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Skulls Found in Africa and in Europe Challenge Theories of Human Origins
NY Times ^ | August 6, 2002 | By JOHN NOBLE WILFORD

Posted on 08/11/2002 3:59:04 PM PDT by vannrox



August 6, 2002

Skulls Found in Africa and in Europe Challenge Theories of Human Origins

By JOHN NOBLE WILFORD

Two ancient skulls, one from central Africa and the other from the Black Sea republic of Georgia, have shaken the human family tree to its roots, sending scientists scrambling to see if their favorite theories are among the fallen fruit.

Probably so, according to paleontologists, who may have to make major revisions in the human genealogy and rethink some of their ideas about the first migrations out of Africa by human relatives.

Yet, despite all the confusion and uncertainty the skulls have caused, scientists speak in superlatives of their potential for revealing crucial insights in the evidence-disadvantaged field of human evolution.

The African skull dates from nearly 7 million years ago, close to the fateful moment when the human and chimpanzee lineages went their separate ways. The 1.75-million-year-old Georgian skull could answer questions about the first human ancestors to leave Africa, and why they ventured forth.

Still, it was a shock, something of a one-two punch, for two such momentous discoveries to be reported independently in a single week, as happened in July.

"I can't think of another month in the history of paleontology in which two such finds of importance were published," said Dr. Bernard Wood, a paleontologist at George Washington University. "This really exposes how little we know of human evolution and the origin of our own genus Homo."

Every decade or two, a fossil discovery upsets conventional wisdom. One more possible "missing link" emerges. An even older member of the hominid group, those human ancestors and their close relatives (but not apes), comes to light. Some fossils also show up with attributes so puzzling that scientists cannot decide where they belong, if at all, in the human lineage.

At each turn, the family tree, once drawn straight as a ponderosa pine, has had to be reconfigured with more branches leading here and there and, in some cases, apparently nowhere.

"When I went to medical school in 1963, human evolution looked like a ladder," Dr. Wood said. The ladder, he explained, stepped from monkey to modern human through a progression of intermediates, each slightly less apelike than the previous one.

But the fact that modern Homo sapiens is the only hominid living today is quite misleading, an exception to the rule dating only since the demise of Neanderthals some 30,000 years ago. Fossil hunters keep finding multiple species of hominids that overlapped in time, reflecting evolutionary diversity in response to new or changed circumstances. Not all of them could be direct ancestors of Homo sapiens. Some presumably were dead-end side branches.

So a tangled bush has now replaced a tree as the ascendant imagery of human evolution. Most scientists studying the newfound African skull think it lends strong support to hominid bushiness almost from the beginning.

That is one of several reasons Dr. Daniel E. Lieberman, a biological anthropologist at Harvard, called the African specimen "one of the greatest paleontological discoveries of the past 100 years."

The skull was uncovered in the desert of Chad by a French-led team under the direction of Dr. Michel Brunet of the University of Poitiers. Struck by the skull's unusual mix of apelike and evolved hominid features, the discoverers assigned it to an entirely new genus and species — Sahelanthropus tchadensis. It is more commonly called Toumai, meaning "hope of life" in the local language.

In announcing the discovery in the July 11 issue of the journal Nature, Dr. Brunet's group said the fossils — a cranium, two lower jaw fragments and several teeth — promised "to illuminate the earliest chapter in human evolutionary history."

The age, face and geography of the new specimen were all surprises.

About a million years older than any previously recognized hominid, Toumai lived close to the time that molecular biologists think was the earliest period in which the human lineage diverged from the chimpanzee branch. The next oldest hominid appears to be the 6-million-year-old Orrorin tugenensis, found two years ago in Kenya but not yet fully accepted by many scientists. After it is Ardipithecus ramidus, which probably lived 4.4 million to 5.8 million years ago in Ethiopia.

"A lot of interesting things were happening earlier than we previously knew," said Dr. Eric Delson, a paleontologist at the City University of New York and the American Museum of Natural History.

