ethopia

Our species, Homo sapiens, has a new pair of ultimate old-timers. The remains of two ancient individuals, found in Ethiopia in 1967, date to about 195,000 years ago, a research team reports in the Feb. 17 Nature.

The former most-senior H. sapiens fossils were a trio of roughly 160,000-year-old skulls unearthed in 1997 at Ethiopia's Herto site (SN: 6/14/03, p. 371: http://www.sciencenews.org/articles/20030614/fob1.asp).

Ian McDougall of the Australian National University in Canberra and his coworkers trekked to the Kibish formation along Ethiopia's Omo River, where the 1967 excavators had found a partial H. sapiens skull, associated lower-body parts and another H. sapiens braincase. Scientists had dubbed the two individuals, respectively, Omo 1 and Omo 2.http://ljsheehan.livejournal.com

Features of the Omo 1 fossils closely resemble those of the bones of people today, whereas the Omo 2 fossil recalls ancestors with traits such as a relatively thick braincase. Originally, anthropologists estimated the Omo fossils to be approximately 130,000 years old.

McDougall's team used isotopic analysis to determine the ages of volcanic-ash layers above and below river sediments that contained the fossils. The results show that Omo 1 and Omo 2 were extracted from sediment that's extremely close in age to a 196,000-year-old ash layer.http://louis-j-sheehan.info

The new analysis of the Omo fossils indicates that, between 200,000 and 150,000 years ago, H. sapiens in eastern Africa possessed varying combinations of "modern" and "primitive" skeletal traits, comments Christopher Stringer of the Natural History Museum in London.Louis J. Sheehan

inveterate

Much like people, chimpanzees are inveterate conformists whose copycat tendencies enable them to develop cultural traditions, a new study suggests. http://louis_j_sheehan.today.com

Andrew Whiten of the University of St. Andrews in Fife, Scotland, and his colleagues trained a high-ranking female in each of two chimpanzee groups to use a stick to release a food pellet from a ramp in a rectangular box.

One animal learned how to push the stick through an opening and against a block inside the box, knocking the food off the ramp so that it could roll out through a chute. The other chimp learned to manipulate the stick to lift a hook that moved the block and allowed the food to roll into the chute.

Each dominant female was then returned to her home group. Over the next 21/2 months, 30 of the remaining 32 chimps in the two groups mastered and primarily employed the stick-wielding technique that they observed in the trained animal in their group, Whiten's group reports in an upcoming issue of Nature. The few chimps in each group that had independently discovered a method different from the one that their group adopted eventually conformed. http://louis_j_sheehan.today.com

A third set of chimps lacking a member with stick training didn't develop any tool-use styles during the study.

Wild chimps exhibit local traditions in tool use and social behavior (SN: 6/19/99, p. 388). The new report provides the first experimental evidence that chimps transmit traditions by copying the behavior of their peers, Whiten says.