Homo Erectus Origins in Eurasia, Not Africa?

Homo erectus models from Kenya National Museum.

Scientists are questioning the long-held belief that early humans migrated solely from Africa. An even earlier group of Homo erectus may have migrated instead from Eurasia to Africa.

Much of the new speculation regarding humans’ earliest migrations comes from Dmanisi, a major archaeological site in the mountains in the Republic of Georgia, between Europe and Asia. Evidence now points to human occupation there some 1.85 million years ago, substantially earlier than previously believed.

"The recently discovered data show that Dmanisi was occupied at the same time as ~ if not before ~ the first appearance of Homo erectus in east Africa," team leader Reid Ferring of the University of North Texas tells the Associated Press. "We do not know as yet what the first occupants looked like, but the implication is that they were similar to, or possibly even more primitive than those represented by Dmanisi's fossils."

The occupants of Dmanisi "are the first representatives of our own genus outside Africa, and they represent the most primitive population of the species Homo erectus known to date," according to David Lordkipanidze of the Georgia National Museum. The early humans at Dmanisi "might be ancestral to all later H. erectus populations, which would suggest a Eurasian origin of H. erectus."

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Homo Sapiens' Journey to Modern Human

Scholarly debate surrounds when “archaic Homo sapiens” emerged as the modern version of humans. American Scientist recently explored the topic in an article, “Refuting a Myth About Human Origins” by John J. Shea, professor of anthropology at Stony Brook University and a research associate with the Turkana Basin Institute in Kenya.

In Europe, the oldest Homo sapiens fossils date to only 35,000 years ago. But studies of genetic variation among living humans suggest that our species emerged in Africa as long as 200,000 years ago. Scientists have recovered Homo sapiens fossils in contexts dating to 165,000 to 195,000 years ago in Ethiopia’s Lower Omo Valley and Middle Awash Valley. Evidence is clear that early humans dispersed out of Africa to southern Asia before 40,000 years ago. Similar modern-looking human fossils found in the Skhul and Qafzeh caves in Israel date to 80,000 to 120,000 years ago. Homo sapiens fossils dating to 100,000 years ago have been recovered from Zhiren Cave in China. In Australia, evidence for a human presence dates to at least 42,000 years ago. Nothing like a human revolution precedes Homo sapiens’ first appearances in any of these regions. And all these Homo sapiens fossils were found with either Lower or Middle Paleolithic stone tool industries.

Shea delineates the various findings and frequently references his own take on the situation, as in:

For me, the most surprising aspect about the debate regarding when Homo sapiens became human is that archaeologists have not tested the core hypothesis that there were significant behavioral differences between the earliest and more recent members of our species. Because modernity is a typological category, it is not easy to test this hypothesis. One is either behaviorally modern or not. And, not all groups classified as behaviorally modern have left clear and unambiguous evidence for that modernity at all times and in all contexts. For example, expedient and opportunistic flintknapping of river pebbles and cobbles by living humans often creates stone tools indistinguishable from the pebble tools knapped by Homo habilis or Homo erectus. This similarity reflects the nature of the tool-making strategies, techniques and raw materials, not the evolutionary equivalence of the toolmakers. Thus, the archaeological record abounds in possibilities of false-negative findings about prehistoric human behavioral modernity.

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Analysis Puts Homo Erectus Earlier

Cranial reconstruction of Java Man, aka Homo erectus.

After convincing colleagues that Homo erectus may have persisted on the Indonesian island of Java as recently as 30,000 years ago ~ recent enough to have coexisted with modern humans for more than 100,000 years ~ anthropologists last week presented new analyses suggesting the fossils may predate Homo sapiens by hundreds of thousands of years.

“It’s confusing right now, but I suspect that Homo erectus’ age on Java is still relatively young,” said Christopher Stringer of London’s Natural History Museum. A new analysis of sediment on Java suggests that animal fossils on the island date to between 200,000 and 150,000 years ago, providing a possible framework for when H. erectus lived there, he added.

According to Science News:

It all depends which radiometric method you use to assess the fossils’ age, New York University anthropologist Susan Antón reported at the annual meeting of the American Association of Physical Anthropologists.

Antón and an Indonesian colleague lead a team that first announced in 1996 that sediment at two H. erectus sites on Java dates to between 50,000 and 30,000 years ago. Those “remarkably young” dates, based on analyses of radioactive elements in fossil-bearing sediment, suggest that H. erectus survived well into the era dominated by modern humans, Antón said. Many researchers now accept those dates.

New analysis ~ based on measurements of radioactive argon’s decay in volcanic rock above and below the fossils ~ puts H. erectus’ age on Java at roughly 550,000 years. It’s not clear why these estimates differ so dramatically and which one is more accurate, Antón said.

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Face of Earliest European is Reconstructed

At the behest of the BBC, a skilled forensic artist has reconstructed the head and facial features representing the first anatomically modern human to live in Europe ~ a person inhabiting the Carpathian Mountains of Romania about 35,000 years ago.

According to Britain's The Independent:

The artist's reconstruction ~ a face that could be male or female ~ is based on the partial skull and jawbone found in a cave where bears were known to hibernate. The facial features indicate the close affinity of these early Europeans to their immediate African ancestors, although it was still not possible to determine the person's sex.

The lower jawbone of the first modern European was discovered in 2002 in Pestera cu Oase, the "cave with bones", located in the southwestern Carpathians. The remaining fragments of skull were unearthed in 2003.

Scientists have dated the bones using radiocarbon analysis to between 34,000 and 36,000 years ago when Europe was occupied by both Neanderthal man, who had lived in the region for tens of thousands of years, and anatomically-modern humans – Homo sapiens – who had recently arrived on a migratory route from Africa via the Middle East.

Although the skull shares many modern feature of human anatomy, it also displays more archaic traits, such as very large molar teeth, which led some scientists to speculate the skull may belong to a hybrid between Homo sapiens and Neanderthals ~ an idea discounted by other experts.

The reconstruction was made for the forthcoming BBC 2 series The Incredible Human Journey, which documents human origins and evolution.

Click here for the complete The Independent article.

Peking Man Now Believed 750,000 Years Old

Homo erectus skull from the Zhoukoudian caves.

A new and more accurate dating method shows Peking Man may be 200,000 years older than previously thought. Bones of Sinanthropus pekinensis ~ a Homo erectus commonly known as Peking Man ~ were discovered in the 1920s during cave excavations near Beijing and now believed to be 750,000 years old.

Scientists have used various techniques to try and date the fossils, but a lack of suitable methods for cave deposits has limited their accuracy. Shen and his colleagues used a relatively new method that examines the radioactive decay of aluminum and beryllium in quartz grains, which enabled them to get a more precise age for the fossils.

"The analysis dated the finds to around 750,000 years old, some 200,000 years older than previous estimates and indicates a hominin presence in the area through glacial and interglacial cycles. The results should help to build a more reliable chronology of human evolution in East Asia," the researchers wrote.

Click here for the Reuters article.
Click here for a more extensive LiveScience article.