Monday, September 6, 2010

Chimpanzees, cabbages, and DNA

For years, I've been irked by the assertion that appears with tedious certainty in every popular article about animal intelligence: chimpanzees, we will be dramatically informed at some point, share 98 or 95 or 98.6 percent of their DNA in common with us — the implication being that they therefore must be 98 or 95 or 98.6 percent just like us in cognitive ability.

Recently re-reading Clive Wynne's book Do Animals Think?, I came across a good explanation of why this is a meaningless yardstick. By the same methodology, one would conclude that all humans are 99.9999 percent alike in brainpower — a conclusion that anyone who has tuned in to talk radio would find hard to swallow. And for that matter a completely random collection of DNA base pairs ought to possess 25 percent of our smarts.

I hope this chart I made (click to enlarge) will clear things up:

Stephen Budiansky