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Title: Ethiopian fossils link humans to 4.4 million-year-old apelike creatures, researchers say
Source:
San Francisco Gate
URL Source: http://sfgate.com/cgi-bin/article.c ... c/a/2006/04/13/MNGMII8GLK1.DTL
Published: Apr 13, 2006
Author: - David Perlman, Chronicle Science Edito
Post Date: 2006-04-13 15:59:16 by Zipporah
Keywords: None
Views: 44
Comments: 5
EARLIER ANCESTORS Thursday, April 13, 2006 Fossil hunters scouring Ethiopia's harsh and rocky Afar desert have uncovered fresh evidence linking our human ancestors of 3.5 million years ago with more primitive apelike forebears who lived a million years earlier and had not yet emerged from woodland habitats. The scattering of fossil teeth and bones "represent unambiguous evidence for human evolution," says Tim White, a UC Berkeley paleoanthropologist and leader of the international Middle Awash research project. Some of the fossils were unearthed as recently as December while the scientists were exploring sedimentary rock layers around the tiny villages of Aramis and Asa Issie, near the muddy Awash River in the rift region some 140 miles northeast of Addis Ababa. Within those rocks, the scientists report, they found fossils from three early species of mankind's ancestors that apparently succeeded each other during less than a million years of evolution. White and his team, including Ethiopia-born geologist Giday WoldeGabriel of the Los Alamos National Laboratory in New Mexico and paleoanthropologist Berhane Asfaw, director of the Rift Valley Research Service in Addis Ababa, along with 19 other colleagues, are publishing a detailed report on their findings today in the journal Nature. The early human ancestors whose traces the team found are known as hominids. They include the genus called Australopithecus that existed throughout eastern Africa as early as 4.2 million years ago. Their forebears -- possibly direct ancestors of Australopithecus -- are the Ardipithecus genus, which ranged across the entire continent as early as 6 million years ago. Ardipithecus became extinct about the time that the earliest of seven known species of Australopithecus emerged, the fossil record indicates. The Australopithecus species are now considered the ancestors of a line that ultimately evolved into Homo sapiens -- modern humans. Most famous among the Australopithecus species is "Lucy," the 31/2-foot-tall female who lived about 3.18 million years ago and whose scientific name is Au. afarensis. Her skeleton was discovered in 1974 by Donald Johanson at a site 50 miles north of where the Berkeley team's most recent discoveries were made. (Anthropologists traditionally use initials for genus names -- Au. for Australopithecus and Ar. for Ardipithecus.) The new-found fossils reported by the Berkeley team represent an earlier ancestral species named Au. anamensis and were much older than Lucy but still short with small brains and large heavily enameled teeth capable of chewing rough roots and tubers. They lived about 4.2 million years ago, the scientists said. The first anamensis fossils in the Awash area were discovered in 1994, by Alemayehu Asfaw, a veteran Ethiopian fossil hunter. Before then, the species was known only from fossils in northern Kenya, about 500 miles southwest -- which indicates the extent of the creatures' habitat, White said. Since then, the Berkeley team has found many more fossilized remains of species from both the Australopithecus and Ardipithecus lineages. Fossils of the Ardipithecus line, named Ar. ramidus, were discovered in 1992 by White and his team in the Awash River area, and only in December, while The Chronicle was with the expedition, the fossil hunters found several ramidus teeth and a jaw fragment near the village of Asa Issie, one of many homes of the region's pastoral Afar tribe. The Afar villages of Aramis and Asa Issie are only a few miles apart, and in sedimentary rock formations of the parched desert region the Berkeley team also found fossil teeth and bone fragments from Au. anamensis, at 4.1 million years old, lying above Ar. ramidus fossils at 4.4 million years old. And above both those fossils lay remains of the younger Lucy afarensis species at 3.4 million years old. This was the first time all three species "have been found to be time-successive in a single place," White says. And it provides strong evidence for "the evolutionary transition from Ardipithecus to Australopithecus," he said. To explain this kind of progression, he and his colleagues propose two hypotheses: Australopithecus may have evolved directly and rapidly from Ar. ramidus. Or the ramidus creatures may have continued living alongside their Australopithecus descendants for hundreds of thousands of years before becoming extinct. WoldeGabriel said petrified wood and the fossil bones of monkeys, kudus and other horned mammals among the hominids all indicate that the region was heavily forested during the time that Ardipithecus and the early Australopithecus species existed. But other animals, such as the oryx, a species of small antelope, existed much later as the forest environment changed to open savannah and later Australopithecus species adapted to it, Asfaw said in an e-mail. "A big part of the life history of the early hominids was in the forest. As we can see it now, at least 3 million years of hominid evolution was in the closed woodlands, so hominids started walking upright in the forest, not in the open." As for the fossil hunters, scraping the sand and rocks of the Afar region requires tireless backs, sharp eyes and tough hands, and some of the most significant hominid finds by the expedition came during this winter's field season. Among those discoveries were a canine tooth found by Ferhat Kaya from the University of Ankara in Turkey; a single molar and a tiny tooth fragment unearthed by Kampiro Kayranto, an Ethiopian veteran of five seasons with the Middle Awash team; and a molar fragment and the toothless fragment of a lower jaw spotted by Moges Mekonnen, an Ethiopian field cook assistant with the expedition who has been trained as a skilled fossil collector. E-mail David Perlman at dperlman@sfchronicle.com. Page A - 2
EARLIER ANCESTORS / Ethiopian fossils link humans to 4.4 million-year-old apelike creatures, researchers say Scientists found teeth, upper jaws, hand and foot bones and fragments of other bones of the ancient species in the Afar desert. Brill Atlanta photo by David L. Brill via Associated Press
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#1. To: Zipporah (#0)
If they could see what they've become, they'd run and hide.
.. I know.. :(
Nah, that's just my mother in law.
"I woke up in the CRAZY HOUSE."
ROFLMAO!!! Dried up old hag huh? ;P
there's something about the phrase "4.4 million year old ape-like creature" that rings a bell.
"I woke up in the CRAZY HOUSE."
I've already said too much.
#2. To: MUDDOG (#1)
If they could see what they've become, they'd run and hide.
#3. To: Zipporah (#0)
#4. To: mehitable (#3)
Nah, that's just my mother in law.
#5. To: Zipporah (#4)
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