36 | New Scientist | 4 April 2019
It got even better when, in 1997,
palaeontologists in Ethiopia’s Afar
depression unearthed three human
skulls, two adults and a juvenile. The
so-called Herto hominins are between
154,000 and 160,000 years old, and also
have a mixture of archaic and modern
facial and cranial features. They were
found associated with tools that had
elements of both old and new Stone
Age technology. The hominins’ age,
location and toolkit were neatly in tune
with the recent out-of-Africa model and
convinced the researchers that they were
the “probable immediate ancestors of
anatomically modern humans”.
Done and dusted, you might think.
But that turned out to be the high-water
mark. Discoveries since then have been
difficult, if not impossible, to slot into
this neat little box. And the Jebel Irhoud
fossils have done more than almost
anything else to upend the old order.
Back in 1961, archaeologists noted
that the skull had modern facial
features – a flat and delicate face, and
a prominent chin – together with an
archaic, elongated braincase. When
dating put it at around 40,000 years
old, it was classified as maybe belonging
to an African Neanderthal or a relic
population of some other archaic
hominin, and shunted to the margins
of the story. But doubts about the
dating persisted and, in 2004, a team
led by Jean-Jacques Hublin of the
Max Planck Institute for Evolutionary
Anthropology in Germany reopened
the site. The researchers hoped to get a
more accurate date – which they did –
but they also got more fossils, including
another near-complete skull. It too had
a modern face and ancient braincase.
When the date came back, it was
astounding: 315,000 years old, plus or
minus 34,000 years (see “How to tell
the age of a fossil”, page 40).
This was a serious challenge to the
out-of-Africa idea. Anatomically, the
skull is at least as modern as those
found at Herto, which are considered
to be right on the cusp of modern
humanity. “It is a creature which is very
nearly a modern human, anatomically,”
says Foley. And yet it lived at least
130,000 years before H. sapiens was
meant to have evolved, at a time when
our direct ancestors were still banging
rocks together in eastern or southernAfrica. It was also on the fringes of the
continent, thousands of kilometres
from the supposed cradle of humanity.
When the new Jebel Irhoud dates
were revealed in 2017, they inspired a
major rethink of other fossil skulls from
around the same time. It turned out
that these told a similar story. The
Florisbad specimen from South Africa,
for example, is about 260,000 years old,
yet has a surprisingly modern face.
Ditto some skulls from Laetoli in
Tanzania and two locations in Kenya,
Guomde and Eliye Springs. All possessTOP:^ THE
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IENTIFIC^ FILMSUntil recently
the Jebel Irhoud
skull (above) was
thought to belong
to a Neanderthal,
and the Sima
hominins (below)
were classified
as Homo
heidelbergensisa mosaic of modern and archaic
features – but, oddly, are also very
different from one another.
Another old site with a new story
to tell is Olorgesailie in Kenya.
Originally excavated in the mid-1980s,
Olorgesailie is an ancient lake bed,
known for stones rather than bones,
specifically an abundance of prehistoric
tools. It captures a crucial changing
of the guard from one tool-making
culture – the Acheulian, with large, crude
hand axes – to a more sophisticated
one. The site is characterised by a finer
and more varied toolkit based on
something called the “prepared core”:
a block of flint or chert worked in such
a way that smaller blades and points
can be struck from it with a single blow.Tooling up
Making such a core requires a high level
of abstract thought and planning, and
so is regarded as a product of modern
minds. The Acheulian toolkit, on the
other hand, is definitely pre-H. sapiens.
It was invented by our distant ancestor
H. erectus around 1.2 million years ago.
The transition to the prepared core
technology was once thought to have
been relatively recent, in keeping with
the human revolution model, but new
dating from Olorgesailie says otherwise.
The transition there happened at least
305,000 years ago, and maybe as far