“Multiple
lines of evidence suggest that the ancestors of most humans living outside
Africa left the continent in one migration 60,000 years ago. But there is some
evidence that pioneer modern humans (Homo sapiens) made forays outside Africa before this time.
In
January, scientists unveiled the jawbone of a modern human
who died in Israel 185,000 years ago, tens of thousands of years
earlier than previous evidence. Received wisdom suggests that these earlier
excursions failed to provide modern humans with a permanent foothold in
Eurasia.
But the jawbone fits in with the emerging picture of earlier
out-of-Africa migrations that spread further into Eurasia than many had
believed. These pioneers appear to have lived alongside other human species
such as the Neanderthals and Denisovans. But it remains a mystery as to why
their genetic signatures are not preserved in people alive today.
The
field of ancient DNA - which involves extracting and analysing genetic material
from long-dead people - has provided us with unprecedented
insights into the past. One
striking result from 2018 was the discovery that the ancient people of Britain
were almost completely replaced in a
mass migration from the continent about 4,500 years ago.
The Neolithic
Britons had just erected the big stones at Stonehenge when they were overrun by
newcomers known as the Beaker people. This resulted in 90% of the British gene
pool being replaced in just a few hundred years. Why this happened is unknown.
But disease, famine and conflict are all potential candidates.
In a different
study released in 2018, researchers showed that 50,000-year-old bone fragments
from Russia belonged to girl who was half
Denisovan and half Neanderthal. The Denisovans and Neanderthals were
distinct species of human who inhabited Eurasia before our species - Homo sapiens - left Africa.”
Bron; BBC