4 April 2020 | New Scientist | 37back as 320,000 years. Ring any bells?
Olorgesailie isn’t the only evidence
of earlier-than-expected technological
progress. The Jebel Irhoud fossils are
also associated with prepared core
tools. What’s more, Olorgesailie has
yielded up tools made of a glassy
volcanic rock called obsidian, which
doesn’t occur locally. The nearest
deposits are 25 kilometres away –
possible evidence of trade networks.
The site also reveals clear signs of
iron-rich rocks being processed into red
and black pigments, presumably for
artistic purposes, another indication of
behavioural and cultural sophistication.
It looks as though the transition to
modern cognition happened right at
the start of the H. sapiens journey, or
maybe even before it. So much for the
out-of-Africa mainstay, that humanity
became physically modern first, but
behavioural modernity didn’t evolve
until much later. “I think the two-step
model is dead,” says Foley.
From the stones and bones of Jebel
Irhoud, Olorgesailie and elsewhere,
a new and increasingly mainstream
view of human origins is emerging.
“African multiregionalism” doesn’t
completely overturn the incumbent
model. The continent is still the cradle
of humanity – although, as Foley points
out, “saying humans evolved in Africa
doesn’t mean very much, it’s a vast
area” – and humanity did disperse out
of Africa to eventually inhabit the entire
world. But the idea of a recent, localised
origin within a discrete population
has been buried. In its place is a much
deeper origin story beginning at least
300,000 years ago, and perhaps as
many as half a million years.
“If you’re looking for a big framework
in which to look at the evolution of
modern humans, it is the African
Middle Stone Age,” says Foley, referring
to the period from about 300,000
to 100,000 years ago. At the start of
this span, the whole continent of
Africa – possibly even “Greater Africa”,
which includes parts of the Middle
East – appears to have been dotted with
populations of archaic humans. These
were often isolated from one another
by geographical or ecological
boundaries such as deserts or jungles,
and mostly evolved independently,
although had sporadic contact andHOW DID HUMANITY
CONQUER EARTH?
One central pillar of the out-of-Africa
model of human origins is the “out”
part. This holds that about 60,000 years
ago, our species left Africa and, in an
epic sweep, filled Eurasia.
Cracks in that paradigm have been
growing for a long time. Human skulls
discovered at two sites in Israel, for
example, are 120,000 years old. These
are often seen as evidence that humanity
made some brief, failed, forays into
western Asia before the mass exodus.
But developments in the past few years
strongly suggest there was more to it. A
177,000 year-old jawbone from Misliya
cave in Israel, for instance, hints there
was a much older and longer-lasting
human presence in the Middle East.
A real jaw-dropper came last year,
when a pair of skulls discovered in
Greece in 1978 finally gave up their
secrets. They were recovered from
a coastal cave called Apidima, stuck
together back-to-back in a block of
volcanic breccia. Both were assumed
to be from Neanderthals and about
150,000 years old, but a reanalysis
showed otherwise. One was indeed
from a 170,000-year-old Neanderthal.
But the other was 210,000 years old
and from a Homo sapiens, albeit with a
mixture of modern and archaic features.
The skulls had somehow ended up in the
same part of the cave and became stuck
together some time later.
The only conclusion is that modern-ish
humans living in Africa more than
200,000 years ago successfully
dispersed into southern Europe, a long
trek by foot – or possibly raft – around
the eastern Mediterranean that probably
took millennia. “It’s very surprising,”
says Chris Stringer at the Natural History
Museum in London, who was part of the
team that did the analysis.
Evidence of early dispersals has been
found even further from Africa. In 2015,
researchers in China announced the
discovery of modern human teeth in
a cave in the south of the country that
dated to at least 80,000 years ago.
There are several other tantalising fossils
in China dating to about the same time,
too. These have conventionally been
classified as Homo erectus, the first
member of our genus, but it now seems
more likely that they are Homo sapiens,
says María Martinón-Torres at he
National Research Center of Human
Evolution (CENIEH) in Burgos, Spain.
“They were there!” she says. Stringer
agrees: “If they are in Europe than I don’t
see why they aren’t getting into China”.
These new discoveries of early
dispersals are intriguing, but the
big picture remains substantially
unchanged. The current thinking is
that modern humans migrated out of
Africa en masse some time after
100,000 years ago, probably via the
Arabian Peninsula or the Levant or both.
They gradually worked their way into
Europe and along the southern coast
of Eurasia, most likely in pursuit of
high-quality food resources, then “back
filled” into central Asia from what is now
China. Around 65,000 years ago some
people reached Sahul – an ancient
continent that is now Australia and New
Guinea – almost certainly by boat. The
last great migration then took humanity
across the Bering land bridge and into
the Americas around 15,000 years ago.Out of Africa, earlier
Until recently, the consensus was that Homo sapiens left
Africa around 60,000 years ago. Growing evidence
suggests that is wrongHomo
sapiens45,000
years ago
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