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2 Posts tagged with the chris_stringer tag
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Finds from Taiwan and Israel shed light – and confusion – on the story of ancient human species.

Find 1: A mysterious jawbone from Penghu, Taiwan

Discovered by chance by fishermen off the coast of Taiwan, an unusually thick and primitive human jawbone shows a challenging mix of features. While no DNA has yet been recovered from the specimen, its characteristics make it difficult to classify into existing groups.

 

The jawbone is short and wide, with a thick body and large teeth. It dates within the last 450,000 years, and most likely within the last 200,000.

Jawbone-Split_3179032b.jpg

The jawbone, left, and a reconstruction of the jaw, right © Yousuke Kaifu.

 

A partial Homo erectus skull from the Chinese mainland has some large associated teeth and could be 400,000 years old, so the new jawbone may belong to the same group. But it could also be one of the elusive ‘Denisovans’, a group known only by DNA from a fragmentary fossil finger bone and two very large molar teeth in a Siberian cave.

 

Museum human origins expert Prof Chris Stringer said this could be an interesting development:

I have considered the Denisovans as an Asian sister group of the Neanderthals, and like them, derived from Homo heidelbergensis, but if Penghu is indeed a long-awaited Denisovan jawbone, it looks more primitive than I would have expected.

He said of the find:

As the authors note, this enigmatic fossil is difficult to classify, but it highlights the growing and not unexpected evidence of human diversity in the Far East, with the apparent co-existence of different lineages in the region prior to, and perhaps even contemporary with, the arrival of modern humans some 55,000 years ago.

Read the original paper

 

Find 2: The skull of a possible early migrant, from northern Israel

A later and much better-dated specimen, the partial skull of an early modern human from Manot Cave dates to a time of migration out of Africa and interbreeding with Neanderthals. At about 55,000 years old, it sits comfortably in the timeframe estimated for early modern human and Neanderthal interbreeding, 50-60,000 years ago.

 

The skull itself has characteristics indicative of early modern humans, and without DNA it is impossible to say yet whether interbreeding with Neanderthals had an impact on the individual. Nonetheless, Prof Stringer said it is a critical find for examining possible migrant populations:

Manot might represent some of the elusive first migrants in the hypothesised out-of-Africa event about 60,000 years ago, a population whose descendants ultimately spread right across Asia, and also into Europe. Its discovery raises hopes of more complete specimens from this critical region and time period.

Read the original paper

 

Related human origins posts:

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A group of bones discovered ten years ago in Indonesia were determined to be a new human species that lived about 17,000 years ago. The only skull, with very small proportions, earned the species the ‘hobbit’ nickname.

 

Now, a new paper suggests that the hobbit is just an individual with Down syndrome, but Museum human origins expert Prof Chris Stringer doubts the conclusions.

 

The find, on the island of Flores, included bones from several individuals, but only one had a complete skull and leg bones, from which the original calculations of height and brain capacity were made.

 

Standing at approximately 1.06m (3.5ft) tall and with a brain only a third of the size of modern humans, the bones seemed to belong to a new species, which was named Homo floresiensis.

 

homo_floresiensis.JPG

A copy of the Homo floresiensis skull.
Credit: Ghedoghedo, Wikimedia Creative Commons.

 

A new analysis of the skull and thigh bones, published this week in a paper in the journal Proceedings of the National Academy of Sciences USA (PNAS), suggests that these estimates are too low, and a slightly bigger individual actually lies within the range of modern humans with Down syndrome.

 

The authors support their claims with other evidence, including the asymmetry of the skull, a condition common in modern individuals with Down syndrome. They conclude this one individual had a developmental disorder, and all the remains were in fact modern humans.

 

Still a new species?

 

However, Prof Stringer is sceptical of the conclusions. Although there are no other complete skulls, there is another jaw that has similar proportions and characteristics.

 

Both appear to have no chin, instead showing internal bony reinforcements similar to those found in prehuman fossils from at least two million years ago. This feature is not found in Down syndrome. The wrist bones of two individuals also show features previously unknown in humans from the last one million years, further indicating a unique species.

 

Weight of evidence

 

New human species are often difficult for the scientific community to accept, especially from so few bones. Prof Stringer, however, sees parallels between the stories of H. floresiensis and the Neanderthals, originally described from a single site:

A number of pathological conditions were advanced to explain away the distinctive morphology of the Neander Valley skeleton, but other finds gradually forced the acceptance of the Neanderthals as a distinct and extinct human group.

Prof Stringer acknowledges that more H. floresiensis individuals are needed to establish the range of sizes and shapes there may have been, but he thinks this new analysis does not shake the foundations of the species:

In my view this paper does not provide a sound basis to challenge the basic conclusion that a primitive human-like species persisted on the island of Flores within the last 100,000 years.