Thursday, September 16, 2010

Evolution Hybridization Among Species Not Rare Neanderthals Bred with Humans

Tags: Evolution Hybridization Among Species Not Rare, Neanderthals and Humans Hybrid, Survival

This is a fascinating article about fertile hybrids exceptions in both the animal and plant kingdoms. The survival of they hybrids depends on their ability to reproduce and to compete with their parent species for survival. If fertile, the hybrids can survive by leaving their home environment to live in areas not acceptable to their parents’ breed. Plants seem to be the most adaptable, perhaps with the help of the wind and other carriers as animals and birds and bees.

I don’t know if my knowledge is wide enough to confirm my observation that northern Europeans and northern Asians seem to have a more violent history than other parts of the world. When survival becomes more difficult in the very cold and harsh climates during the ice Ages, the chief reason Homo sapiens survived is probably due to Neanderthals imparting lighter skin, musculature, and the Homo sapiens more violent than competing species. Perhaps competing with other humans in villages made them more violent than more isolated Neanderthals.

A more recent example is the Passing on of deadly diseases as the European emigrants passed on Small Pox accidentally and deliberately to wipeout as high as 99 percent of Native Americans. I remember a Star Trek episode from long ago where the Europeans were dessimated by biological warfare with the Chinese taking over. We tried to develop an Japanese specific biological weapon, but failed during World War II and an Asian one during the Nixon regime starting in 1969.

The Scots and Scots-Irish had to be especially tough to survive in tough climates and one thousand years of continuous invasions. These warrior genes in the Scots-Irish who make up a majority of the Republican Party tend to be great in winning elections and fighting wars, but poor in governing as we have seen in both the Reagan and Bush administration when the crazies got into power.

I hope to God that Republicans don’t win the House or else we will see nothing done, Clinton type unfair investigations of corruption, and the corporate takeover of government. Republicans has promised they will only do investigations.

The Jews survived the forever Pogroms, not by an act of God, but survived by developing certain intellectual skills such as IQ and creativity, and scholarship quite noticeable throughout the world.

DNA studies indicate that the light skin genes were the major part of the Neanderthal DNA preserved by modern humans. The light skin allowed the production of vitamin D in the skin and darker skin humans died.

I heavily excerpted NY Times Sean B. Carroll article so I recommend you read the whole article.

Jim Kawakami, Sept 16, 2010,

Evolution Hybridization Among Species Not Rare Neanderthals Bred with Humans

NY Times Sean B. Carroll, Sept 13, 2010, Sean B. Carroll is a molecular biologist and geneticist at the University of Wisconsin. On May 15, 1985, trainers at Hawaii Sea Life Park were stunned when a 400- pound gray female bottlenose dolphin named Punahele gave birth to a dark-skinned calf that partly resembled the 2,000-pound male false killer whale with whom she shared a pool. The calf was a wholphin, a hybrid that was intermediate to its parents in some characteristics, like having 66 teeth compared with the bottlenose’s 88 and the 44 of the false killer whale, a much larger member of the dolphin family. …

While one might think that these oddities are examples of some kind of moral breakdown in the animal kingdom, it turns out that hybridization among distinct species is not so rare. Some biologists estimate that as many as 10 percent of animal species and up to 25 percent of plant species may occasionally breed with another species. The more important issue is not whether such liaisons occasionally produce offspring, but the vitality of the hybrid and whether two species might combine to give rise to a third, distinct species.

While several examples of human-bred animal hybrids are well known and can thrive in captivity including zorses (zebra-horse), beefalo (bison-beef cattle) and, of course, mules (donkey-horse), naturally occurring animal hybrids have many factors working against their longer-term success.

One of the main obstacles is that, even if members of different species might mate, when the two species are too distant genetically or carry different numbers of chromosomes, the offspring are usually inviable or infertile (like zorses and mules), and are therefore evolutionary dead ends. A second problem is that any hybrid will usually be vastly outnumbered and outcompeted by one or both parent species.

But because species hybrids create new combinations of genes, it is possible that some combinations might enable hybrids to adapt to conditions in which neither parent may fare as well. Several such examples are now known from nature. Furthermore, DNA analysis is now allowing biologists to better decipher the histories of species and to detect past hybridization events that have contributed new genes and capabilities to various kinds of organisms including, it now appears, ourselves. …

Analyses of the overall genetic distance between Neanderthals and modern humans reveal that our DNA is 99.84 percent identical to that of Neanderthals. This small divergence indicates that the two lines split off from each other about 270,000 to 440,000 years ago. The fossil evidence shows that Neanderthals were restricted to Europe and Asia, whereas Homo sapiens originated in Africa.

Various kinds of evidence indicate that modern humans migrated out of Africa and reached the Middle East more than 100,000 years ago and Europe by about 45,000 years ago, and would have or could have encountered Neanderthals for some time in each locale. The crucial question for paleontology, archaeology, and paleogenetics has been what transpired between the two species. To put it a little more crudely, did we date them or kill them, or perhaps both?

If the former, then there could be a bit of Neanderthal in some or all of us. The first comparisons of small sections of Neanderthal DNA did not indicate any hybridization, and the lack of interbreeding became a widely accepted conclusion.

That remained the case until this year, when a much greater portion of the Neanderthal genome was obtained by Svante Paabo and colleagues at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. It now appears that 1 percent to 4 percent of the DNA sequence of Europeans and Asians, but not Africans, was contributed by Neanderthals mixing with Homo sapiens, perhaps in the Middle East 50,000 to 80,000 years ago. It is possible that some Neanderthal versions of genes enabled modern humans to adapt to new climates and habitats.

The discovery of hybrid species and the detection of past hybridizations are forcing biologists to reshape their picture of species as independent units. The barriers between species are not necessarily vast, unbridgeable chasms; sometimes they get crossed with marvelous results.

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