Chimpanzee found to be closest to human

Press, 26 July 1984, Page 11

Chimpanzee found to be closest to human

NZPA-AP Nairobi A comparison of two chemicals found in the blood of humans and other primates shows that the chimpanzee is mankind’s closest relative, a United States scientist has told an international conference of experts. The finding, which contradicts earlier claims that the gorilla or orang-utang ranks second, could help resolve arguments ranging from evolution to human behaviour, Dr Jerold Lowenstein said. Dr Lowenstein, professor of medicine at the University of California in San Francisco, spoke to 400 scientists at the tenth Congress of the International Primatological Society. He said that previous research on other chemicals indicated that mankind is closely related to both the gorilla and the chimpanzee, but those tests were not

sophisticated enough to say which was closer. Dr Lowenstein said he is 90 per cent certain that humans and chimps had a common ancestor who lived as recently as 4.5 million years ago. Gorillas probably started diverging from the common , ancestor one million years earlier. His conclusions come from unpublished studies comparing albumin and transferrin — found in the blood of most vertebrates, including humans, chimps, and gorillas. He used radioactive tracers to make more sensitive comparisons than before. Dr Lowenstein said two recently published studies by other researchers support his theory, although an article published this year in “Nature” magazine argues that the orang-utang might be mankind’s closest relative. Dr Lowenstein said the

“Nature” article was based on a comparison of anatomical features, which is not as precise as comparisons of genes and chemicals.

The new results could settle some outstanding controversies, Dr Lowenstein said. For example, the relationship of humans, chimpanzees and gorillas traced by Dr Lowenstein would mean that mankind’s ancestors probably walked on their knuckles like presentday chimps and gorillas.

In addition, it could mean that chimps would be the best animal to use as a model for theorising about what early humans were like.

A closer study of chimp behaviour could shed light on present-day human behaviour, he said. Behavioural psychologists already make extensive use of chimps for such studies.