The most puzzling aspect of the new skull is that it seems to belong to two widely separated evolutionary periods. Its size indicates that Toumai had a brain comparable to that of a modern chimp, about 320 to 380 cubic centimeters. Yet the face is short and relatively flat, compared with the protruding faces of chimps and other early hominids. Indeed, it is more humanlike than the "Lucy" species, Australopithecus afarensis, which lived more than 3.2 million years ago.

"A hominid of this age," Dr. Wood wrote in Nature, "should certainly not have the face of a hominid less than one-third of its geological age."

Scientists suggest several possible explanations. Toumai could somehow be an ancestor of modern humans, or of gorillas or chimps. It could be a common ancestor of humans and chimps, before the divergence.

"But why restrict yourself to thinking this fossil has to belong to a lineage that leads to something modern?" Dr. Wood asked. "It's perfectly possible this belongs to a branch that's neither chimp nor human, but has become extinct."

Dr. Wood said the "lesson of history" is that fossil hunters are more likely to find something unrelated directly to living creatures — more side branches to tangle the evolutionary bush. So the picture of human genealogy gets more complex, not simpler.

A few scientists sound cautionary notes. Dr. Delson questioned whether the Toumai face was complete enough to justify interpretations of more highly evolved characteristics. One critic argued that the skull belonged to a gorilla, but that is disputed by scientists who have examined it.

Just as important perhaps is the fact that the Chad skull was found off the beaten path of hominid research. Until now, nearly every early hominid fossil has come from eastern Africa, mainly Ethiopia, Kenya and Tanzania, or from southern Africa. Finding something very old and different in central Africa should expand the hunt.

"In hindsight, we should have expected this," Dr. Lieberman said. "Africa is big and we weren't looking at all of Africa. This fossil is a wake-up call. It reminds us that we're missing large portions of the fossil record."

Although overshadowed by the news of Toumai, the well-preserved 1.75-million-year-old skull from Georgia was also full of surprises, in this case concerning a later chapter in the hominid story. It raised questions about the identity of the first hominids to be intercontinental travelers, who set in motion the migrations that would eventually lead to human occupation of the entire planet.

The discovery, reported in the July 5 issue of the journal Science, was made at the medieval town Dmanisi, 50 miles southwest of Tbilisi, the Georgian capital. Two years ago, scientists announced finding two other skulls at the same site, but the new one appears to be intriguingly different and a challenge to prevailing views.

Scientists have long been thought that the first hominid out-of-Africa migrants were Homo erectus, a species with large brains and a stature approaching human dimensions. The species was widely assumed to have stepped out in the world once they evolved their greater intelligence and longer legs and invented more advanced stone tools.

The first two Dmanisi skulls confirmed one part of the hypothesis. They bore a striking resemblance to the African version of H. erectus, sometimes called Homo ergaster. Their discovery was hailed as the most ancient undisputed hominid fossils outside Africa.

But the skulls were associated with more than 1,000 crudely chipped cobbles, simple choppers and scrapers, not the more finely shaped and versatile tools that would be introduced by H. erectus more than 100,000 years later. That undercut the accepted evolutionary explanation for the migrations.

The issue has become even more muddled with the discovery of the third skull by international paleontologists led by Dr. David Lordkipanidze of the Georgian State Museum in Tbilisi. It is about the same age and bears an overall resemblance to the other two skulls. But it is much smaller.

"These hominids are more primitive than we thought," Dr. Lordkipanidze said in an article in the current issue of National Geographic magazine. "We have a new puzzle."

To the discoverers, the skull has the canine teeth and face of Homo habilis, a small hominid with long apelike arms that evolved in Africa before H. erectus. And the size of its cranium suggests a substantially smaller brain than expected for H. erectus.

