Posted on 09/18/2007 8:47:54 AM PDT by SirLinksalot
Surprising research based on two African fossils suggests our family tree is more like a wayward bush with stubby branches, challenging what had been common thinking on how early humans evolved.
The discovery by Meave Leakey, a member of a famous family of paleontologists, shows that two species of early human ancestors lived at the same time in Kenya. That pokes holes in the chief theory of man's early evolution — that one of those species evolved from the other.
And it further discredits that iconic illustration of human evolution that begins with a knuckle-dragging ape and ends with a briefcase-carrying man.
The old theory is that the first and oldest species in our family tree, Homo habilis, evolved into Homo erectus, which then became human, Homo sapiens. But Leakey's find suggests those two earlier species lived side-by-side about 1.5 million years ago in parts of Kenya for at least half a million years. She and her research colleagues report the discovery in a paper published in Thursday's journal Nature.
The paper is based on fossilized bones found in 2000. The complete skull of Homo erectus was found within walking distance of an upper jaw of Homo habilis, and both dated from the same general time period. That makes it unlikely that Homo erectus evolved from Homo habilis, researchers said.
It is the equivalent of finding that your grandmother and great-grandmother were sisters rather than mother-daughter, said study co-author Fred Spoor, a professor of evolutionary anatomy at the University College in London.
The two species lived near each other, but probably did not interact, each having its own "ecological niche," Spoor said. Homo habilis was likely more vegetarian while Homo erectus ate some meat, he said. Like chimps and apes, "they'd just avoid each other, they don't feel comfortable in each other's company," he said.
There remains some still-undiscovered common ancestor that probably lived 2 million to 3 million years ago, a time that has not left much fossil record, Spoor said.
Overall what it paints for human evolution is a "chaotic kind of looking evolutionary tree rather than this heroic march that you see with the cartoons of an early ancestor evolving into some intermediate and eventually unto us," Spoor said in a phone interview from a field office of the Koobi Fora Research Project in northern Kenya.
That old evolutionary cartoon, while popular with the general public, is just too simple and keeps getting revised, said Bill Kimbel, who praised the latest findings. He is science director of the Institute of Human Origins at Arizona State University and was not part of the Leakey team.
"The more we know, the more complex the story gets," he said. Scientists used to think Homo sapiens evolved from Neanderthals, he said. But now we know that both species lived during the same time period and that we did not come from Neanderthals.
Now a similar discovery applies further back in time.
For the past few years there has been growing doubt and debate about whether Homo habilis evolved into Homo erectus. One of the major proponents of the more linear, or ladder-like evolution that this evidence weakens, called Leakey's findings important, but he wasn't ready to concede defeat.
Dr. Bernard Wood, a surgeon-turned-professor of human origins at George Washington University, said in an e-mail Wednesday that "this is only a skirmish in the protracted 'war' between the people who like a bushy interpretation and those who like a more ladder-like interpretation of early human evolution."
Leakey's team spent seven years analyzing the fossils before announcing it was time to redraw the family tree — and rethink other ideas about human evolutionary history. That's especially true of most immediate ancestor, Homo erectus.
Because the Homo erectus skull Leakey recovered was much smaller than others, scientists had to first prove that it was erectus and not another species nor a genetic freak. The jaw, probably from an 18- or 19-year-old female, was adult and showed no signs of malformation or genetic mutations, Spoor said. The scientists also know it is not Homo habilis from several distinct features on the jaw.
That caused researchers to re-examine the 30 other erectus skulls they have and the dozens of partial fossils. They realized that the females of that species are much smaller than the males — something different from modern man, but similar to other animals, said study co-author Susan Anton, a New York University anthropologist. Scientists hadn't looked carefully enough before to see that there was a distinct difference in males and females.
Difference in size between males and females seem to be related to monogamy, the researchers said. Primates that have same-sized males and females, such as gibbons, tend to be more monogamous. Species that are not monogamous, such as gorillas and baboons, have much bigger males.
