34 | New Scientist | 28 September 2019The final frontier
The Americas were the last continents conquered by humans, and we’re finally
discovering more about the pioneers who did it. Colin Barras investigates
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S
OME 15,000 years ago, a small band of
pioneers stood on the threshold of a new
world. To the south were the Americas,
40 million square kilometres of virgin territory
including wide-open prairies, dense rainforests
and high mountain chains. An epic journey
was about to begin – but only because a
remarkable adventure had just ended.
Before these original American frontiersfolk
ventured south, their forebears had spent
millennia scratching a living in the desolate
regions just south of the Arctic circle.
Once they had arrived in the north, global
temperatures plunged and the climate
became bleaker still.
Faced with worsening conditions, these
original pioneers stayed put, spending
thousands of years isolated from the rest of
humanity. Their fate is now coming to light,and it is clear that something remarkable
happened during those missing years. The
people who would eventually conquer the
Americas evolved some unusual adaptations
to survive, and it turns out that this genetic
legacy can help trace their descendants today.
We don’t know exactly when humans first
reached the New World. The consensus is that
the first Americans arrived fairly recently,
about 15,000 years ago. It is also widely
believed that they did so via Beringia – an area
centred on the Bering Strait between Siberia
and Alaska, which was dry land at that time.
This implies that the story of the first
Americans began with a subarctic odyssey.
Whereas Europe and Asia has been home to
hominins for almost 2 million years, it seems
none of the earliest inhabitants – including
Homo erectus, Neanderthals and Denisovans –strayed much above 55° north, roughly in
line with the top of what are now Ireland and
Kazakhstan. “There’s every reason not to do
it,” says Ben Potter at the University of Alaska
Fairbanks. It isn’t just cold. There aren’t as
many animals at higher latitudes, making
hunting difficult.
On current evidence, modern humans,
rather than our extinct relatives, were the first
to enter northern Eurasia. John Hoffecker at
the University of Colorado, Boulder, suspects
that key inventions opened up this subarctic
region. Tailored clothing was probably
necessary to cope with cooler conditions.
And snares offered a solution to sparsely
distributed prey. Used by modern Arctic
inhabitants, they are essentially automated
hunting devices that operate 24 hours
a day, helping people exploit territories