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View Full Version : Genetic evidence for Early Modern Human Presence in Sumatra 73-63000 years ago



Angela
10-08-17, 04:57
See:
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html?WT.ec_id=NATURE-20170810&spMailingID=54671564&spUserID=MjA1NzU5OTE5NwS2&spJobID=1221417065&spReportId=MTIyMTQxNzA2NQS2&foxtrotcallback=true

"Genetic evidence for anatomically modern humans (AMH) out of Africa before 75 thousand years ago (ka)1 (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html#ref1) and in island southeast Asia (ISEA) before 60 ka (93–61 ka)2 (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html#ref2) predates accepted archaeological records of occupation in the region3 (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html#ref3). Claims that AMH arrived in ISEA before 60 ka (ref. 4 (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html#ref4)) have been supported only by equivocal5 (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html#ref5) or non-skeletal evidence6 (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html#ref6). AMH evidence from this period is rare and lacks robust chronologies owing to a lack of direct dating applications7 (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html#ref7), poor preservation and/or excavation strategies8 (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html#ref8) and questionable taxonomic identifications9 (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html#ref9). Lida Ajer is a Sumatran Pleistocene cave with a rich rainforest fauna associated with fossil human teeth7 (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html#ref7), 10 (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html#ref10). The importance of the site is unclear owing to unsupported taxonomic identification of these fossils and uncertainties regarding the age of the deposit, therefore it is rarely considered in models of human dispersal. Here we reinvestigate Lida Ajer to identify the teeth confidently and establish a robust chronology using an integrated dating approach. Using enamel–dentine junction morphology, enamel thickness and comparative morphology, we show that the teeth are unequivocally AMH. Luminescence and uranium-series techniques applied to bone-bearing sediments and speleothems, and coupled uranium-series and electron spin resonance dating of mammalian teeth, place modern humans in Sumatra between 73 and 63 ka. This age is consistent with biostratigraphic estimations7 (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html#ref7), palaeoclimate and sea-level reconstructions, and genetic evidence for a pre-60 ka arrival of AMH into ISEA2 (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23452.html#ref2). Lida Ajer represents, to our knowledge, the earliest evidence of rainforest occupation by AMH, and underscores the importance of reassessing the timing and environmental context of the dispersal of modern humans out of Africa."

I guess we'll see how this is received.

bicicleur
10-08-17, 08:10
there was a 1st wave of AMH into SE Asia that got extinct and that predated the 2nd wave of our forebears

Fire Haired14
10-08-17, 08:21
If you go strictly by mtDNA/Y DNA age estimates the ancestors of Eurasians left Africa roughly 70,000 years ago. Now what does 'Left Africa' really mean? It means 70,000ky is the most recent mtDNA/Y DNA connection between Sub Saharan Africans and Eurasians. For all we know the ancestors of Eurasians and Sub Saharan Africans were living in Arabia in 70,000 years ago. There's no way to know if they were really living in Africa back then.

And btw North Africa should be considered apart of Eurasia genetically. When people say 'Africa' they're usually just referring to Black Sub Saharan Africans. Really important genesis events in Eurasian and West Eurasian history could have occurred in North Africa. Plus there might be post-70ky genetic links between the Middle East and all of Africa: Y DNA E, mtDNA M1....

Maciamo
10-08-17, 08:49
That comes just a few weeks after another study found that Homo sapiens could have reached Australia between 65,000 and 80,000 years ago (https://www.theguardian.com/australia-news/2017/jul/19/dig-finds-evidence-of-aboriginal-habitation-up-to-80000-years-ago), that is some 20,000 years earlier than previously thought. All this is pushing back the date of the first Out-of-Africa migration.

This means that the current age estimates of old haplogroups are wrong too. Yfull has a formation age of 65,000 years for haplogroup C (found among Australian aborigines and many places around Eurasia) and a TMRCA of just 48,000 years. However if these people reached Australia over 65,000 years ago and Europe (as C1a) 45,000 years ago in two migrations from a source in East Africa, the TMRCA has to be older than 65,000 to 80,000 years, and the formation age could be over 90,000 years. As a result, haplogroups CF, CT, BT, A1b, A1, A, A0 and A00 all become older too, with A00 (the Y-chromosomal Adam) possibly well over 300,000 years old, nearly half-way between the time Homo sapiens and Neanderthals diverged from each other.

Fire Haired14
10-08-17, 09:05
@Maciamo,

But what if those human remains are from genetic dead ends that aren't apart of the Out of Africa family.

