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Tuesday, May 19, 2015

Modern Human in Laos Shares Cave with Homo Erectus Soloensis Hybrid 63 Thousand years Ago

In  2009, in a cave known as Tam Pa Ling in the Annamite Mountains of present-day Laos, the oldest modern human fossil in Southeast was found.  First reported in 2012 in the Proceedings of the National Academy of Sciences,the discovery pushed back the date of modern human migration through Laos by as much as 20,000 years. Previously we had only obtained evidence from the coasts and islands of Indonesia, and it was unknown whether examples of modern human had made it this far inland by that time. The fossil was determined to be somewhere between 46,000 and 63,000 years old.

The very next year, a jaw bone of the same relative age was found in the same locale...but this one had a mix of modern homo sapien and more archaic traits.

In addition to being incredibly small in overall size, this jaw has a mixture of traits that combine typical modern human anatomy, such as the presence of a protruding chin, with traits that are more common of our archaic ancestors like Neanderthals – for example, very thick bone to hold the molars in place,” this from University of Illinois anthropology professor Laura Shackelford,  co-leader of the expedition withanthropologist Fabrice Demeter of the National Museum of Natural History in Paris.

She went on to say, “Some researchers have used these features as evidence that modern humans migrating into new regions must have interbred with the archaic populations already present in those regions. But a more productive way to look at this variation is to see it as we see people today – showing many traits along a continuum."

My question would be "More useful to whom?"

We don't see people today with the jaws of archaic humans. Just like we don't see people today with eyes as big as Neanderthals, or flaring cheekbones as wide as Red Deer Cave People, or brains as small and advanced as 'the hobbit."
During this time period, 46,000 to 63,000 years ago...we see perfectly modern homo sapien sapient not only in Laos, but also in Australia, the Levant, the Middle East, and possibly Africa with little or no archaic traits.  Soon after that we see them in Europe, albeit with some definitively Neanderthal charactaristics (as opposed to "like Neanderthal") in the form of "Cro-Magnon" man. In all of these places excepting possibly  the Middle East and the Levant, we see separate populations of more archaic forms living alongside the "moderns."
This is exactly what the DNA evidence tells us we should find in the fossil record: at least some of the archaic retrogression from Neanderthal and Denisova occurred during this time period, and the retrogression of Microcephalin D from a third hominid as well as introgression from an African archaic took place around this time as well. "Mungo Man's" LM3 DNA was likely inserted into a "ghost population" that bred with us or one of our own lineages around this time or somewhat earlier, to boot.

Finding a homo erectus/human hybrid next to a homo sapien sapient is exactly what we should have expected to find in Laos, due to the circumstantial evidence we've been accumulating in South East Asia over the past 50 years.

Let's look at Mungo man.
At 45 to 60 thousand years of age, he may be the the first undisputed modern Hss on record.
Sure, there were Hss in southern China, north and east Africa, and the Middle East/Levant long before Mungo Man. But all of them have some trait or other that makes them somewhat less than fully modern. For instance, the ones in Africa are still often missing chins and a definite archaic known as Iwo Eleru is still found there up until the end of the Paleolithic, and the ones from south China seem like they've picked up a few erectus traits from hybridization during that early epoch and have enormous teeth, even up until 18 thousand years ago. Up until 10,000 years ago Balangoda man in Sri Lanka still has lots of archaic traits as well.
Alternatively, I've never heard it claimed that Mungo man had any retained archaic traits...and in fact he is said to be extremely gracile for a Paleolithic human. We don't really see such light boned humans again in the fossil record until around the dawn of the agricultural revolution.

But not long after Mungo Man, we start seeing more robust Hss taking over Australia. At the end of the Ice Age, humans with definite homo erectus traits such as the Kow Swamp people start showing up on the shores of that continent.
(If you don't think that the Kow Swamp people's archaic traits are erectus-like,  then most likely you've imbibed one scientific faction's kool-aid, and it's beyond the scope of this post to explain why you're wrong, but I encourage you to Google it and learn about the opposing camps of thought).
Present Australian aborigines even have thicker skulls than Mungo Man had, and are considerably shorter.

Meanwhile, between the time of Mungo man and modern Aborigines, we know that something OTHER than Hss lived in Southeast asia.
Sure, the homo erectus soloensis fossils keep flipping back and forth between 27 thousand years ago, 100,000 years ago, and over 200,000 years ago.
But we have "the hobbit" surviving in Flores until 12,000 years ago. We have Microcephalin D which introgressed into our genome from a hominid that split off from our line 1.7 million years ago, and it most likely introgressed into our genome somewhere in Indonesia around 35 thousand years ago. We have the implied presence of Denisova in Southeast Asia at this time as well, through the high rate of gene flow into Melanesians.

