Creationism in Crisis

How Humans Evolved to Live in Cold Climates

Most humans haven't evolved to cope with the cold, yet we dominate northern climates – here's why

Turku, Finland in Winter

Jarmo Piironem/Eyem/Getty Images

With the exception of only a few, relatively minor, changes to our genome, such as loss of skin pigmentation and changes to hair and eye colour, and the ingression of Neanderthal and Denisovan genes, non-African humans differ little from the first Homo sapiens to venture out of Africa, where they had evolved as a tropical species. Today, humans are the only Great Ape to live outside of the tropics.

And yet we have managed to live in northern climates with shorter days in winter and sub-zero temperatures in which the earliest members of our species would probably not survive a night without special measures.

With our physical and physiological makeup differing so little from our African forebears, what has enabled us to survive in these hostile conditions to which we were so mal adapted? The answer is that an additional layer of evolution is operating alongside genetic evolution - memetic, or cultural, evolution - so-called gene-meme co-evolution.

Memetic evolution has taken us from the bands of hunter-gatherers huddled round a campfire and sheltering in caves and rock overhangs, to a modern urbanised, hi-tec species living in centrally heated buildings or dressing in warm clothing and entirely dependent on science and technology for our survival. Put us naked out in the open on a cold winter night and few of us would survive, let alone thrive, and survival without cloths and shelter would be impossible on the arctic tundra even in summer.

In the following article, reprinted from The Conversation, Laura Buck, Lecturer in Evolutionary Anthropology, and Kyoko Yamaguchi, Senior Lecturer in Human Genetics, both of Liverpool John Moores University, explain how we and our cousin species, the Neanderthals adapted to the very non-African conditions they found themselves in.

The article has been reformatted for stylistic consistency; the original can be read here.

Most humans haven’t evolved to cope with the cold, yet we dominate northern climates – here’s why

Published: January 16, 2023 6.05am GMT

Humans have used technology to adapt to the cold.

Credit: Yvette Cardozo / Alamy Stock Photo

Laura Buck, Liverpool John Moores University and Kyoko Yamaguchi, Liverpool John Moores University

Humans are a tropical species. We have lived in warm climates for most of our evolutionary history, which might explain why so many of us spend winter huddled under a blanket, clutching a hot water bottle and dreaming of summer.

Indeed all living apes are found in the tropics. The oldest known fossils from the human lineage (hominins) come from central and eastern Africa. The hominins who dispersed northwards into higher latitudes had to deal with, for the first time, freezing temperatures, shorter days that limited foraging time, snow that made hunting more difficult and icy wind chill that exacerbated heat loss from their bodies.

Given our limited adaptation to the cold, why is it that our species has come to dominate not only our warm ancestral lands but every part of the globe? The answer lies in our ability to developed intricate cultural solutions to the challenges of life.

Many humans dread the cold of winter.

Credit: Mariia Boiko/Shutterstock

The earliest signs of hominins living in northern Europe are from Happisburgh in Norfolk, eastern England, where 900,000-year-old footprints and stone tools have been found. At that time, Happisburgh was dominated by coniferous forest with cold winters, similar to southern Scandinavia today. There is little evidence the Happisburgh hominins stayed at the site for long, which suggests they didn’t have time to adapt physically.

It’s still a bit of a mystery how these hominins survived the tough conditions that were so different from their ancestral African homelands. There are no caves in the region, nor evidence of shelters. Artefacts from Happisburgh are simple, suggesting no complex technology.

Evidence for deliberate campfires at this time is contentious. Tools for tailoring fitted, weather-proof clothes don’t appear in western Europe until almost 850,000 years later. Many animals migrate to avoid seasonal cold, but the Happisburgh hominins would have had to travel about 800km south to make a meaningful difference.

It’s hard to imagine hominins surviving those ancient Norfolk winters without fire or warm clothing. Yet the fact the hominins were so far north means they must have found a way to survive the cold, so who knows what archaeologists will find in the future.

The Boxgrove hunters

Sites from more recent settlements, such as Boxgrove in West Sussex, southern England, offer more clues about how ancient hominins survived northern climates. The Boxgrove site dates to nearly 500,000 years ago, when the climate deteriorated towards one of the coldest periods in human history.

There is good evidence these hominins hunted animals, from cut marks on bones, to a horse shoulder blade probably pierced by a wooden spear. These finds fit with studies of people who live as foragers today which show people in colder regions depend on animal prey more than their warm climate counterparts. Meat is rich in the calories and fats needed to weather the cold.

