Thursday, September 22, 2011

PEOPLES IS PEOPLES... AND APES IS APES

from the September 20, 2011 eNews issue
http://www.khouse.org (visit our website for a FREE subscription)

There were once a much wider variety of human beings on this planet than there are now, according to new genetic analyses of Neanderthals in Europe and Denisovans in East Asia. Modern humans once interbred with these other groups, apparently sharing genetic material that includes the ability to fight off certain diseases. Yet, not all creatures designated as "hominids" are related to humans.

In 2008, a piece of bone and a tooth of what is believed to be a young girl were found in Denisova Cave in southern Siberia, along with stone blades and body ornaments. Twenty years ago the small bone and a tooth would not have been much to go on. These days, however, 40 mg of real bone from a fossil can tell researchers a great deal of information - if the bone contains enough genetic material for researchers to sequence the DNA.

Researchers were able to compare DNA all around, and it turns out that the Denisovan girl and Neanderthals are related, but not directly. According to comparisons of genetic code, the Denisovan shared a common ancestor with Neanderthals and modern humans.

"It amazed me that we found this other extinct group of humans," evolutionary geneticist Svante Pääbo at the Max Planck Institute for Evolutionary Anthropology at Leipzig, Germany, told LiveScience. "When we got this little finger bone from Siberia, I was totally expecting it to be either Neanderthal or modern human. When it was something else, that was totally surprising and shocking to me."

Ancient humans might bear some superficial physical differences from modern homo sapiens, but they were all still humans and able to breed with one another. In fact, interbreeding between modern-form humans and Neanderthals may have given us modern humans certain genes that helped boost our immune systems.

At the least, Neanderthals share key immunity genes with us, namely the HLA (human leucocyte antigen) class 1 gene. HLA proteins are important in helping the body defend itself against new infections. A variant called HLA-B*73 is found both in modern humans and Denisovans.

There's quite a bit of Neanderthal DNA floating around out there in the population. According to researchers, up to four percent of Neanderthal DNA and up to six percent of Denisovan DNA have survived in modern humans. It's been known for some time now that Neanderthals bred with the people whose descendants are now found in Europe and western Asia. Denisovan genes can also be found in the population of Europe and especially in the people of Asia and the oceanic islands.

No Missing Links
For more than a century, Neanderthals were portrayed as brutish, evolutionary missing links. They brought to mind the knuckle-dragging cave man, little better than apes themselves. Those pictures of Neanderthal are sadly incorrect. Evidence consistently points to Neanderthals as an extinct, but completely human, group of individuals. Neanderthals used tools, buried their dead, and even made musical instruments. The Denisovan bones were found with tools and body ornaments, which are both characteristic of human beings.

In the Bible, Adam's son Seth was born as a replacement for Abel, who was murdered by Cain. However, Cain, Abel, and Seth were not the only children Adam and Eve produced. Genesis 5:4 states that Adam lived another 800 years after Seth was born, and he begat sons and daughters. Seth's importance in the story comes from the fact that it is through his descendants that Noah is born. The only human genetic lines that survived the Flood were those that climbed on board the ark – namely, the genes of Noah's three sons and their wives.

With the Flood, God wiped out nearly all of humanity. He preserved one slender group of genes to continue on through the children of Shem, Ham and Japheth. It should therefore be no shock that we find the remains of other extinct humans that don't look exactly like us. Their gene pools were nearly wiped out.

Apes Are Still Apes:
On the other hand, paleoanthropologists are constantly seeking out new fossils they hope will finally provide science with the missing links between apes and humans. The newest human precursor is Australopithecus sediba. A. sediba was discovered in South Africa in 2008 by a little boy and his dog, and later identified as an australopithecine, a cousin of the famous Australopithecus afarensis, Lucy.

While A. sediba provides an exciting new puzzle piece for evolutionary paleoanthropologists, its similarities to humans - just like Neanderthal's differences - are superficial. A. sediba has been lauded for having hands strong enough to grasp tree branches while at the same time have hands that could use tools. Its pelvis is also more curved than other australopithecines, which the researchers believe would have made it easier for females attempting to give birth to babies with larger heads and brains. The fact that A. sediba itself has a small head, with a brain capacity of only 420 cc, doesn't discourage the scientists. They consider A sediba to be a possible human ancestor, and therefore the researchers see a human head-friendly pelvis in A. sediba.  Whether this is a case of, "If I hadn't believed it, I wouldn't have seen it," requires a second opinion.

"They are important fossils and remarkably detailed," said paleontologist Bernard Wood of George Washington University in D.C..  Wood stood among those paleontologists  who were not yet willing to support A. sediba as a human ancestor. "I have some resemblances to Warren Buffett, but I'm not a billionaire," Wood says. "A few resemblances does not an ancestor make."

At the end of the day, A sediba is still an ape. She is an ape with long fingers and a wide pelvis. No tools or jewelry were found with A sediba. The apes did not bury their dead nor play handmade flutes. A. sediba simply represents the longing of paleoanthropologists to fill in the gaps between humans and apes on an evolutionary tree.

The difficulty is that the gaps are fairly large. Each new fossil discovery adds just one more individual to either the human family branches or the ape family branches. As much as paleoanthropologists want the two sets of branches to eventually run into each other, as time progresses, they look more and more like two, many-branched bushes and not one single tree at all.

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