The most likely, common sense thing to assume from all of this is that the ancestors of Mungo Man skirted around much of Southeast Asia to get to Australia, but left descendants all through Sundaland in close proximity to these various archaic hominids. Later those descendants who didn't make it to Australia hybridized with the homo erectus descendants that then populated most of Sundaland.

I would say that these hybrids are the ones that later took Mungo Man's place in Australia, absorbing them as they took Australia, but I'm afraid it's more complicated that that.

You see, though he is anatomically modern, Mungo Man is not our ancestor. His "mitochondrial Eve" is nearly 70 thousand years older than ours. His lineage split off from ours after Neanderthal, but before the common ancestor of all humans living today.

We know that Mungo Man was soon followed into Southeast Asia and eventually Australia by members of our own lineage, because of the current distribution of our own DNA through the regions and the circumstantial evidence of various isolated tribes throughout Southeast Asia and Australia.
Mungo Man's DNA is extinct, though we have a rare evidence of his hybridization with our own lineage due to an insertion into some modern peoples' chromosome 11 that looks a lot like his mitochondrial lineage's doing.

So what can all this tell us about the finds in Laos?

Well, we know that a representative of Mungo Man's larger LM3 population was in Sundaland at this time, as well as a representative of the descendants of homo erectus. We know that though the East Coast of china was at least partially occupied by questionably modern humans by 40 thousand years ago too.
But even up until 35 k or so there are Denisovans and Neanderthals in Siberia, and Red Deer Cave people persist in Southern China until 12 thousand years ago or more.

Shackelford describes the archaic jaw as having "traits that are more common of our archaic ancestors like Neanderthals – for example, very thick bone to hold the molars in place,”

I believe she used the phrase "like Neanderthals" to obscure the obvious. A "very thick bone to hold the molars in place" is not exclusive to Neanderthals. Not having such a jaw is one of the things that set modern Hss apart from ALL OTHER HOMINIDS. Seeing as how the Laos jaw is exceedingly small, and Neanderthal jaws are huge, a better match would be the phrase "like homo erectus."

Neanderthals have never been found anywhere near Laos. And while Melanesians show high levels of Neanderthal introgression, it's generally agreed that the Neanderthal genes were carried there by homo sapiens who picked them up somewhere in Eurasia. While the Laos jaw COULD be an example of one of these Hss hybrids coming into Indonesia from the West, it seems odd that the Laos environment would shrink the Neanderthal hybrid down to pygmy size while leaving his Hss cave-mate's lineage  alone. What's more, the fact that they were in Laos, which would not have been as conducive to human survival as the coasts to the south, and pressed up against territory to the north that would have been occupied by the ancestors of the Red Deer Cave people*, together with the fact that these are probably representatives of two different population lineages pressed into the same cave systems much like what was occurring between Neanderthals and Denisovans in the Altai region  possibly less than 10 thousand years later...leads me to believe that these guys were basically pushed into Laos by an invading people coming down into Indonesia from the northern river systems of India. Neanderthal hybrids, more robust than LM3.

I believe it's much more likely that the Neanderthal hybrids were the invaders from the west who sent these two populations scurrying into Laos. Melanesian introgression works better with a model where the Neanderthal hybrids entered Sundaland sometime AFTER 43k ago. Though they didn't test Mungo Man for Neanderthal genes before he was reburied, he is so gracile and so modern that it's hard to imagine him having any Neanderthal introgression at all. Australians have our lineage's DNA, and therefore replaced/absorbed Mungo Man, and they have less Neanderthal than Melanesians. this necessitates at least three waves of Hss into Indonesia and Southeast Asia, and we have no fossil evidence that any of them occurred before the eruption of Toba some 70k ago. Microcephaline D is not introgressed into our lineage until around 30k ago, though it is possible that it introgressed into LM3's (Mungo Man's) genome before that date, and that a population of LM3 descendents gave the introgressed erectus gene to us through assimilation.

