Monday, August 6, 2018

The Genetics Of The Modern Pygmy Population Of Flores

The island of Flores, which is the source of archaic hominin remains for a species colloquially known as "Hobbits" also has a modern pygmy population that is about half a meter taller than the hobbits who live in Rampasasa, Flores, Indonesia, which is right next to the Liang Bua cave where Homo floresiensis remains were found.

Analysis of their genomes reveals that they cluster genetically with the Lebbo people of Borneo, previously discussed at this blog, who are a mix of Southeast Asian ancestry and Papuan ancestry, and the Mamanwa of the Philippines. The pygmies of Flores have Denisovan ancestry proportionate only to their Papuan ancestry, with no signs of enhanced Denisovan ancestry from additional Flores based gene flow.

5 comments:

neo said...

btw do u have a theory on the hobbit?

my theory is that the hobbit is a branch of a hitherto unknown branch of asian Australopithecus

quite possibly Australopithecus and even human origins started in asia, and one lineage then spread to Africa, rather than reverse



DDeden said...

BBC
Hobbits not AMHs Pygmies

"The new analysis showed that the Flores pygmies are not significantly distinct, genetically-speaking, from other populations around the world. Like some other humans in the same region, the pygmies have inherited part of their DNA code from both Neanderthals and another type of early human, the Denisovans.

The scientists also found that the modern pygmies have a high occurrence of gene variants that are associated with reduced height and plant-based diets."

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The last sentence is flawed, both the Flores hobbits (Homo habilis) and the modern AMHs Pygmoid people of Rampassasa village nearby the cave have the normal height of tropical rainforest people, neither had "reduced height".

DDeden said...

The brain size of the hobbits was unusually small, but within the range of female Hh, not female AMHs female Pygmies.

andrew said...

@neo

"do u have a theory on the hobbit?"

My working hypothesis is that they are hominins more archaic than H. Erectus, although probably genus Homo rather than Australopithecus.

"quite possibly Australopithecus and even human origins started in asia, and one lineage then spread to Africa, rather than reverse"

Almost certainly not.

@DDeden

I think you are quoted the linked material, but haven't gone back and checked. (Keep in mind that the original is in French so the translation may not be perfect).

"both the Flores hobbits (Homo habilis) and the modern AMHs Pygmoid people of Rampassasa village nearby the cave have the normal height of tropical rainforest people, neither had "reduced height""

While plausible, I would not definitively categorize Flores hobbits as Homo habilis, it is something of an open question, although more plausible than the Australopithecus hypothesis of @neo.

The Flores hobbits at ca. 1.02 meters in average height and the modern AMHs Pygmoid people of Rampassasa village at ca. 1.48 meters of average height, can't both be "normal height of tropical rainforest people" even if one of them were. The statement that they have "reduced height" is implicitly relative to other modern humans in the case of AMH Pygmies, and that certainly is true, even if other tropical rainforest people naturally tend to evolve towards reduced height as well.

Since we can't be sure what the Flores hobbits evolved from, it is harder to know if they are of "reduced height" relative to non-island, non-tropical forest dwelling hominins of their species and the thinness of the archaic hominin fossil record doesn't help on that score.

"The brain size of the hobbits was unusually small, but within the range of female Hh,"

True.

"not female AMHs female Pygmies."

This is a bit garbled, but I'd agree that hobbits had brain sized below the range of any group of adult AMHs in existence today.

andrew said...

An earlier post at this blog explores the quite plausible H. Habilis theory and also provides some data on the height of that species: http://dispatchesfromturtleisland.blogspot.com/2017/08/the-neanderthal-denisovan-branch-of.html

'there are fairly strong indications that Homo floresiensis may actually have been either a different more primitive hominin species than Homo erectus, perhaps a close relation of Homo habilis who evolved ca. 2,400,000 years ago (about 400,000 years before Homo erectus, but overlapping with it for about 600,000 years in Africa) and is the oldest definitively identified member of the genus Homo.

Homo habilis was more adapted for a life in the trees (as opposed to walking longer distances on the ground) than Homo erectus, used more primitive stone tools than Homo erectus, and while also an omnivorous meat eater had a diet that was more plant heavy and lighter on meat than Homo erectus who ate "some tougher foods like leaves, woody plants, and some animal tissues, but that they did not routinely consume or specialize in eating hard foods like brittle nuts or seeds, dried meat, or very hard tubers." Homo erectus used fire (although it isn't clear just how much mastery they had over it) while Homo habilis did not - which would have encouraged Homo habilis to live in places not easily razed by intentionally set forest and brush fires (a key tool used by Australian Aborigines to defeat impressive Australian megafauna).

Homo habilis averaged 3 foot 4 inches to 4 foot 5 inches and averaged about 70 pounds, consistent with Homo floresiensis which averaged about 3 foot 6 inches. In contrast, Homo erectus had body proportions similar to modern humans an averaged 4 foot 9 inches to 6 foot 1 inch, and averaged about 88-150 pounds.

So, it is possible to image that Homo erectus and Homo habilis could have co-existed in different ecological niches in Asia, with Homo habilis favoring dense Asian jungles, while Homo erectus favored lightly wooded area and other more open spaces similar to the African savannah which may have been favored by their ancestors.

Homo floresiensis or its ancestors, could have been a fellow traveler with Homo erectus or Homo heidelbergensis, or may have arrived in a separate Out of Africa migration of its own.

Oldowan stone tools, normally associated with Homo habilis in Africa, are found in Asia from very ancient times until about 200,000 to 300,000 years ago."