[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?]
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MOST HUMANS HAVEN’T EVOLVED TO COPE WITH THE COLD, YET WE DOMINATE
NORTHERN CLIMATES – HERE’S WHY  
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Laura Buck, Kyoko Yamaguchi
January 16, 2023
The Conversation
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_ 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? _

Humans have used technology to adapt to the cold. , Yvette Cardozo /
Alamy Stock Photo

 

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
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and eastern Africa
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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
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wind chill that exacerbated heat loss
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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.

[Woman warming her hands with cat next to space heater]Many humans
dread the cold of winter. Mariia Boiko/Shutterstock
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The earliest signs of hominins living in northern Europe are from
Happisburgh in Norfolk
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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
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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
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contentious. Tools for tailoring fitted, weather-proof clothes
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don’t appear in western Europe until almost 850,000 years later.
Many animals migrate to avoid seasonal cold, but the Happisburgh
hominins
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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
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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
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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
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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 [[link removed]] 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
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Larger bodies
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relatively short limbs
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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
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this period.

Cold climate specialists

The Neanderthals, who lived in Eurasia about 400,000-40,000 years ago,
inhabited glacial climates
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Compared to their predecessors in Africa, and to us, they had short,
strong limbs
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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
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living in cold areas and lab rats
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in cold conditions, living humans from cold climates
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tend to have relatively high, narrow noses and broad, flat cheekbones.

Computer modelling
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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 standing in the snow.]Musk ox are well adapted for cold
weather. Fitawoman/Shutterstock
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Even with their cold-adapted physique, Neanderthals were still hostage
to their tropical ancestry. For example, they lacked the thick fur
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of other mammals in glacial Europe, such as woolly rhinos and musk
oxen. Instead, Neanderthals developed complex culture to cope.

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

More controversially, some archaeologists say
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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
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as well as the pygmy slow loris [[link removed]] in norther
Vietnam.

[A lesser bushbaby seen feeding on tree resin on a safari at night in
South Africa]Lesser bushbabies are one of the few primates that
hibernate. Rudi Hulshof/Shutterstock
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This might give you the idea that humans can hibernate too. But most
species that hibernate have small bodies
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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 [[link removed]].
But we didn’t spread out of Africa until about 60,000 years ago
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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
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synthesising vitamin D. The genomes of living Inuit people from
Greenland demonstrate physiological adaptation to a fat-rich marine
diet [[link removed]], 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 [[link removed]] 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
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insulation than the modern Canadian army winter uniform.

This human ability to adapt behaviourally was crucial to our
evolutionary success
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other primates [[link removed]],
humans show less physical climatic adaptation. Behavioural adaptation
is quicker and more flexible than biological adaptation. Humans are
the ultimate adapters [[link removed]],
thriving in nearly every possible ecological niche.[The Conversation]

Laura Buck [[link removed]],
Senior Lecturer in Evolutionary Anthropology, _Liverpool John Moores
University
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and Kyoko Yamaguchi
[[link removed]], Senior
Lecturer in Human Genetics, _Liverpool John Moores University
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This article is republished from The Conversation
[[link removed]] under a Creative Commons license. Read
the original article
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* Science
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* humans
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* Evolution
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* Climate
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* evolutionary biology
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* Technology
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