Did Early Humans First
Arise in Asia, Not Africa?
Two archaeologists are challenging what many experts consider
to be the basic assumption of human migration—that humankind arose
in Africa and spread over the globe from there.
The pair proposes an alternative explanation for human origins:
arising in and spreading out of Asia.
Robin Dennell, of the University of Sheffield in England, and
Wil Roebroeks, of Leiden University in the Netherlands, describe
their ideas in the December 22 issue of Nature.
They believe that early-human fossil discoveries over the past
ten years suggest very different conclusions about where humans,
or humanlike beings, first walked the Earth.
New Asian finds are significant, they say, especially the 1.75
million-year-old small-brained early-human fossils found in Dmanisi,
Georgia, and the 18,000-year-old "hobbit" fossils (Homo
floresiensis) discovered on the island of Flores in Indonesia.
Such finds suggest that Asia's earliest human ancestors may
be older by hundreds of thousands of years than previously believed,
the scientists say.
"What seems reasonably clear now," Dennell said, "is
that the earliest hominins in Asia did not need large brains or
bodies." These attributes are usually thought to be prerequisites
The authors maintain that, although there is no absolute proof,
putting all the evidence together requires an open mind about
other geographical origins of the first humans.
The First Asians?
The authors point out that there is very little solid information
about the first early humans in Asia, and paleontologists are
left with assumptions that are too often treated as historical
There is no archaeological or fossil evidence to prove that
early humans moved from southern Africa to the Nile Valley in
the early Pleistocene (1.8 million years ago to 11,500 years ago),
The earliest evidence of a human ancestor in Asia appears to
be the 1.8-million-year-old cranium found in Mojokerto, Indonesia.
But, the authors note, the fact that no older specimens have been
found in Asia does not prove that they didn't exist.
Dennell and Roebroeks get support for their proposal from other
"I think this is an interesting and constructively provocative
paper," said Chris Stringer, a researcher in the department
of palaeontology at London's Natural History Museum.
"Evidence of humans in the Caucasus [region of Asia],
China, and Java more than 1.6 million years ago implies either
a very rapid spread from Africa after about 1.8 millions years
ago, or that such populations were established outside Africa
earlier than present evidence suggests," he said.
"I certainly think we should keep an open mind about the
The earliest tools found in Asia are routinely attributed to
Homo erectus, a species known to have come from Africa.
H. ergaster—an African species that many experts believe gave
rise to H. erectus—is assumed to have been the only primate capable
of migrating out of Africa.
Experts cite its body form—long limbs, humanlike proportions,
and a brain capable of figuring out how to hunt for meat—as evidence
that it was the only species suited to life in prehistoric Asian
This might be a persuasive argument—except for the fact that
australopithecines, an older form of humanlike primates, had colonized
the African savannah by 3.5 million years ago.
Similar grasslands extended across Asia at the time, suggesting
that australopithecines could have survived quite well in the
region, the authors say.
What's more, fossil evidence for H. ergaster in Asia in the
early Pleistocene is weak.
No one yet knows where H. floresiensis first came from, but
it may turn out that the diminutive species has its origins in
Stringer, of the Natural History Museum, sees this as a possibility.
"The unresolved status of the intriguing Flores finds attributed
to H. floresiensis leaves open the possibility that this species
is the end result and last survivor of an ancient migration of
very primitive humans, or even prehumans, that formerly existed
more widely across Asia."
So when did early humans first leave Africa? Could they have
left as early as 2.6 million years ago, as soon as they started
making stone tools?
"Hominins could easily have left Africa two million years
ago," Dennell said. "After all, they certainly didn't
need big brains or bodies to do so."
Maybe, he concluded, "the Dmanisi [Georgia] hominins are
an extremely primitive version of H. erectus that is the ancestor
of the H. erectus populations in both Java and those in East Africa.
"In other words, we might be looking at [human migration]
'out of Asia,' and not 'out of Africa.'"