The purpose of life: why the textbook needs an update

New research from Australia and Finland could help explain one of nature's strangest quirks—why some animals forego mating to help other animals procreate. The study challenges decades-old ideas about evolution, and why animals behave as they do.

Credit: Steven & Courtney Johnson & Horwitz/Flickr

Co-author Professor Michael Jennions from The Australian National University (ANU) says it was traditionally thought that animals evolved to maximise their reproductive success—sometimes called 'Darwinian fitness'.

"It is logical. Any new traits which happen to result in more offspring will eventually spread throughout the population," Professor Jennions said. "It is why cheetahs run so fast and dolphins swim so well."

But why would some animals—like worker bees and meerkats—give up their own chances of reproducing to help others? British zoologist William Hamilton offered a solution back in 1964.

"Hamilton put forward the idea that animals can enhance the number of genes they pass on not only by producing offspring, but by helping relatives," