By William Weir
on April 2, 2009 3:30 PM

The evolutionary purpose for those eyespots on butterfly wings have been the object of debate since Darwin's time. Darwin himself thought the ones on the upperside were to attract mates and the underside spots scared away predators.

A new study at Yale says he might have been right. Using evolutionary history models, Jeffrey Oliver of Yale's department of ecology and evolutionary biology and Yale biologists Antonia Monteiro and Kendra A. Robertson found that the upperside spots on bicyclus butterflies evolved more quickly than those on the underside. That's consistent with the theory that mate-attracting traits evolve faster than other traits.

As for where and how those eyespots evolved, Oliver will next use longer evolutionary models covering longer periods to for more details on their development.

Read the full study:
http://rspb.royalsocietypublishing.org/content/early/2009/03/26/rspb.2009.0182.abstract?sid=523f7648-a2d2-453e-8fb3-4576c8cf0041#aff-2