In their journal report, the discovery team estimated the cranial capacity of the new skull to be about 600 cubic centimeters, compared with about 780 and 650 c.c.'s for the other Dmanisis specimens. That is "near the mean" for H. habilis, they noted. Modern human braincases are about 1,400 cubic centimeters.

Dr. G. Philip Rightmire, a paleontologist at the State University of New York at Binghamton and a member of the discovery team, said that if the new skull had been found before the other two, it might have been identified as H. habilis.

Dr. Ian Tattersall, a specialist in human evolution at the natural history museum in New York City, said the specimen was "the first truly African-looking thing to come from outside Africa." More than anything else, he said, it resembles a 1.9-million-year-old Homo habilis skull from Kenya.

For the time being, however, the fossil is tentatively labeled Homo erectus, though it stretches the definition of that species. Scientists are pondering what lessons they can learn from it about the diversity of physical attributes within a single species.

Dr. Fred Smith, a paleontologist who has just become dean of arts and sciences at Loyola University in Chicago, agreed that his was a sensible approach, at least until more fossils turn up. Like other scientists, he doubted that two separate hominid species would have occupied the same habitat at roughly the same time. Marked variations within a species are not uncommon; brain size varies within living humans by abut 15 percent.

"The possibility of variations within a species should never be excluded," Dr. Smith said. "There's a tendency now for everybody to see three bumps on a fossil instead of two and immediately declare that to be another species."

Some discoverers of the Dmanisi skull speculated that these hominids might be descended from ancestors like H. habilis that had already left Africa. In that case, it could be argued that H. erectus itself evolved not in Africa but elsewhere from an ex-African species. If so, the early Homo genealogy would have to be drastically revised.

But it takes more than two or even three specimens to reach firm conclusions about the range of variations within a species. Still, Georgia is a good place to start. The three specimens found there represent the largest collection of individuals from any single site older than around 800,000 years.

"We have now a very rich collection, of three skulls and three jawbones, which gives us a chance to study very properly this question" of how to classify early hominids, Dr. Lordkipanidze said, and paleontologists are busy this summer looking for more skulls at Dmanisi.

"We badly want to know what the functional abilities of the first out-of-Africa migrants were," said Dr. Wood of George Washington University. "What could that animal do that animals that preceded it couldn't? What was the role of culture in this migration? Maybe other animals were leaving and the hominids simply followed."

All scholars of human prehistory eagerly await the next finds from Dmanisi, and in Chad. Perhaps they will help untangle some of the bushy branches of the human family tree to reveal the true ancestry of Homo sapiens.




TOPICS: Culture/Society; Extended News; Foreign Affairs; News/Current Events
KEYWORDS: black; crevolist; discovery; dmanisi; dna; evolution; gene; genealogy; georgia; godsgravesglyphs; history; homoerectus; homoerectusgeorgicus; human; man; mtdna; multiregionalism; oldowan; origin; origins; paleontologist; republicofgeorgia; science; sea; skull; theory
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To: Tribune7
You don't think Stalin's birth (and life) has influenced life on Earth?

Are you arguing as honestly as you know how?

301 posted on 08/14/2002 5:49:13 PM PDT by VadeRetro
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To: gore3000
You are correct, I was wrong. Now I understand my mistake.

Hah! You're not G3K!

302 posted on 08/14/2002 5:53:46 PM PDT by VadeRetro
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To: VadeRetro
Vade,

You got me flummoxed here. How about we start from scratch with revamped question.

303 posted on 08/14/2002 5:56:54 PM PDT by Tribune7
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To: BMCDA
"Religion is the opiate of the masses" but he was wrong when he assumed that this was a bad thing ;)
Of course this also reminds me of Voltaires bonmot:
If God did not exist, it would be necessary to invent him.

You do realize that your agreement to the above supports the contention of the Christians that religion is good and atheism is bad, don't you?

304 posted on 08/14/2002 5:57:18 PM PDT by gore3000
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To: VadeRetro
Freezing temperatures in Hell are being reported.
305 posted on 08/14/2002 5:57:39 PM PDT by PatrickHenry
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To: Tribune7
You got me flummoxed here. How about we start from scratch with revamped question.

