1.5-Million-Year-Old Hominin Fossil Reveals Missing Link In Human Evolution

Conny Waters – MessageToEagle.com –  The ancient history of human evolution just got a bit more complicated, or perhaps the answers are there but scientists must still put together the jigsaw puzzle.

Researchers say a 1.5-million-year-old hominin fossil points to a previously unknown chapter in our history books and reveals a missing link in human evolution.

‘Ubeidya site locality. (a) Map of Africa and Eurasia with major Pleistocene paleoanthropological sites. Black circles denote sites with no osteological remains; red circles denote sites with human osteological remains. (b) The location of the site of ‘Ubeidiya, south of lake Kineret (Sea of Galilee), on the western banks of the Jordan Valley (red circle) (c) aerial photograph of the excavation plan of ‘Ubeidiya with the location of layer II-23 where UB 10749 was recovered.  Credit: Barash, A., Belmaker, M., Bastir, M. et al. – Nature

In 1966 scientists discovered ancient remains of a child that died near the Sea of Galilee. At the time no-one understood the significance of the find, but today it is obvious this was a finding of great archaeological and historical value.

Today scientists who examined the fossil unearthed at the early Pleistocene site of Ubeidiya know it is the earliest large-bodied hominin found in the Levant, and the second-oldest hominin fossil to be found outside Africa.

Archaic Humans Left Africa Several Times

The Levant hominin bone reveals there were multiple exits by archaic humans from Africa. The oldest hominin bone has been found in Dmanisi, Georgia, and has been dated 1.8 million years ago.

In a study published by Nature, scientists argue the difference of about 300,000 years offers evidence the Archaic child in the Jordan Valley and the hominins at Dmanisi were not the same species which implies there was more than one exit from Africa.

“Our analysis indicates that UB-10749 was a 6- to 12-year-old child at death, displaying delayed ossification pattern compared with modern humans.

Credit: Dr. Omry Barzilai – Israel Antiquities Authority

Its predicted adult size is comparable to other early Pleistocene large-bodied hominins from Africa. Paleobiological differences between UB 10749 and other early Eurasian hominins supports at least two distinct out-of-Africa dispersal events. This observation corresponds with variants of lithic traditions (Oldowan; Acheulian) as well as various ecological niches across early Pleistocene sites in Eurasia.

The Levant region, the major land bridge connecting Africa with Eurasia, was a significant dispersal route for Hominins and fauna during the early Pleistocene^. But while there are numerous Eurasian early Pleistocene sites, fossil hominin remains are rare,” the researchers write in their paper.

The Levant Hominin Fossil Changes The Story Of Human Evolution

Researchers believed previously that after the split from the Pan line (culminating in the chimpanzee) 7 million to 6 million years ago, human evolution was linear. Today they know this was not the case because there were multiple types of hominins, some living contemporaneously with one another and, as of 2 million years ago at least, roaming out of Africa.

“Clearly there was more than one hominin migration out of Africa. There could have been dozens, there could have been constant creep, in both directions – we simply don’t know. The fossil evidence of our prehistory is incredibly sparse and stone tools can only tell us so much.

We also can’t say how many hominin species there were in Africa when the ancestors of the Dmanisi crew exited. But among the earliest members of the Homo line in Africa was Homo habilis, which lived from perhaps 2.3 million to 1.6 million years ago. And following on its very heels, we find a new species – Homo erectus,” Dr. Alon Barash of the Azrieli Faculty of Medicine of Bar-Ilan University told the Haaretz.

Replica of Dmanisi Skull. Credit: Rama – Public Domain

Scientists have concluded the hominins from the Jordan Valley and Georgia were not of the same species, but the identity of the Dmanisi species is still a puzzle.

As Haaretz reports, “the Georgian authorities simply deflected any classification enigmas by dubbing their being Homo georgicus. Many simply assume it was a variant of erectus. But in fact they were small-bodied and had small brains, Barzilai points out.

Reconstruction of Homo georgicus showed them to be much shorter than erectus, he observes. Moreover, the stone tool culture found there is primitive Oldowan-type, not advanced Acheulean.

Yes, the team suspects that Dmanisi Person, aka Homo georgicus, arose from Homo habilis expanding out of Africa around 2 million years ago and reaching central Asia and perhaps beyond. Though while about it, Barash makes things even messier: there is no consensus that the creatures at Dmanisi belonged to a single species, he says.

UB 10749 vertebral body. (a) Superior view; (b) posterior view; (c) inferior view; (d) anterior view. Credit: Barash, A., Belmaker, M., Bastir, M. et al. – Nature

“The bottom line is that georgicus were definitely not Homo erectus,” he says. “For one thing, their brains were too small. If you took the Dmanisi skulls and put them in an African context, you would clearly see – it’s habilis.”

“Our conclusion that UB 10749 is a large-bodied Levantine hominin, supports the occurrence of several Pleistocene dispersals that were not only separated in time but also in ecology. Dmanisi is reconstructed as open grassland, with arid conditions compared to today.

In contrast, the younger site of Ubeidiya is reconstructed as warmer but more humid than Dmanisi, with closed woodland forests58. It follows that each of the hominin populations associated with the dispersals may have exhibited unique ecological and behavioral adaptations.

Most importantly, our interpretation that the large-bodied hominin from ‘Ubeidiya and the small-bodied hominin from Dmanisi were not from the same population explains the difficulty thus far in identifying a single early Pleistocene Homo niche,” the scientists write in their paper.

“When analyzing the early Pleistocene “Out of Africa” event, we should be cognizant that more than a single hominin population may have dispersed from Africa, each time with their own diverse biological and cultural adaptations,” the scientists explained.

Written by Conny Waters – MessageToEagle.com – AncientPages.com Staff Writer