Genes, not environment, make some chimps smarter

Just like humans, some chimpanzees are smarter than others, and about half of that variation in intelligence depends on the genes that individuals carry and pass on from one generation to the next, says a study.

Genetic differences are key to understanding the cognitive abilities of primates and their evolution over time, the findings showed.

"As is the case in humans, genes matter when it comes to cognitive abilities in chimpanzees," said William Hopkins of Yerkes National Primate Research Center in Emory University in the US.

"It does not mean that they are the only factor determining cognitive abilities, but they cannot be ignored," Hopkin added.

The new study found no effect of either sex or rearing history on the cognitive skills of chimpanzees.

That is, chimpanzees raised by human caretakers performed no better on cognitive tests delivered to them by humans than did individuals raised by their chimpanzee mothers.

The new study included data on the cognitive abilities of 99 chimpanzees in all, from age nine to 54. The researchers' analysis found that about 50 percent of the variation in the chimps' performance on a series of standardised cognitive tests could be attributed to genetic factors.

The study appeared in the journal Current Biology.