Do you understand that the origin of the human species was over by the time of any historical human whosoever?

306 posted on 08/14/2002 5:58:56 PM PDT by VadeRetro
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To: Tribune7
Because it's more desirable. How do you find out? Well, just observe where most people in the world want to live if they could choose freely. I'd wager it's the West and there especially the U.S. (the happiness "sink" ;-D).
307 posted on 08/14/2002 6:01:27 PM PDT by BMCDA
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To: VadeRetro
You mean with Adam and Eve? :-)
308 posted on 08/14/2002 6:05:59 PM PDT by Tribune7
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To: Tribune7
And the same was true for S. J. Gould. He was a leftist and here I disagreed with him but that doesn't mean that I had to disagree with everything he said. And the same is true for Shaw and Russel and Einstein (who was also quite a leftie).
309 posted on 08/14/2002 6:07:17 PM PDT by BMCDA
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To: Tribune7
You mean with Adam and Eve? :-)

And Peter Pan and the Tooth Fairy, yes.

310 posted on 08/14/2002 6:08:44 PM PDT by VadeRetro
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To: VadeRetro
placemarker
311 posted on 08/14/2002 6:11:20 PM PDT by Junior
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To: BMCDA
But consider this: why should it be a goal to have a "stable society where the happiness of as many people as possible is as high as possible?" . . . . Because it's more desirable. How do you find out? Well, just observe where most people in the world want to live if they could choose freely. I'd wager it's the West and there especially the U.S. (the happiness "sink" ;-D)

You and I think that because we have been ingrained to think that. Saddam Hussein would disagree -- as would everybody who thinks they could be a Saddam. They would think the most desirable government is them ruling and us as slaves.

Now, we're right and Hussein, Stalin et al were/are wrong. But our understanding didn't occur by random chance in a vacuum.

Our nation is founded -- with premeditation on Christ's teachings.

Franklin and Jefferson -- who didn't believe in the Lord's divinity -- wanted his teachings established. Adams, Washington, Alexander Hamilton and Patrick Henry (should he be pinged?) were fairly traditional Christians and weren't going to disagree.

And because you and I are Americans guided by Christian values -- whether we believe that Jesus is God or not -- we think that our goal should be to have a "stable society where the happiness of as many people as possible is as high as possible."

312 posted on 08/14/2002 6:17:11 PM PDT by Tribune7
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To: gore3000
Only that religion can be useful sometimes. Especially for people who need the carrot and the stick in order to not run amok.

So if the only reason you don't kill, steal and rape is your belief in a god who punishes you if you commit the aforementioned and rewards you if you refrain from doing so, then I really hope you never lose your belief in this god and become an atheist.

The reason why I engage in discussions on this topic with other people here on FR is to show that a lack of belief in a god does not automatically make you a rapist, thief or even a murderer.

Regards

313 posted on 08/14/2002 6:17:18 PM PDT by BMCDA
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To: BMCDA
No, Shaw and Russell are in class by themselves. Einstein--who I admire -- and Gould -- who I don't -- weren't all that politcal.

Shaw and Russell were among the guiding plotters of the Fabian Socialists and hence responsible for disproportiona share the headaches we conservatives have suffered during the last century.

314 posted on 08/14/2002 6:21:04 PM PDT by Tribune7
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To: Tribune7
You don't have to use Saddam or Stalin as negative examples. If you go further back in time and regard European monarchies, you'll notice that they were also founded on Christ's teaching and that even officially, unlike the U.S.
They were officially recognized by the Christian churches (catholic, protestant and eastern orthodox) thus they really believed that it was the form of government that God wanted.

So it really seems that everyone tries to use the teachings of Christ (or any other god, prophet, etc.) to justify whatever he thinks is right.

