Homo habilis Contemporary with Homo erectus

first_imgHomo habilis couldn’t have been the ancestor of Homo erectus, because they lived side by side.  This has been all over the news since it was announced in Nature yesterday: see the Times UK, PhysOrg, the BBC News, Reuters Africa, National Geographic, and MSNBC News, which says the new discovery paints a “messy” view of human origins: “Surprising fossils dug up in Africa are creating messy kinks in the iconic straight line of human evolution with its knuckle-dragging ape and briefcase-carrying man.”    OK, what happened?  Meave Leakey found a small female Homo erectus skull in Kenya that dates from the same period as Homo habilis, or “handy man,” long thought to have been a predecessor:In 2000 Leakey found an old H. erectus complete skull within walking distance of an upper jaw of the H. habilis, and both dated from the same general time period.  That makes it unlikely that H. erectus evolved from H. habilis, researchers said.    It’s 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….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.    But this should not cast evolutionary science into doubt, the article A.P. article was quick to point out: “All the changes to human evolutionary thought should not be considered a weakness in the theory of evolution, [Bill] Kimbel [Arizona State] said.  Rather, those are the predictable results of getting more evidence, asking smarter questions and forming better theories, he said.”    Yet it is hard to see how this helps the evolutionary story of progress between apes and humans.  This upset is similar, Kimbel said, to the revised story of Neanderthals, which also used to be considered human ancestors.  This effectively removes Homo habilis from consideration as an ancestor, leaving a gap where paleoanthropologists thought they had a link.  National Geographic speculated that the two hominid forms might have originated “two and three million years ago, which is a well-known gap in the fossil record.  The evidence for human evolution, therefore, has been reduced, not just messed up.    Although the skull was found in 2000, it often takes years for a research team to clean, date, and document the find.  Another claim from the announcement is that apparently males were larger than females (sexual dimorphism), but see commentary and picture from the 08/02/2007 entry about the flaw of drawing conclusions from limited samples.  Leakey and team believe the two forms lived contemporaneously and in proximity, as do chimpanzees and gorillas, for half a million years.    Ann Gibbons wrote in Science2 the next day about this find.  She noted that the blurring of distinctions between H. habilis and H. erectus makes ripples with another famous fossil, too: Homo ergaster:The skull also shows features that had previously been seen only in Asian fossils of H. erectus, such as a keeling (or ridge) on its frontal and parietal bones.  These traits had persuaded a growing number of researchers in recent years to split the fossils of H. erectus into two species, with H. erectus from Asia and H. ergaster from Africa.  But the skull’s mix of traits shows H. erectus cannot be “easily divided between two species from Africa and Asia,” says Spoor.  Kimbel and Arizona State graduate student Claire Terhune reached a similar conclusion after studying the temporal bones of 15 H. erectus skulls, in a paper published in the July issue of the Journal of Human Evolution.    Others who have championed H. ergaster are taking note.  “The new cranium blurs the distinction between H. erectus and H. ergaster,” says Wood.  “I am not willing to sell my shares in H. ergaster just yet, but I am not relying on them for my retirement!”1Leakey et al, “Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya,” Nature 448, 688-691 (9 August 2007) | doi:10.1038/nature05986.2Ann Gibbons, “New Fossils Challenge Line of Descent in Human Family Tree,” Science, 10 August 2007: Vol. 317. no. 5839, p. 733, DOI: 10.1126/science.317.5839.733.These people do not know who begat whom, and they can’t tell dates with any credibility; they keep losing links into gaps and moving things around, yet they expect us to believe they are the Masters of Enlightenment when telling us where we came from.    It’s important to remember that the bones aren’t talking.  Data don’t just jump up into a scientist’s hands and explain themselves.  Instead, picture a group of scientists at a large, blank game board, with a few fossils as game pieces, but no instructions.  They approach the game with a mental picture of how the game should be played and where the pieces go, but they are free to move them around.  Depending on how committed they are to their mental picture, they can compromise here or there and keep the picture intact.  The compromises make the game confusing and even chaotic at times.  Still, the commitment to the mental picture is paramount: it was carefully selected to conform to the Official Myth of the Culture.    We spectators might look with bewilderment at how they can keep playing such a confusing game, but, as outsiders, we are not permitted by the ruling elite to have an opinion, or to holler in suggestions to them.  They are all sworn to keep a straight face and maintain the appearance that everything is under control and that progress is being made.    Appearances are not realities, however.  If the mental picture is incorrect, the chaos is real.  Don’t be distracted by the elaborate canopy the game players have erected over their board, and all the concession stands, reporters and public announcements that “they’re getting warmer” and the latest find “sheds new light on evolution.”  It’s all just a sport with no necessary connection to reality.    The picture on the game board could be totally different, with a much better fit of the pieces.  No matter; if such a picture has been disqualified by an arbitrary consensus of the players, it will never be found, but the players will get to keep their jobs.  After all, a complex game with lots of twists and turns is more fun than a linear one.  And horrors, being told what the picture was supposed to be would spoil the party.(Visited 63 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img

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