Sir

William Abler, in Correspondence (“Evidence of group learning does not add up to culture” Nature 438, 422; 200510.1038/438422b), takes issue with Jacqueline Zupp's assertion, also in Correspondence (“Concern at animal research should not be dismissed” Nature 437, 1089; 200510.1038/4371089d), that “we now have evidence for animal cultures”.

Two points relevant to Abler's concern deserve emphasis in relation to the now-extensive literature on animal traditions, in which terms such as ‘culture’, ‘cultural transmission’ and ‘cultural evolution’ are routinely applied not to only to primates but also to taxa as diverse as birds and fish — references to the ‘cultural transmission of birdsong’, for example, have been familiar for decades.

First, many biologists treat ‘culture’ as a synonym for ‘tradition’, a term defined as objectively as any in the physical sciences. This is no more “emotional vocabulary”, to use Abler's description, than other everyday terms such as ‘intelligence’, ‘memory’ and ‘innovation’. These terms can also refer to distinctive phenomena in humans, but once objectively defined they are commonly and usefully applied in the science of animal behaviour.

Second, as I explained at greater length in my recent Progress article “The second inheritance system of chimpanzees and humans” (Nature 437, 52–55; 2005), some behavioural scientists do argue that the term and concept of ‘culture’ should be reserved for traditions that share certain sophisticated features with the human case, such as transmission by teaching.

Either perspective can be effectively employed in comparative and evolutionary analyses, but whichever approach is used, the needs of good science remain the same: when we use everyday words such as ‘culture’, they must be clearly defined.