What a beautiful back!
Over the past 20 years, male swallows have developed longer and longer tails. To attract females and seduce them. A very rapid and obvious evolutionary change that has not been found in other species.

A matter of size. 'Girls, come and see what a long tail I have.'
A matter of size. "Girls, come and see what a long tail I have."

A beautiful back is an irresistible instrument of seduction. Not only in the world of men. Even the swallows (Hirundo rustica) rely on a beautiful back to make a massacre of hearts. But unlike humans, it is mainly the males that use a long, shiny tail to attract females. What surprises us even more, however, is the discovery of Anders Pape Moller, an evolutionary biologist at the Pierre and Marie Curie University in Paris, in over twenty years. Pape Moller observed an average elongation of 11.4 mm of male swallow tails, corresponding to a 10% increase. The genetic change occurred under the eyes of the researchers, and at a record speed, never recorded before in other populations of animals that live in the wild.
Rapid evolution. That evolution could act quickly, even a few decades, has already been established in other situations. In the Galapagos, for example, long periods of drought in the last 30 years have favored the development of larger and sturdier beaks in a species of sparrow that feeds on seeds, in turn increasingly harder and more resistant to break due to the climate warmer. But the changes shown by European swallows are happening even faster. According to Pape Moller, in this case too the cause would be climate warming, this time in the Sahara, where birds migrate in winter. The phenomenon would cause a reduction in available food and a severe natural selection among swallows, which would favor the survival of stronger males. And a long and beautiful tail is just synonymous with strength: keeping it in perfect condition requires great energy for males and perfect health. Females know it and then choose partners with longer and more tapered feathers. In the unconscious hope that children inherit their genes.

(News updated December 6, 2004)