Oldest Homo sapiens found to date?


#1

https://www.nature.com/news/oldest-homo-sapiens-fossil-claim-rewrites-our-species-history-1.22114

This article discusses fossils recovered from Jebel Irhoud cave in Morocco. The group of fossils from 5 different individuals included a partial skull and lower jaw.

Does anyone know if there is consensus on whether these should be classified as highly evolved H. heidelbergensis or early H. sapiens?

(Skull is elongated in comparison to modern human skull on right)


(Stephen Matheson) #2

Apparently not. From a Perspective piece in Science a few months ago:

The apparently prolonged evolution of H. sapiens has raised questions about the extent of anatomical modernity that is necessary or sufficient for classifications of early H. sapiens . This has led to suggestions that ancient hominin populations in China (represented by the Dali fossil, which is roughly contemporaneous with those from Jebel Irhoud) could have been involved in modern human origins. If this is the case, it challenges the exclusivity of Africa in the evolution of the derived traits of H. sapiens , providing support for multiregionalism. However, resemblances between the Dali and Jebel Irhoud crania seem to be mainly based on primitive retentions rather than evolutionary novelties. The supposedly derived facial shape of early members of H. sapiens , such as those at Jebel Irhoud, may actually be more ancient, possibly tracing back to the common ancestor with Neandertals ( 5 ) (see the figure).


(Jay Johnson) #3

Would you mind emailing a PDF of that one to me?

On @jasonbourne4’s PO, my impression is that the majority of paleoanthropologists accept the classification of Jebel Irhoud as sapiens, but how much of a majority is needed to declare a “consensus” on the question? That, I can’t say.

Part of the problem, which Stephen pointed out in the excerpt, is deciding how many modern anatomical features are necessary in order to classify a fossil as sapiens. (Someone lost the checklist that came with the owner’s manual.) The question of facial shape concerns the fact that all previous hominins have an elongated skull and a large face, while sapiens have a globular brain case and a small face. The archaic sapiens at Jebel Irhoud has our face, but not our brain case. The Dali skull from China has a strange mix of features, a few of them modern, which again makes it difficult to classify.

People often think of evolution as a straight-line process in which one species is directly replaced by the next, but that’s not the case. By 1.8 million years ago, just 100,000 years after Homo erectus appeared, three different species of hominin and A. sediba were co-existing in East Africa, as well as the smaller-bodied H. erectus in Dmanisi, Georgia, and probably H. naledi in South Africa. Considering the mosaic of bodily features present at the time, anthropologist Susan Anton calls the phase leading to the appearance of erectus a period of “morphological experimentation” in the size and shape of the body. With later erectus, the general outlines of the present human body have taken shape.

Of course, none of that was apparent until recent fossil finds made it apparent. As more discoveries are made, I believe we will see a similar pattern of “morphological experimentation” emerge in the fossil record between ~400-200 Kya, but this time it involves the head and brain, not the body. So far, we only have Jebel Irhoud and Dali as examples, but I’m sure there will be more. The difficulty is that we are talking about a fairly short time frame, so coming across a hominin fossil of just the right age is mostly blind luck.


#4

Agreed. We shouldn’t be surprised to find it increasingly difficult to distinguish our species with others as more and more fossils are discovered, especially as species often overlap chronologically. I pose the question just to try to stay up-to-date with current paleoanthropologic consensus when speaking of the age of our species.


(Jay Johnson) #5

You work too hard, brother.


#6

Even in this scenario you will still have to decide on an arbitrary point between H. sapiens and not H. sapiens on that straight line. When it comes to assigning names to fossil species it is often arbitrary, and necessarily so. At least with living sexual species we can use more objective criteria like gene pools.


(system) #7

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