The peacock's tail and the nightingale's song both advertise their bearer's quality as a mate. Now we must usher a female trait into this gallery of marvels - the baboon's rear-end.
Leah Domb, of Harvard University, Massachusetts and Mark Pagel, of the University of Reading, England, have found that the degree to which a female baboon's sexual organs swell up when she is in oestrus are a good guide to her reproductive potential.
Females with larger swellings reach sexual maturity earlier, and are able to breed more frequently. They also have more offspring, more of which survive.
|Female baboons with larger rear-ends reach sexual maturity earlier.|
Males seem to read these signs - they fight more fiercely among one another for the chance to mate with big-bottomed females.