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Recent Revelations about the|
Relationship of Modern Humans in
Europe and East Asia to the Neanderthals
Ever since the discovery of bones in a cave in Neander's Valley, Germany in 1856 there has been speculation and revelations about the relationship of Neanderthals and the modern humans of Europe and West Asia. (Pronunciation: Neanderthal is a German term and German does not have the th sounds that English has. The "th" in Neanderthal just means the "t" is aspirated. So the proper pronunciation is NeanderTal.)
The Neanderthals existed in Europe and West Asia for about two hundred thousand years, from 230,000 BCE to 30,000 BCE. Modern humans arose in Africa about 150,000 BCE and some migrated out of Africa about 50,000 BCE. There was thus about 20,000 years of overlap in the occupation of Eurasia between the two species.
The bones of the Neanderthals were thicker and stronger, probably indicating a heavier musculature, than modern humans. The different skeleton structure meant that modern humans could run/walk much further in hunting outings than the Neanderthals could, perhaps 30 miles per day for modern humans versus 10 miles per day for the Neanderthals. It was easy to believe that modern humans simply outcompeted the Neanderthals for the available food supply and thus the Neanderthals died out.
Based upon skeletal remains there was no evidence that modern humans and Neanderthals interbred. The bones were just one or the other with nothing in between. There was only one skeleton of a child in Portugal that might of have indicated hybridization but it could represent the effects of disease on skeletal structure.
There was the possibility that prevalence of an occipital knot on the back of the skulls of many Europeans was evidence of interbreeding. Neanderthal's had such a knot and non-Europeans do not.
Then about ten years ago scientist learned how to replicate mitochondrial DNA and thus obtain significant amounts of DNA from the miniscule amounts found in Neanderthal bones. The analysis gave some surprising results. A few percent, about 3%, of the genes of Europeans were from the Neanderthals. East Asians had slightly more. It was a surprise to find Neanderthal genes among those of East Asians since Neanderthals never got that far east, but the ancestral home of the East Asians was probably farther west in North Central Asia. Africans have no Neanderthal genes.
The situation is similar to the matter of Amerindian ancestry of people of the American South. Almost everyone claims some Amerindian ancestry and it is usually (1/16)th Cherokee. Originally (1/16)th Cherokee meant that a person had a Cherokee grandparent. But now it is a stable distribution. Two parents of (1/16)th Cherokee ancestry produce children who are (1/16)th Cherokee.
So it is with the Neanderthal ancestry of Europeans and East Asians. Everyone is (1/40)th to (1/30)th Neanderthal.
But recent research has produced a startling revelation. Researchers in the United States and the United Kingdom decided to focus on Neanderthal genes among particular categories of genes. What they found is amazing. Among the genes having to do with skin pigmentation and hair form and color about 70 percent of the genes of Europeans and East Asians are from the Neanderthals. This makes sense concerning skin pigmentation. This phenomenon was not necessarily limited Europeans and East Asians. They just happened to be the sample the researchers chose to start their study with.
In temperate zones people with dark pigmentation do not get enough vitamin D from the Sun's ultraviolet light and consequently develop such conditions as rickets. Their survival rate is lower and over time the people with dark pigmentation die out leaving the species with only people of light pigmentation. The Neanderthals, as a result of their two hundred thousand year sojourn in Eurasia, would have had light skin color. The offspring of modern humans and Neanderthals who inherited the lighter skin of their Neanderthal ancestry had a greater chance of survival. After a ten or twenty thousand year period they would be the only ones surviving.
There is no obvious reason that straight hair would have any survival advantage in the temperate zones over tightly curled African hair. Perhaps straight hair keeps one warmer. There is a gradient in hair color in Europe from blonds in the north to brunettes in the south. Those inheriting low pigmentation of skin color would also have been likely to inherit low pigmentation of hair color. There was of course a divergence in this matter between the Europeans and the East Asians.
There were other African features such as thick lips which disappeared among Europeans and East Asians despite there being no obvious survival element accounting for their disappearance.
The results of this research have just been published in the premier science journals of the United States and the United Kingdom. The article of the American researchers is in the January 31st, 2014 issue of Science online. The article of the researchers in the United Kingdom is published in a January 29th issue of Nature online. The results of the two lines of research are the same. The conclusion of both was that modern humans in Europe and East Asia, as a result of their mixing with the Neanderthals, ended up looking visually like the Neanderthals.
Years ago an anthropologist was asked if a Neanderthal person would be identifiable as such among modern humans. The anthropologist answered that if the Neanderthal was properly dressed and groomed no one would think that he was beyond the normal variation in human appearances. It was thought at the time that this statement was valid because of a natural resemblance of the intrinsic appearance of Neanderthals and modern humans. With the cited research mentioned above we known that modern humans evolved to replicate the features of the Neanderthals, features that had evolved among the Neanderthals in their two hundred thousand year sojourn in the temperate zone. It was not that Neanderthals in Europe resembled modern humans, it is that modern humans in Europe ended up duplicating the appearance of Neanderthals.
If the Neanderthals had not been in Eurasia when the modern humans came from Africa the modern humans would have evolved in the same way the Neanderthals did, for the same reasons that drove the evolution of the Neanderthals but the modern humans did not have to wait for the chance emergence of the genes. The Neanderthals already had the genes and mating brought those genes into the gene pool of the modern humans.
The researchers also investigated the genes having to do with speech. There were no Neanderthal genes among Europeans and East Asians in this category. This lends support to the belief that Neanderthals did not have the faculty of speech. They might not have had essential anatomical structures such as vocal cords. Chimpanzees and gorillas do not have the anatomy required for speech.
A lack of speech would explain the pathetic technology of the Neanderthals. They had basically only what was called a hand-ax; basically only a broken rock with a sharp edge. The creation and use of this tool could be communicated visually from one Neanderthal person to another without the use of speech. But any more complicated discovery of one Neanderthal could not be passed on to another and hence died with the discoverer. This would explain how the Neanderthals could have spent two hundred thousand years with a technology consisting of hand-axes. Researchers claim that chimpanzees and gorillas have an I.Q. of about 95 compared to an average I.Q. of humans of 100, yet chimpanzees and gorillas have no technology despite a couple million years of existence. Well, perhaps chimpanzees do have a technology of sorts: a stick to poke into termite nests. Thus the Neanderthals could have been intelligent but without the power of communication that intelligence was largely wasted.
Thus the end result of the contact of modern humans from Africa and the Neanderthals of Europe and West Asia was apparently talkative, taller, more graceful Neanderthals. That is say, if there could have been an observer in Europe from 30,000 BCE to 20,000 BCE that observer would have seen only seemingly minor changes in the appearances people of the area over that period of time. It was as though the Neanderthals adopted the bone structure of the Africans and their vocal communications but otherwise continued to look the same as they had looked for a hundred thousand years. So to all appearances the Europeans and East Asians are simply the Neanderthals of ancient times.
Sriram Sankararaman, Swapan Mallick, Michael Dannemann, Kay Prüfer, Janet Kelso, Svante Pääbo, Nick Patterson & David Reich, "The genomic landscape of Neanderthal ancestry in present-day humans", Nature, online (29 January 2014)
Benjamin Vernot & Joshua M. Akey, "Resurrecting Surviving Neandertal (sic) Lineages from Modern Human Genomes," Science online, (31 January 2014)
Carl Zimmer, "Interbreeding with Neanderthals," Discovery, (4 March 2013) .
(To be continued.)
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