http://constantincretan.wordpress.com/2011/09/12/the-first-cro-magnon-was-a-hybr..."
THE FIRST CRO-MAGNON WAS A HYBRID “EVE”, WITH A HOMO SAPIENS MOTHER AND A HOMO NEANDERTHALENSIS FATHER
septembrie 12, 2011
There have been several genetic studies lately which have set out to verify whether crossbreeding between Homo sapiens and Neanderthal has taken place. The most plausible answer is that crossbreeding has indeed occurred, taking into account that the genome of a modern human has 1-4% Neanderthal genes, with the exception of the Sub-Saharan African population.
Nonetheless, let us analyse the way in which these genes could have been transmitted from the Neanderthal to the modern human.
Cross breeding between a Sapiens male and a Neanderthal female would have led to descendants carrying a mitochondrial DNA (mt-DNA) inherited exclusively from the mother. In this case, we should be able to find humans today that have an mt-DNA haplogroup identical to that of the Neanderthal, very different from the Sapiens. But this mt-DNA haplogroup has never been found in a modern day human. If breeding between Sapiens males and Neanderthal females has indeed taken place, the hybrids that resulted were either infertile or eliminated through natural selection – immediately or within a number of generations. In any case, there are no descendants of Neanderthal females on Earth today.
Following crossbreeding between a Neanderthal male and a Sapiens female, the result would have been male descendants carrying the Y chromosome inherited from the Neanderthal. Their descendants on a male line would still wear the same Neanderthal Y chromosome today. But all human y-DNA haplogroups today are Sapiens. No male has been found in this age to carry the Neanderthal Y chromosome. If ever there have been male hybrids born to Neanderthal males and Sapiens females, they were eliminated in the breeding process – straight away or within several generations. In any case, if they have ever existed, they no longer have descendants today.
The only possibility that could have led to the current state of things, namely the existence of Neanderthal genes in the modern human genome and the absence of maternal haplogroups (mt-DNA) or paternal haplogroups (y-DNA) of a Neanderthal origin, is that the modern Northern human (Cro-Magnon) has inherited its genetic material exclusively through females with a Neanderthal father and a Sapiens mother. This is the only possibility for Neanderthal y-DNA and mt-DNA to be absent from the human genome, while other Neanderthal genes are present.
We cannot completely exclude the possibility that these hybrid females, with a Neanderthal father and a Sapiens mother, developed in different places at different times, in those areas where Sapiens and Neanderthals lived together. However, far more probable is that modern humans, the Cro-Magnon, all have their origin in a single hybrid female, whose descendants have been so exceptionally endowed that they managed to eliminate not only the Neanderthal, but also the ’pure’ Sapiens, the Sapiens that was not ’contaminated’ with Neanderthal genes, so that the ’pure’ Sapiens only lives in Sub-Saharan Africa nowadays. The monocentric theory regarding the rise of the hybrid Cro-Magnon is more plausible than the polycentric one for the same reasons that the monocentric Sapiens theory is more plausible than the polycentric one – reasons which I will not go into again here. In addition, the probability of a recurrence in time and space of the scenario whereby the only hybrid with descendants is a female with a Neanderthal father and a Sapiens mother is almost zero. But perhaps the strongest argument in favour of the monocentric theory concerning the rise of the Cro-Magnon is that, although Neanderthal genes only represent 1-4% of the Eurasian genome today, the genes in the HLA system represent Neanderthal variations of up to 50% in the case of Eurasians, according to a very recent study published by ’Science’ Magazine’. This too would have had a practically zero probability of occurring, in the case of the polycentric rise of the Cro-Magnon born to Neanderthal-Sapiens hybrid females.
If this hybrid did not have exceptional advantages over the ’pure’ Sapiens and was only an accident, the current proportion of Neanderthal DNA would have to be, after so many generations, a lot lower than 1-4%. Following random breeding between hybrids and ’pure’ Sapiens, even in the small areas inhabited by such hybrids, the proportion of Neanderthal genes would have soon dropped below 1% within only a few generations. However, this proportion has been maintained above 1% for thousands of generations and this can only be explained by the fact that the descendants of the first hybrid female had exceptional qualities – something which enabled them to exterminate all competing pure populations, the Neanderthal as well as the Sapiens.
The entire current population in Eurasia originates from this ’Eve’, who had a Neanderthal father and a Sapiens mother. This hybrid female and its descendants have been the first generation of Cro-Magnons.
P.S. The theory that the Cro-Magnon is not a Sapiens, but rather a Sapiens-Neanderthal hybrid, could be tested quite easily, by evaluating the proportion of Neanderthal DNA in the Cro-Magnon genome. If the result only finds Cro-Magnons with Neanderthal genes in their genomes, then the Cro-Magnon can no longer be seen as a Homo Sapiens, but as a Sapiens-Neanderthal hybrid. "
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