This suggests that our ancestor Homo erectus reproduced with multiple partners.
The Homo habilis jaw was dated at 1.44 million years ago. That is the youngest ever found from a species that scientists originally figured died off somewhere between 1.7 and 2 million years ago, Spoor said. It enabled scientists to say that Homo erectus and Homo habilis lived at the same time.
All the changes to human evolutionary thought should not be considered a weakness in the theory of evolution, Kimbel said. Rather, those are the predictable results of getting more evidence, asking smarter questions and forming better theories, he said.
I’m just wondering which of the branches were specified.
Argumentum ad nauseam is not particularly effective.
In the book “The Beak of the Finch”, one species of bird was believed to have evolved from another (I think a small beaked bird gave rise to a species with a larger beak, better able to handle a certain hard seed). Both species coexist, and the numbers of the different birds fluctuates back and forth. They can interbreed, yielding a range of offspring with varying beak size.
Why does the possibility of two different human species on Earth at the same time disprove “evolution”?
Interesting.
Waiting for the (somewhat off-topic) fireworks to start!
lol!
Somewhere buried in this article, there must be information about where these scientists converted to ID/Creationsts, somewhere.
Well that's convenient. Posit that there must be an ancestor, but make it clear that it's going to be hard to find.
"The more we know, the more complex the story gets," he said. Scientists used to think Homo sapiens evolved from Neanderthals, he said. But now we know that both species lived during the same time period and that we did not come from Neanderthals. Now a similar discovery applies further back in time.
Reminds me of a dike that's springing leaks all over the place. Evolutionists keep trying to plug them up but they keep running out of fingers.
“The evolutionists like the antiwar crowd and the global warming nuts wont let a little thing like facts get in the way of their religion.”
Exactly! These fools will do whatever they have to, including believing in something like evolution which there are no FACTS for to avoid facing real truth of the Bible, because the evolution religion doesn’t have morals. Gays, lesbians and other deviants are what keep this junk in our schools.
It doesn’t “disprove evolution”, and that’s NOT what they’re saying. They’re saying it disproves a certain theory within evolution - that of man’s descent.
But generally you’re correct; I don’t know why 2 species coexisting means that 1 could not possibly have originated from the other.
I’m just wondering which of the branches were specified.
I wouldn’t say that. Many, many evolutionists are conservative from what I see. Which largely makes sense, because if you think scientists are “thinkers” rather than “emoters”, conservatives tend to go more on thinking than mindless emoting.
“How can America evolve from England and there still be English walking around at the same time? It’s amazing to ponder how dumb evolution deniers can get.”
I don’t think it’s dumb.
We don’t believe that Americans “naturally selected” themselves out of England to improve their chances of physical survival. We don’t believe any physical changes occurred. That’s like gazelles moving from one plain to another for better grass. It’s not evolution.
Englishmen and Americans are the same species! To suggest otherwise is sort of dumb, if you ask me.
If you believe, for instance, that lizards evolved from fish because to continue to be a fish was tenuous - the water was getting too hot, or the food supply was running out, or what have you - then of course you would wonder, why are there still fish in countless varieties and huge abundance all over the world? Obviously there was no huge overwhelming “need” to develop air breathing lungs, etc.
Want to really watch their head explode? Ask them why we have a fossil record for plants and animals that existed only hundreds of millions of years ago, before the presence of man, and how that fits into a 6,000 year timeline...
They'll accept fossils when they think it can "disprove evolution" like here, but what about when it challenges the supposed timeline of the Bible?
This is an implausible statement even with "probably" as a qualifier. Wildebeast and lion each has its own "ecological nich," yet certainly interact.
Why are you connecting this find and theory with “evolution-deniers”?
These people are CLEARLY NOT evolution deniers.
Bad tie-in.
Why did you have to do that?
LOL!!
Huh? How do they interact, besides “chasing and killing”?
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