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| Lesser spot-nose guenon |
New research shows that old world monkeys avoid interbreeding by noting facial characteristics. Researchers from Exeter and New York Universites studied 1400 photographs of about two dozen species of guenons
(Cerocopithecidea), of which many different species live in close proximity to each other in sub-sahara Africa's forests. The study concludes that the striking appearance of these monkeys is due to sexual selection of visual signs that discourage hybridization. It is the strongest evidence to date that appearance in our own lineage makes a big difference to evolutionary processes. Oxford zoologist Jonathan Kingdon suggested the guenon's diversity of facial characteristics as an evolutionary adaptation to avoid inter-breeding in the 1980's. These latest results confirm his hypothesis. As one of the scientists involved put it, "You end up looking like those around you. With the primates we studied, this has a purpose: to strengthen reproductive isolation between populations".