315 posted on 08/14/2002 6:47:53 PM PDT by BMCDA
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To: Tribune7
Once again, so what? I don't have to agree with their views on economy in order to agree with their views on religion. I can separate the two.
316 posted on 08/14/2002 6:50:02 PM PDT by BMCDA
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To: BMCDA
If you go further back in time and regard European monarchies, you'll notice that they were also founded on Christ's teaching . . .

But they weren't founded on Christ's teachings. They used the Bible to justify maintaining their power -- divine right etc. -- but Europe's royal houses were founded on the acquistion of personal power.

317 posted on 08/14/2002 7:00:31 PM PDT by Tribune7
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To: FourtySeven
My question to you medved is this: Do you really believe the Earth orbited Saturn at one time? Or that humans are the result of genetic engineering? Or that the Grand Canyon is the result of lightning strike(s)?

The simplest case is the grand canyon. We're not talking about a "lightning strike" here; we're talking about an electrical discharge between this planet and some other cosmic body, a comet, asteroid, or another planet in prehistoric times. The fractal topography, the sinuous rills and infinite quantity of "tributaries" are precisely what you get running an arc welder to rocky ground. The material got vaporized and blasted off into space so that we don't find the huge pile of debris you'd expect out in the Colorado river delta.

There is no plausible case for the idea of the Colorado river carving that canyon out of stone. Real rivers which are 20 miles across are relatively shallow; you can wade out into the Amazon or the Volga quite a ways before you have to swim. The last thing in the world you'd ever expect to see walking up to the shore of something like the Volga would be a 2000' straight drop with sharp and pristine rocks in evidence everywhere you look and mesas which, had the whole fricking scene been that of a river, would have been 3000' below water, also with sharp and pristine rocks rather than being glassy smooth as you'd expect.

318 posted on 08/14/2002 7:01:55 PM PDT by medved
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To: BMCDA
Once again, so what? I don't have to agree with their views on economy in order to agree with their views on religion. I can separate the two.

I don't mean to imply otherwise. Forgive me if I did.

They are still the enemy, though. :-)

319 posted on 08/14/2002 7:02:31 PM PDT by Tribune7
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To: medved; FourtySeven
My question to you medved is this: Do you really believe the Earth orbited Saturn at one time? Or that humans are the result of genetic engineering? Or that the Grand Canyon is the result of lightning strike(s)?

Are humans the result of genetic engineering and/or re-engineering in past ages? I think that's the way you have to bet it.

Evolutionists are looking at the wrong end of the "lineup" or whatever you want to call it of hominid and human types. The problem is at the near end and not the far end.

Recent studies of neanderthal DNA turned up the result that neanderthal DNA is "about halfway between ours and that of a chimpanzee", and that there is no way we could interbreed with them or be descended from them via any process resembling evolution. That says that anybody wishing to believe that modern man evolved has to come up with some closer hominid, i.e. a plausible ancestor for modern man, and that the closer hominid would stand closer to us in both time and morphology than the neanderthal, and that his works and remains should be very easy to find, since neanderthal remains and works are all over the map. Of course, no such closer hominid exists; all other hominids are much further from us than the neanderthal.

An evolutionist could try to claim that we and the neanderthal both are descended from some more remote ancestor 200,000 years ago, but that would be like claiming that dogs couldn't be descended from wolves, and must therefore be descended from fish, i.e. the claim would be idiotic.

That leaves three possibilities: modern man was created from scratch very recently, was genetically re-engineered from the neanderthal, or was imported from elsewhere in the cosmos.

Aside from that conundrum, there is direct evidence of genetic engineering in past ages.

Henry Gee
Monday February 12, 2001
The Guardian

The potentially-poisonous Japanese fugu fish has achieved notoriety, at least among scientists who haven't eaten any, because it has a genome that can be best described as "concise". There is no "junk" DNA, no waste, no nonsense. You get exactly what it says on the tin. This makes its genome very easy to deal with in the laboratory: it is close to being the perfect genetic instruction set. Take all the genes you need to make an animal and no more, stir, and you'd get fugu. Now, most people would hardly rate the fugu fish as the acme of creation. If it were, it would be eating us, and not the other way round. But here is a paradox. The human genome probably does not contain significantly more genes than the fugu fish. What sets it apart is - and there is no more succinct way to put this - rubbish.

