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Related: About this forumLast Common Ancestor of Neanderthals and Modern Humans Still a Mystery
It appears that the search for and identification of fossil remnants of the last common ancestor (termed 'LCA' by paleoanthropologists) of both Neanderthals and modern humans, long a subject of debate among scientists studying human evolution, will remain a mystery. At least for now.
So suggests the conclusions of a PNAS-published study conducted by Aida Gómez-Robles, lead author of the paper and a postdoctoral scientist at the Center for the Advanced Study of Hominid Paleobiology of The George Washington University, and an international team of colleagues.
The study, the first of its kind, used quantitative data collection and analysis techniques to reconstruct a mathematically-informed model of the probable dentition of the Neanderthal/modern human LCA. They then compared known fossil dentitions of classified species of Homo (the genus of great apes that includes modern humans and species closely related to them) to the reconstructed LCA model.
Fossil examples from the European Middle Pleistocene (ca. 781 to 126 thousand years ago) and others from Africa were used in the comparison. They included fossils of approximately 1,200 molars and premolars from 13 species of Homo, including fossils from the well-known Atapuerca sites in Spain, which have yielded some of the earliest known fossils of ancient humans in Europe. They considered two alternative Neanderthal/modern human divergence times based on previous research: 450 ka (thousand years) based on molecular clock estimate research results; and 1 Ma (million years) based on the morphological (physical form and structure) affinities among the various subject species found in the fossil record.
http://popular-archaeology.com/issue/09012013/article/last-common-ancestor-of-neanderthals-and-modern-humans-still-a-mystery
Also:
No known hominin is ancestor of Neanderthals and modern humans, research says
The search for a common ancestor linking modern humans with the Neanderthals who lived in Europe thousands of years ago has been a compelling subject for research. But a new study suggests the quest isn't nearly complete.
The researchers, using quantitative methods focused on the shape of dental fossils, find that none of the usual suspects fits the expected profile of an ancestor of Neanderthals and modern humans. They also present evidence that the lines that led to Neanderthals and modern humans diverged nearly 1 million years ago, much earlier than studies based on molecular evidence have suggested.
http://phys.org/news/2013-10-hominin-ancestor-neanderthals-modern-humans.html
Journeyman
(15,036 posts)or did they decide he's under-qualified?
tclambert
(11,087 posts)or eyebrow
http://www.google.com/imgres?imgurl=&imgrefurl=http://www.bbc.co.uk/onthisday/hi/dates/stories/november/10/newsid_2516000/2516417.stm&h=178&w=238&sz=9&tbnid=JuZ2051qiTlFZM:&tbnh=125&tbnw=167&zoom=1&usg=__sgTaYXyOrA8pMTzR91da5VtWosw=&docid=E8qPoSfk8StLpM&sa=X&ei=XW5mUvDyN8Oh2gW-i4CwAw&ved=0CDkQ9QEwBQ
And then there's this guy:
http://www.google.com/imgres?imgurl=&imgrefurl=http://24ahead.com/blog/archives/000472.html&h=360&w=340&sz=39&tbnid=e8JisW5Zy-y9xM:&tbnh=116&tbnw=110&zoom=1&usg=__C_nvQZ-bIDIqVh4koeL5t-q5CWY=&docid=s4dqdbVSRM4pbM&sa=X&ei=IG5mUoGHNYST2gXBpoDQBg&ved=0CDAQ9QEwAQ
Ichingcarpenter
(36,988 posts)I guess the wikipedia page needs to be edited.
wikipedia:
heidelbergensis (sometimes called Homo rhodesiensis) is an extinct species of the genus Homo which lived in Africa, Europe and western Asia from at least 600,000 years ago, and may date back 1,300,000 years. It survived until 200,000 to 250,000 years ago. It is very likely the direct ancestor of Homo sapiens in Africa and the Neanderthals in Europe, and perhaps also the Denisovans in Asia.
heidelbergensis had a larger brain-case with a typical cranial volume of 11001400 cm³ overlapping the 1350 cm³ average of modern humans and had more advanced tools and behavior, it has been given a separate species classification. Male heidelbergensis averaged about 5 ft 9 in (1.75 m) tall
http://en.wikipedia.org/wiki/Homo_heidelbergensis
Now my question is how did his teeth compared to the other two?
Enthusiast
(50,983 posts)As new discoveries are made, the old information becomes "dated" and irrelevant. There are more fossils to be found, fossils which could give us a more complete picture. But there will never be a complete fossil record as circumstances required for fossilization are rare. It's a fascinating subject.
Where do Denisovans fit in? http://www.sciencemag.org/content/342/6156/321.summary
It seems the tree of evolution was a truly bushy one.
Ichingcarpenter
(36,988 posts)I asked two questions so I don't know what you are saying yes to...
I looked at the study and didn't find any reference to Heidelberg man and his relationship to the three branches on teeth study.
Enthusiast
(50,983 posts)The anthropologists and paleontologists can't agree on what to do with Homo heidelbergensis. They need more fossil evidence. Some continue to think this hominid variation was a common ancestor, others are now uncertain.
MisterP
(23,730 posts)especially since human fossils have such a priority that we can see exactly how gradual the process of change over time is (or isn't)
http://en.wikipedia.org/wiki/Chronospecies
Enthusiast
(50,983 posts)tclambert
(11,087 posts)It leaves room for them to find a more recent direct ancestor of both. The fact that they think Denisovans may have also descended from H. heidelbergensis may indicate that a later branching occurred.
