Saturday, 6 September 2008
Sahelanthropus: Fracas Over the Age of Purpoted Human Ancestor
The lower branches of this tree are in danger.
In 2001 a nearly complete skull was found in the Chadian desert. Called Toumai or Sahelanthropus tchadensis, it was announced to be a 7 million year old human ancestor. However, some critics refused to believe that the fossil had anything to do with human ancestry. Due to the small size of the skull, they calculated that Toumai could not be taller than 120 centimeters (four feet) and would thus be a chimpanzee. Recently, Physorg.Com. reported on the dispute that is still brewing over this skull.
French paleontologist Michael Brunei of the College de France continues to maintain that Toumai represented the stage when chimpanzees and hominids had just diverged from a common ancestor.
Recently, the Proceedings of the National Academy of Sciences published a study, confirming the age of the soil in which the fossil was found at between 6.8 million and 7. 2 million years.
The finding seemed to verify professor Brunei’s view. However, Alain Beauvilain of the University of Paris has challenged the date. Beauvilain was the man who found the skull. He recently told AFP that contrary to what Brunei had asserted, the cranium was found above the ground in loose sand. Commenting on the find in the South African Journal of Science, he added that the skull was encrusted with a blue ferruginous or iron-based mineral. This indicated that it had weathered in the desert conditions above the ground. Moreover, wind or erosion could well have shifted both the ground around the skull and the skull itself, making the date of 7 million years unreliable.
In the evolutionary paradigm, views on human origins seem to be almost as shifting as the Chadian desert sands in which Toumai was found. Radiometric dating does not fare much better.“Bad” dates are not as uncommon as is generally supposed as it is practically impossible to control all factors involved in the dating. It thus seems that it is time to say farewell to Sahelanthropus tchadensis.
Physorg. Com. 2008. Finder of key hominid fossil disputes 7-million-year dating. (1 September). http://www.physorg.com/news139493724.html