The human genome is more than 95% rubbish. Fewer than 5% of the 3.2bn As, Cs, Gs and Ts that make up the human genome are actually found in genes. It is more litter-strewn than any genome completely sequenced so far. It is believed to contain just under 31,780 genes, only about half as many again as found in the simple roundworm Caenorhabditis elegans (19,099 genes): yet in terms of bulk DNA content, the human genome is almost 30 times the size.A lot is just rubbish, plain and simple. But at least half the genome is rubbish of a special kind - transposable elements. These are small segments of DNA that show signs of having once been the genomes of independent entities. Although rather small, they often contain sequences that signal cellular machinery to transcribe them (that is, to switch them on). They may also contain genetic instructions for enzymes whose function is to make copies and insert the copies elsewhere in the genome. These transposable elements litter the human genome in their hundreds of thousands. Many contain genes for an enzyme called reverse transcriptase - essential for a transposable element to integrate itself into the host DNA.

The chilling part is that reverse transcriptase is a key feature of retroviruses such as HIV-1, the human immunodeficiency virus. Much of the genome itself - at least half its bulk - may have consisted of DNA that started out, perhaps millions of years ago, as independent viruses or virus-like entities. To make matters worse, hundreds of genes, containing instructions for at least 223 proteins, seem to have been imported directly from bacteria. Some are responsible for features of human metabolism otherwise hard to explain away as quirks of evolution - such as our ability to metabolise psychotropic drugs. Thus, monoamine oxidase is involved in metabolising alcohol.

If the import of bacterial genes for novel purposes (such as drug resistance) sounds disturbing and familiar, it should - this is precisely the thrust of much research into the genetic modification of organisms in agriculture or biotechnology.

So natural-born human beings are, indeed, genetically modified. Self-respecting eco-warriors should never let their children marry a human being, in case the population at large gets contaminated with exotic genes!One of the most common transposable elements in the human genome is called Alu - the genome is riddled with it. What the draft genome now shows quite clearly is that copies of Alu tend to cluster where there are genes. The density of genes in the genome varies, and where there are more genes, there are more copies of Alu. Nobody knows why, yet it is consistent with the idea that Alu has a positive benefit for genomes. To be extremely speculative, it could be that a host of very similar looking Alu sequences in gene-rich regions could facilitate the kind of gene-shuffling that peps up natural genetic variation, and with that, evolution. This ties in with the fact that human genes are, more than most, fragmented into a series of many exons, separated by small sections of rubbish called introns - rather like segments of a TV programme being punctuated by commercials.

The gene for the protein titin, for example, is divided into a record-breaking 178 exons, all of which must be patched together by the gene-reading machinery before the finished protein can be assembled. This fragmentation allows for alternative versions of proteins to be built from the same information, by shuffling exons around. Genomes with less fragmented genes may have a similar number of overall genes - but a smaller palette of ways to use this information. Transposable elements might have helped unlock the potential in the human genome, and could even have contributed to the fragmentation of genes in the first place (some introns are transposable elements by another name). This, at root, may explain why human beings are far more complex than roundworms or fruit flies. If it were not for trashy transposable elements such as Alu, it might have been more difficult to shuffle genes and parts of genes, creating alternative ways of reading the "same" genes. It is true that the human genome is mostly rubbish, but it explains what we are, and why we are who we are, and not lying on the slab in a sushi bar.

• Deep Time by Henry Gee will be published shortly in paperback by Fourth Estate. He is a senior editor of Nature. Related articles

320 posted on 08/14/2002 7:07:28 PM PDT by medved
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