Sir

Andrew Whiten and colleagues' study of group learning, “Conformity to cultural norms of tool use in chimpanzees” (Nature 437, 737–740; 2005), is intended to show evolutionary continuity between humans and other animals, but the authors directly make that claim only for conformity.

Jacqueline Zupp, in Correspondence (Nature 437, 1089; 200510.1038/4371089d), says she finds it absurd to believe that human culture and society developed without precedent among animals and adds that we “now have evidence for animal cultures, as reported in the pages of this journal”.

The experiment by Whiten and colleagues is well conceived and executed, and is entirely convincing on its own terms. But continuity between learning to open a latch that is already there, and creating, say, The Iliad or the pythagorean theorem, is not obvious. Are we to value the proof above what is being proved?

The continuity of the human mind with the animal mind is the most important question in human evolution, so we want to get it right. But in our rush to triumph, we should not allow our conclusions to be driven tacitly by hints and implications and the use of emotional vocabulary in a way that would never be tolerated in, say, chemistry or mathematics. Like Zupp, I am an evolutionist, and I do not wish to see our science paint itself into a corner from which the only escape leads through a gauntlet of public embarrassment.