4 April 2020 | New Scientist | 39interbreeding, perhaps when climatic
conditions changed and boundaries
shifted. This fluid situation persisted for
150,000 years or more, and left behind
those now-familiar mosaic skulls.
Genetic studies point in the same
direction, says Carina Schlebusch at
Uppsala University in Sweden. She and
her colleagues analysed a collection of
contemporary genomes from all over
Africa attempting to home in on the
origin of H. sapiens. “It did not point
to any one particular place,” she says.
“It pointed to south Africa, east Africa
and west Africa. Basically, it pointed to
every place where we had samples from.
As I understand it, the transition fromOmo I human
200,000 years old
Shows a mix of archaic
and modern featuresHerto human
160,000 years old
Archaic/modern mix,
but distinct from Omo ILaetoli human
120,000 years old
More modern but more
archaic-lookingContemporary human
Looks most like
Florisbad humanstoked debates about which belong
to our species and which don’t. Some
fossils are widely accepted as being
H. sapiens, notably Omo I and the
Herto hominins (although they are
substantially different from one
another, and some prefer to categorise
the latter as a subspecies). The Jebel
Irhoud fossils divide opinion, with
some palaeoanthropologists happy to
accept them into the immediate family
but others not. The rejects are generally
categorised, rather vaguely, as “African
archaics”, which is essentially dodging
the issue. Some of these might be
separate species. It has been proposed,
for example, that the Florisbad fossils
be categorised as Homo helmei –
however new findings appear to be
undermining this idea, as we shall see.
Maybe this is all moot, anyway,
hung up on an increasingly outdated
concept of what constitutes a species.
It is commonly taken to be a group of
organisms that can interbreed. But this
“biological species” concept is just one
of dozens of competing definitions.
Some are based on shared ancestry,
others on shared behaviour, genes or
anatomy. As Stringer points out, the
biological species concept doesn’t
hold up for many living species of
mammals. Coyotes and grey wolves,
for example, can interbreed to
produce a third “species”, the red wolf.
Why not humans too? In this emerging
view, early H. sapiens is less a species
than a clade: a group of organisms
of various taxonomic groups,
descended from a common ancestor
and sharing many features, but also
with a lot of physical variation.315,000 years ago
Newest estimate of the origin
date of Homo sapiensarchaic to modern happened in
different parts of the African continent.”
African multiregionalism represents
a major shift in thinking. There was no
single ancestral population, but many,
spread over a huge area, which merged
and split and merged again like a
braided stream, evolving at different
rates and in distinct directions in
different places. The suite of anatomical
and behavioural features that define
modern humanity didn’t appear as one
complete package, but gradually
coalesced across vast tracts of space and
time. “There was never a single centre of
origin,” says Chris Stringer at the Natural
History Museum in London. We are a
“composite”, he says. “I think it is a really,
really important and profound idea,”
says Richard Potts at the Smithsonian
Institution in Washington DC, who
led the Olorgesailie excavations.
The anatomical diversity of these
composite humans has inevitablyAlong with
the oldest
known human
remains, Jebel
Irhoud in
Morocco has
yielded many
sophisticated
stone toolsMO
HA
MM
ED
KA
MA
L/M
PI^
EVA
LE
IPZ
IG/
UP
I/A
LA
MY
SHANNON^ MCP
HERR
ON,^ MPI^ EVA^LEIPZ
IG,
LICENSE:CC- B
Y-S
A^2.^0
LEFT TO RIGHT: MARKUS SCHIEDER/ALAMY; PHAS/GETTY IMAGES;
NATURAL HISTORY MUSEUM LONDON/ALAMY; SMITHSONIAN’S HUMAN
ORIGINS PROGRAM; NATURAL HISTORY MUSEUM LONDON/ALAMY;
AGEPHOTSTOCK/ALAMY; NATURAL HISTORY MUSEUM LONDON/SPL;
SABENA JANE BLACKBIRD/ALAMY>1cm