The last part of post that says there are "no known common ancestors" is clearly wrong.
I remember someone pointed out that the spotty nature of the fossil record means every new "missing link" discovered actually creates a new gap in the chain, and new missing links to search for.
Edited to add: And what Enthusiast said about the "tree" of life being "bushy," means at some point a teenage Cro Magnon girl may have insisted on dating a Neandertal boy, despite her parents' disapproval. As far as I know, anthropologists still argue whether or not we modern humans contain a little Neandertal. (Leonid Brezhnev's eyebrows come to mind.)
Ichingcarpenter
(36,988 posts)who they studied and heidelbergensis know existence doesn't seem enough time to explain the inconsistencies
I do find this fascinating of course
tclambert
(11,087 posts)Branching doesn't have to occur right at the end of their existence. They overlapped Neandertals for quite a long time. There could have been some fooling around between them. Branching doesn't have to happen in a clear, clean manner. They could recombine and re-separate over and over. If they acted much like modern humans, they must have raided each others' camps and stolen women many, many times.
Frankly, the more I think about it, the more tangled the whole thing seems.
Enthusiast
(50,983 posts)Human evolution is a convoluted mess. Apparently there was a whole bunch of crossbreeding along the way. Imagine that.
Ichingcarpenter
(36,988 posts)which is also what it says which puts it in the Neanderthal time zone in europe.
It seems that Heidelberg man is an enigma whose history. must be re written.
Some bones suggest he was 7 feet tall in Africa. I hope more discoveries will solve this mysterious cousin.
Enthusiast
(50,983 posts)Me too.
Enthusiast
(50,983 posts)on the NeanderthalCro MagnonDenisovan crossbreeding question. The DNA doesn't lie. You can even send your DNA away to have it analyzed to determine the % of Neanderthal DNA you might carry. It's common for Europeans to have around 2% Neanderthal DNA.
Then where do we place the mysterious Homo Floresiensis? http://www.sci-news.com/othersciences/anthropology/science-homo-floresiensis-01226.html
Weird, wild stuff.
tclambert
(11,087 posts)This must have come out in just the last few years. Amazing how our "knowledge" changes.
The crossbreeding really complicates things. What with suspicions that a number of human diseases came from perverts getting naughty with chimpanzees, we could see lower branches crossing with higher branches. (Humanzee! http://en.wikipedia.org/wiki/Human-chimpanzee_hybrid)
Basically anything that can crossbreed . . . will.
Enthusiast
(50,983 posts)I didn't know about the attempts to crossbreed humans and chimpanzees. Well, I guess there have been no actual good attempts.
On a related note, human lice are unusual. Human head lice are peculiar to our species, but human pubic lice are distinctly different than our head lice, being more closely related to....ape lice. Unreal. I'm not making this up.
starroute
(12,977 posts)There's been increasing divergence between the people who study the fossils and artifacts and the people who analyze the DNA. In particular, it's beginning to seem that the dates provided by DNA studies go back only half as far as what the fossils would suggest.
This is especially relevant to the out-of-Africa question for modern humans. DNA suggests a divergence date for all non-African DNA of not much more than 50,000 years ago, but this produces some strange kinks in the migration scenario. They have to assume that the modern humans who were already living in Arabia 125,000 years ago completely died out and that all non-Africans are descended from a later wave of migration that took the "beachcomber express" around the coasts of the Indian Ocean, multiplying rapidly as it went, and reached Australia within just a few thousand years.
Concluding that the DNA clock has been miscalibrated -- that it assumes mutations happened more quickly than they really did and that human generations were shorter than they really were -- would go a long way towards sorting things out. It would also make sense of the recurring Chinese claims to have dated certain modern human fossils at more than 100,000 years old. And it would clarify just when and where cross-breeding with Neanderthals and Denisovans was likely to have occurred.
Enthusiast
(50,983 posts)I'm always on the lookout for new developments.
starroute
(12,977 posts)Maybe it's just that Richard Dawkins rubs me the wrong way, but I've been getting a feeling that the DNA lab analysis types have far too much clout and have been using it to spin a pack of unlikely scenarios. I'd love to see the hands-in-the-dirt types get some of their own back.
In addition, there's a certain amount of lingering racism in the DNA-based scenarios. When I was in college, the orthodox position was still that modern humans had evolved in Europe, and the possibility that they had appeared first in the Middle East was a radical new idea. Since then, the out-of-Africa theory has become undeniable -- but there's a strong desire to claim that humans only got to the Middle East about 50,000 years ago and reached the rest of the world, including Europe, over the 10,000 years that followed.
The idea that there were people in the Middle East, and India, and Southeast Asia, and even Australia at a time when Europe was still inhabited only by Neanderthals -- and that those areas of the world may consequently have cultures that are deeper and more mature than our own -- is anathema to most Americans. But it does seem to be the direction in which things are going.
There's a pretty good article about the ongoing disputes at http://www.nature.com/news/human-migrations-eastern-odyssey-1.10560
Enthusiast
(50,983 posts)I have long been interested in the coastal migration concept. It's hard for us to wrap our minds around a coastline 300 feet below today's sea level. There would be no easier life than on the coast for early modern humans. Sea mammals would be such easy prey. And migration would have been much easier than with today's high sea level.