Evolution

Why animals get bigger over time

Journal name:
Nature
Volume:
482,
Page:
8
Date published:
DOI:
doi:10.1038/482008d
Published online

In palaeontology, Cope's rule holds that species evolve larger body sizes over geological time. One possible explanation has been that competition favours bigger bodies. To test this, Pasquale Raia at the University of Naples Federico II in Italy and his colleagues compiled a species tree of 554 extinct mammals across the past 60 million years, and analysed size evolution within lineages.

They found that body size tends to increase as animals develop more specialized diets confined to particular habitats. Moreover, the origination of larger sizes coincided with periods of global cooling, and came at the cost of increased extinction risk.

Am. Nat. http://dx.doi.org/10.1086/664081 (2012)

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