Why Are There So Few Smart Mammals (but So Many Smart Birds)?

Main Category: Biology / Biochemistry
Also Included In: Veterinary
Article Date: 08 Oct 2008 - 3:00 PDT

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We show that larger-brained birds and mammals have a lower lifetime reproductive capacity. This finding has two major consequences.

First, larger-brained species should be more extinction-prone. Thus, brain size, not body size, is responsible for the rule that larger animals are more extinction prone.

Second, each lineage has a maximum viable brain size ("grey ceiling"), which can only be surmounted if mothers receive energetic inputs. Indeed, in cooperatively breeding mammals and most altricial birds, we find no evidence for a trade-off between reproductive capacity and brain size.

Because helping is common in birds, the number of large-brained lineages is higher in birds than in mammals.

Royal Society journal Biology Letters

Biology Letters publishes short, innovative and cutting-edge research articles and opinion pieces accessible to scientists from across the biological sciences. The journal is characterised by stringent peer-review, rapid publication and broad dissemination of succinct high-quality research communications.

Biology Letters