We could solve this better if the scientists let us know whether this modern human from Laos has more traits in common with the slightly later "Cro-Magnon," (which is definitely a Neanderthal hybrid but also a modern Hss) or with Mungo Man (who is definitely a non-hybrid modern Hss but from a different lineage than our own).. But it still seems un-PC at the moment even to admit that Cro-Magnons or the even more Neanderthaloid Ibero-Maurusians are any more hybrids than we were, most likely because scientists spent the last 50 years trying to play that down...never expecting that the lid would be blown off their theories with the Neanderthal genome and the proof of introgression we know and love today.
Even the Portugal hybrid has been put back on the table, though mentioning him would get you laughed out of the faculty staff room just 10 years ago.
But we haven't gotten public apologies from any of those brutaly finalistic anti-multiregionlists we heard so often from back in the 80s and 90s.
No sir.

My bet is that the Laos modern is more akin to Mungo Man than he is to us OR Cro-Magnon, and that if they were to extract his DNA it would prove to be a descendent of LM3 and a sibling to Mungo Man.
If he is somehow from a DNA lineage that still exists today...I would bet that he is NOT from the Neanderthal hybrid invaders (us) marked by Y Chromosome D, or K and it's descendants...unless the fossil actually has Neanderthal traits that they didn't bother to mention.
And if by some chance he is of Y Chromosome C and does not have any Neanderthal traits at all, it may mean that C was originally NOT a Neanderthal hybrid and has picked up Neanderthal genes from invading populations of D and K over the past 60 thousand years.
All of these things would be "useful" to know.
And it would be nice if they would come clean and describe exactly what they mean by "modern" and "like Neanderthal," even when doing interviews for laymen.

The "modern" Laos fossil may alternatively be a member of the "ghost population" that brought LM3's mutant chromosome 11 insert to the rest of the world, though that seems to have happened much earlier to have introgressed at 10% into San bushmen in the badlands of Africa.
It could even be a member of Y Haplogroup F, which is occasionally found in East Asia and Tibet as a lesser lineage in a population dominated by C, D, or descendants of K.
This would also be useful to know.

As far as the more "archaic" jaw is concerned, the most likely scenario is that it is a hybrid of soloensis or the hobbit and descendents of LM3(Mungo man) or a similar population. It's possible that it could be a member of our own Haplogroup C that dominated erectine populations as it travelled into East Asia in a second wave following LM3, but doubtful; C seems to be associated with a different hybridization event that took place in Sri Lanka in the form of Balangoda Man and did not result in a massive molar support s (though its jaw IS larger than moderns) and did not result in a huge reduction in overall size, and I hope that if it looked like Balangoda the scientific team would have said "like Balangoda" rather than "like Neanderthal." Six foot Balangoda moving into Laos and absorbing Southeat Asian erectines, perhaps.

I don't have all of the answers, but that's the point: it's complicated and it definitely isn't linear.
However, I do not see how assuming that everything from Neanderthal to Red Deer Cave people to the Hobbit to Kow Swamp to Mungo Man were" showing many traits along a continuum" is useful at all for the purpose of obtaining models of population movements for the prehistoric past of East Asia. Nor do I see how it is useful in discerning how we picked up each individual trait from widely varying once-isolated populations to become what is considered an "anatomically and genetically modern human" today.
In fact, when I read such things I wonder whether these people are trying cover up the fact that the multi-regionalists have beaten them as of the turn of the century, or whether they just don't realize it and are in a state of denial.
Or are they just being intentionally incredibly vague until they can get the funding to do what's necessary and get the answers that we need by dredging sunken Sundaland's river basins and former shores?
I have a peer who, like Shackelford, seems to want to lump all hominids into just one species. He has pointed out that Neanderthals and humans are nearly 99% the same.
Thing are lions and tigers. It is still useful to make a destinction between the ones who have stripes and the ones who have manes.
And the differences between those two fossils in Laos are way more extensive than the differences between any two "modern" humans living today, even when those two "modern humans" are separated by several continents and 160 thousand years.
If all we're going to do is "look at this variation is to see it as we see people today – showing many traits along a continuum" without continuing to divide these populations into groups with distinctive traits and distinctive DNA lineages, then there's no reason to keep digging at all. There's no "missing link" 46 to 63 thousand years ago; we already 'get' the big picture from that era.
Now that we've established it, the devil is in the details.

Some sites for reference:

*-Unless of course these two populations in Laos hybridized to BECOME the Red Deer Cave people...though that is doubtful as well since their jaws are very distinct and they have no chins.

A very informative debate about this subject can be found on google groups at the link below:!topic/sci.anthropology.paleo/9KnSmrSVKSA


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