Richard Collins: Long necks for sex... or snacks?

Researchers don’t rule out the necks-for-sex hypothesis, but they think that "the increased nutritional demands of females drove the evolution of giraffe long necks"

Douglas Cavener, of Pennsylvania State University, examined Masai giraffes in zoos and compared thousands of photos of them taken in Africa and in captivity worldwide. When born, males and females have similar proportions, but as they grow up, differences between the sexes appear. Picture: Larry Cummins

Kissing and cuddling is a rite-of-passage among teenagers. Condemned by Holy Mother Church, it was known as ‘necking’. The term isn’t used nowadays, but a modified version of it has surfaced in the most respectable of circles; zoologists are discussing ‘necks for sex’.

For Jean-Baptiste Lamarck, the giraffe’s neck was a favourite example of evolution in action. The necks of its ancestors had grown longer as the animals stretched upwards to reach leaves high in trees. As a result, he thought, the world’s tallest mammal gave birth to longer-necked offspring. But he has wrong; the muscles of blacksmiths' children are no bigger than office workers' children. ‘Acquired characteristics’ are not inherited.