Saturday, 28 August 2021

Evolution News - Another Ancient Hominin Species Identified by DNA.


The Leang Panninge (‘Bat Cave’) on the southern peninsula of Sulawesi, Indonesia.
© Leang Panninge Research Project
Oldest genome from Wallacea shows previously unknown ancient human relations | Max-Planck-Gesellschaft

More evidence is emerging that for much of our recent history, Homo sapiens existed alongside and interbred with several related species or subspecies or humans, behaving very much like a 'ring species' where a geographically widespread species is speciating into several related species and barriers to hybridization have not been fully established, allowing genes to flow between the species - something entirely predictable from the Theory of Evolution.

The fact that H. sapiens interbreed with H. neanderthalensis, the Denisovans (who have yet to be given a formal scientific name) and a third species known only from DNA fragments in our genome, is now very well established, as it the fact that H. neanderthalensis and the Denisovans also interbred. We also know of several other contemporaneous species with H. sapiens in the vicinity of this find, although there is no evidence of interbreeding with them - H. floresensis (the 'Hobbit') on the nearby Flores Island and H. luzonensis on the Island of Luzon in the Philippines. Palaeontologists have also discovered a so-far unnamed probable new species in Israel, the Ramala Homo, and from China, Homo longi sp. nov. ('Dragon Man'), both of which were contemporaneous with early H. sapiens, Neanderthals and Denisovans.

This confirmation of the TOE as it applies to H. sapiens is a constant irritant to Creationists, not simply because it confirms their most hated scientific theory, but also because it destroys their most cherished creation myth - the childish Bronze Age tale of a founding couple and 'original sin' and so the need for Jesus to 'save' us from the consequences of it. Not only does this interbreeding wreck the notion of a founding couple, but it wrecks the notion of even a founding species and of course totally destroys any notion of original sin and the need for salvation and a saviour! And without that superstitious fear with which to threaten their victims, where would the Abrahamic religions and their priests be?

a, Sulawesi and Wallacea. The red rectangle indicates the region shown in b. b, Leang Panninge. The dotted line indicates Toalean site distribution.
Now, as though to make matters worse for Creationists, scientists from the Max Planck Institutes for Evolutionary Anthropology (Leipzig) and the Science of Human History (Jena), the Senckenberg Centre for Human Evolution and Palaeoenvironment at the University of Tübingen, and Griffith University, Australia, have found evidence that H. sapiens interbred with a third species in South East Asia.

This evidence comes from the DNA recovered from the skull of a young female of the Toalean hunter-gatherer culture, which was restricted to this small part of Sulawesi, who was buried in the Leang Panninge more than 7,000 years ago. From the Max Planck Gesellschaft news release:
Selina Carlhoff, doctoral candidate at the Max Planck Institute for the Science of Human History and lead author of the study, isolated DNA from the petrous bone of the skull. “It was a major challenge, as the remains had been strongly degraded by the tropical climate,” she says. The analysis showed that the Leang Panninge individual was related to the first modern humans to spread to Oceania from Eurasia some 50,000 years ago. Like the genome of the indigenous inhabitants of New Guinea and Australia, the Leang Panninge individual’s genome contained traces of Denisovan DNA. The Denisovans are an extinct group of archaic humans known primarily from finds in Siberia and Tibet. “The fact that their genes are found in the hunter-gatherers of Leang Panninge supports our earlier hypothesis that the Denisovans occupied a far larger geographical area,” says Johannes Krause.

Another piece in the great genetic puzzle

Excavations at the Leang Panninge site: The skeleton as found.
© Hasanuddin University, Indonesia
A comparison with genomic data of hunter-gatherers who lived west of Wallacea at about the same time as the Leang Panninge individual provided further clues – that data showed no traces of Denisovan DNA. “The geographic distribution of Denisovans and modern humans may have overlapped in the Wallacea region. It may well be the key place where Denisova people and the ancestors of indigenous Australians and Papuans interbred,” says Cosimo Posth.

However, the Leang Panninge individual also carries a large proportion of its genome from an ancient Asian population. “That came as a surprise, because we do know of the spread of modern humans from eastern Asia into the Wallacea region – but that took place far later, around 3,500 years ago. That was long after this individual was alive,” Johannes Krause reports. Furthermore, the research team has found no evidence that the group Leang Panninge belonged to left descendants among today’s population in Wallacea. It remains unclear what happened to the Toalean culture and its people. “This new piece of the genetic puzzle from Leang Panninge illustrates above all just how little we know about the genetic history of modern humans in southeast Asia,” Posth says.
The team's open access paper was published in Nature a couple of days ago:
Abstract
Much remains unknown about the population history of early modern humans in southeast Asia, where the archaeological record is sparse and the tropical climate is inimical to the preservation of ancient human DNA1. So far, only two low-coverage pre-Neolithic human genomes have been sequenced from this region. Both are from mainland Hòabìnhian hunter-gatherer sites: Pha Faen in Laos, dated to 7939–7751 calibrated years before present (yr cal BP; present taken as AD 1950), and Gua Cha in Malaysia (4.4–4.2 kyr cal BP)1. Here we report, to our knowledge, the first ancient human genome from Wallacea, the oceanic island zone between the Sunda Shelf (comprising mainland southeast Asia and the continental islands of western Indonesia) and Pleistocene Sahul (Australia–New Guinea). We extracted DNA from the petrous bone of a young female hunter-gatherer buried 7.3–7.2 kyr cal BP at the limestone cave of Leang Panninge2 in South Sulawesi, Indonesia. Genetic analyses show that this pre-Neolithic forager, who is associated with the ‘Toalean’ technocomplex3,4, shares most genetic drift and morphological similarities with present-day Papuan and Indigenous Australian groups, yet represents a previously unknown divergent human lineage that branched off around the time of the split between these populations approximately 37,000 years ago5. We also describe Denisovan and deep Asian-related ancestries in the Leang Panninge genome, and infer their large-scale displacement from the region today.

What seems to be emerging from these and other finds is that an archaic hominin, probably H. erectus, migrated out of Africa into Eurasia and there diversified in partial isolation into several species and subspecies, including Neanderthals, Denisovans and a few others that we know about so far. But, maybe because the interbreeding was not very frequent, complete barriers to hybridization did not always evolve, so, wnen they did come into contact with one another and with the second wave of migration out of Africa by anatomically modern H. sapiens, also the descendants of African H. erectus, interbreeding was not only possible, but happened often enough for significant introgression of these ancient genes into the H. sapiens genome.
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