4 April 2020 | New Scientist | 35“ New fossils, tools
and analyses of
genomes have thrown
everything into disarray”
California, Berkeley, sequenced 147
mitochondrial genomes from living
people around the world. The
mitochondria in cells are inherited
from mothers only, and the study
indicated that everyone was descended
from a single woman – dubbed
“mitochondrial Eve” – who probably
lived in Africa about 200,000 years ago
(see “How does DNA analysis reveal our
prehistory?”, page 41).
The result was very influential, says
Foley. It was quickly consolidated into
what he calls the “recent out-of-Africa
package”, the idea that modern humans
appeared quite abruptly in eastern or
southern Africa some time between
150,000 and 200,000 years ago and
went on to conquer the world. The
package also introduced the distinction
between anatomical and behavioural
modernity. Based on archaeological
evidence, it looked as though early
Homo sapiens had bodies like us but
weren’t as advanced mentally. Only
later, about 50,000 or 60,000 years ago,
did the full package evolve – perhaps
due to a chance mutation – making
dispersal out of Africa possible. This
neat, compelling narrative became
known as “the human revolution”.
For a while, the fossil evidence
obligingly supported this story.
Although remains from the crucial time
of about 150,000 years ago were absent,
there were several older human skulls
that seemed to fit the idea.
One of the most distinct features
of modern humans is the shape of
our heads. Compared with our extinct
ancestors, we have small, flat, delicate
faces, prominent chins and spherical
brain cases. A skull with all or most
of these features will generally be
classified as belonging to our species.
Two of the oldest-known complete
skulls with hints of this anatomy
were discovered by Richard Leakey and
his team at Omo-Kibish in southern
Ethiopia in 1967. Known as Omo I
and Omo II, they are now dated to
about 200,000 years old and have
a mixture of archaic and modern
features – exactly what you would
expect of an archaic African
human shortly before the evolution
of anatomical modernity. Several other
specimens from around eastern and
southern Africa told a similar story. >