Maciamo
10-08-17, 09:36
@Maciamo,

But what if those human remains are from genetic dead ends that aren't apart of the Out of Africa family.

If they are anatomically modern humans, they must have come from Africa. What you mean is that there could have been several waves of migration, and that the first could have belonged to older haplogroups than C, like CT or BT. That's possible, but how likely is it that there were many direct migrations from Africa all the way to Australia? It's not even clear today how these people managed to cross the Timor Sea on rickety boats. Boats 50,000 or 80,000 years ago were much less advanced than the ones African migrants use to cross from North Africa to Europe these days, and yet many of them die every month, trying to cross much shorter distances, and knowing exactly where they are going. The ancestors of the Aborigenes didn't know where they were going. They didn't know that Australia existed. Mind, you nobody knew it existed until the Dutch stumbled on it by chance in the 17th century. The Indians, Javanese, Sumatrans, Khmers, Thai, Chinese, Japanese and others had no idea this continent lied just south of Indonesia, as it's not visible and the distance is so big across open seas that even Chinese junks (those that travelled to India and Africa in the 15th century) didn't venture there. It was really quite an exploit for early humans to reach Australia, let alone reach it in sufficient numbers to survive and procreate there! It was not just a bunch of lost fishermen, but entire families. Very puzzling.

bicicleur
10-08-17, 13:14
That comes just a few weeks after another study found that Homo sapiens could have reached Australia between 65,000 and 80,000 years ago (https://www.theguardian.com/australia-news/2017/jul/19/dig-finds-evidence-of-aboriginal-habitation-up-to-80000-years-ago), that is some 20,000 years earlier than previously thought. All this is pushing back the date of the first Out-of-Africa migration.

This means that the current age estimates of old haplogroups are wrong too. Yfull has a formation age of 65,000 years for haplogroup C (found among Australian aborigines and many places around Eurasia) and a TMRCA of just 48,000 years. However if these people reached Australia over 65,000 years ago and Europe (as C1a) 45,000 years ago in two migrations from a source in East Africa, the TMRCA has to be older than 65,000 to 80,000 years, and the formation age could be over 90,000 years. As a result, haplogroups CF, CT, BT, A1b, A1, A, A0 and A00 all become older too, with A00 (the Y-chromosomal Adam) possibly well over 300,000 years old, nearly half-way between the time Homo sapiens and Neanderthals diverged from each other.

I disagree.
IMO these early people in Indonesia and Australia were a branch of haplogroup A that went extinct.
These people were probably also in India were they left their autosomal DNA and contributed to 'Basal Eurasian'.

Maciamo
10-08-17, 15:37
I disagree.
IMO these early people in Indonesia and Australia were a branch of haplogroup A that went extinct.
These people were probably also in India were they left their autosomal DNA and contributed to 'Basal Eurasian'.

But Basal Eurasian is much more recent and linked to haplogroups such as E1b1b, G and H.

80,000 ybp is too old for Basal Eurasian to exist as an admixture. It long predates the migration of Homo sapiens to the Middle East, Central Asia and Europe, let alone the diversification of Eurasian admixtures into Basal, WHG, EHG, CHG, South Asian, etc. That's how Eurasia looked at the end of the Ice Age 12,000 years ago, perhaps as populations got bottlenecked after the LGM.

bicicleur
10-08-17, 17:21
But Basal Eurasian is much more recent and linked to haplogroups such as E1b1b, G and H.

80,000 ybp is too old for Basal Eurasian to exist as an admixture. It long predates the migration of Homo sapiens to the Middle East, Central Asia and Europe, let alone the diversification of Eurasian admixtures into Basal, WHG, EHG, CHG, South Asian, etc. That's how Eurasia looked at the end of the Ice Age 12,000 years ago, perhaps as populations got bottlenecked after the LGM.

Basal Eurasian postdates the split between African and Eurasian, but predates Ust-Ishim.
It could very well be the result of admixture between the 1st wave of AMH out of Africa with the 2nd wave.
The 1st wave wouldn't have left any Y or mtDNA.
H is an Indian clade.
G split too young, only 26 ka, it is not possible to say where it was 40 ka or earlier.

Promenade
11-08-17, 00:32
The Toba super volcano erupted in Sumatra in the period between 75-70,000BC, some claim it's responsible for a genetic bottleneck and reduced the human population to below 5000.

If so these individuals could have been the unlucky early people who left Africa and went straight for ground zero...

I doubt they are related to anyone alive today