A fossilised hominin shin bone from Boxgrove is robust compared to living humans, suggesting it belonged to a tall, stocky hominin. Larger bodies with relatively short limbs reduce heat loss by minimising surface area.

The best silhouette for avoiding heat loss is a sphere, so animals and humans in cold climates get as close to that shape as possible. There is also clearer evidence for campfires by this period.

Cold climate specialists

The Neanderthals, who lived in Eurasia about 400,000-40,000 years ago, inhabited glacial climates . Compared to their predecessors in Africa, and to us, they had short, strong limbs, and wide, muscular bodies suited to producing and retaining heat.

Yet the Neanderthal protruding face and beaky nose are the opposite of what we might expect to be adaptive in an ice age. Like Japanese macaques living in cold areas and lab rats raised in cold conditions, living humans from cold climates tend to have relatively high, narrow noses and broad, flat cheekbones.

Computer modelling of ancient skeletons suggests Neanderthal noses were more efficient than those of earlier, warm-adapted species at conserving heat and moisture. It seems the internal structure is as important as overall nose size.

Musk ox are well adapted for cold weather.

Credit: Fitawoman/Shutterstock

Even with their cold-adapted physique, Neanderthals were still hostage to their tropical ancestry. For example, they lacked the thick fur of other mammals in glacial Europe, such as woolly rhinos and musk oxen. Instead, Neanderthals developed complex culture to cope.

There is archaeological evidence they made clothes and shelters from animal skins. Evidence of cooking and use of fire to make birch pitch glue for the manufacture of tools show sophisticated Neanderthal control of fire.

More controversially, some archaeologists say early Neanderthal bones from the 400,000-year-old site of Sima de los Huesos in northern Spain show seasonal damage from slowing down their metabolisms to hibernate. The authors argue these bones show cycles of interrupted growth and healing.

Only a few species of primate hibernate such as some lemurs in Madagascar and the African lesser bushbaby, as well as the pygmy slow loris in norther Vietnam.

Lesser bushbabies are one of the few primates that hibernate.

Credit: Rudi Hulshof/Shutterstock

This might give you the idea that humans can hibernate too. But most species that hibernate have small bodies, with some exceptions like bears. Humans may be too big to hibernate.

Jack of all trades

The earliest fossils in the Homo sapiens lineage date from 300,000 years ago, from Morocco. But we didn’t spread out of Africa until about 60,000 years ago, colonising all parts of the globe. This makes us relative newcomers in most habitats we now inhabit. Over the intervening thousands of years, people living in freezing cold places have adapted biologically to their environment but on a small scale.

One well-known example of this adaptation is that in areas with low sunlight, Homo sapiens developed light skin tones, which are better at synthesising vitamin D. The genomes of living Inuit people from Greenland demonstrate physiological adaptation to a fat-rich marine diet, beneficial in the cold.

More direct evidence comes from DNA from a single 4,000-year-old permafrost-preserved hair from Greenland. The hair hints at genetic changes that led to stocky body shape that maximised heat production and retention, like the hominin we only have one shin bone from the Boxgrove site.

Our tropical legacy means we would still be unable to live in cold places without developing ways of coping with the temperatures. Take, for example, the traditional Inuit parka, which provides better insulation than the modern Canadian army winter uniform.

This human ability to adapt behaviourally was crucial to our evolutionary success. Even compared to other primates, humans show less physical climatic adaptation. Behavioural adaptation is quicker and more flexible than biological adaptation. Humans are the ultimate adapters, thriving in nearly every possible ecological niche.
Laura Buck, Lecturer in Evolutionary Anthropology, Liverpool John Moores University and Kyoko Yamaguchi, Senior Lecturer in Human Genetics, Liverpool John Moores University

Published by The Conversation.
Open access. (CC BY 4.0)

It's hardly worth mentioning really, but there is no sign at all that the scientists think the Theory of Evolution is not fit for purpose anymore and are about to abandon it in favour of one involving magic and unproven supernatural entities. In fact, the TOE is fundamental even to our understanding of how human cultures developed and why, with a large enough brain and the ability to learn and pass on information, humans are no longer dependent on purely genetic evolution to adapt to change and exploit new opportunities.

What differentiates us from our archaic forebears is not so much our genes but our evolved cultures. The astonishing thing is that some people who live in and benefit from our evolved cultures continue to insist there is no such thing as evolution.

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