| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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Life on the Edge Found Links
Once there was only one link missing between humans and apes. Now there are dozens. With each newly unearthed fossil, the evolution of man becomes more complicated. With each new discovery there is another gap to fill. And, over the last 40 years, there have been many discoveries. Over the last 40 days there have been many discoveries. Here we are dealing with subjects that are variously thousands and millions of years old, and yet you can't open the morning paper without reading about yet another find. April 23, Science magazine: A team, co-led by the ubiquitous paleoanthropologist Tim White from the University of California at Berkeley, discovers a possible missing link dating back 2.5 million years ago to that misty period when australopithecines-bipedal apes-gave way to the genus Homo-characterized by changes to the jaw and skull, particularly a larger brain cavity. We won't know for a while whether the newly named Australopithecus garhi is a direct ancestor of the only living bipedal ape species. But perhaps not such a long while if the analytic techniques which Adrienne Zihlman and Jerold Lowenstein explain in "From Eternity to Here" continue to be refined at their current pace. If an article in Nature, May 6, is correct, tool making was already quite sophisticated by the time A. garhi was alive, over half a million years earlier than previous evidence had suggested. A team, also working in Africa's Rift Valley, reconstructed about 60 original stones from more than 2,000 discarded flakes. As Nina Jablonski points out in "Upright Characters," the ability to visualize a useful tool within a stone requires a level of abstract thought not generally evident today, in any species other than our own. Jump ahead 2.475 million years, give or take a hundred thousand, and we find a young boy, about four years old, being buried into a shallow grave in Portugal. Last April 25, The New York Times reported on the discovery of the grave, dated to nearly 25,000 years ago, 5,000 years after Homo neanderthalensis is known to have gone extinct. But what is unusual about the boy, according to Erik Trinkaus, a paleoanthropologist at Washington University in St. Louis, is that, while his facial characteristics were those of a modern human, his limb proportions resembled a Neandertal. In other words, a hybrid. According to Jerold Lowenstein in his Counterpoints in Science column ("The Other People"), the DNA evidence found elsewhere shows, pretty conclusively, that such a merger never happened. About the time the Neandertals were disappearing, a group of Homo sapiens, having recently evolved a sense of aesthetics (see Blake Edgar's "The Symbol and the Spear"), took advantage of their new talents in a cave just west of the French Alps. A subsequent rock fall sealed off the entrance to the cave, and not until four years ago did a group of explorers stumble on this creative cornucopia. Immediately aware of the significance of Grotte Chauvet, the French Ministry of Culture instituted strict rules for its exploration. Only scientists can enter, and precious few of them. Margaret Conkey, professor of anthropology at the University of California at Berkeley and an Academy Fellow, was recently allowed access, the first American among the chosen. Her account, "Inside Grotte Chauvet," describes the experience. Fast forward about 20,000 years and through 240º of longitude. Someone, most accounts suggest, has just discovered the New World. Where accounts differ is on the mode of the adventurer's transport. Tabitha M. Powledge in "The Riddle of the Ancient Mariners," points out that rather than hoofing it through terrain left soggy and barren by the what, no one knows-they crossed the Bering Strait and soon headed south to warmer climes. Just check the San Francisco Chronicle, April 12, where we learn that a body found 40 years ago on Santa Rosa Island in the Channel Islands has now been dated to 13,000 years ago and may be the oldest skeleton ever found in this hemisphere. Keith K. Howell is Editor of California Wild. |
Summer 1999
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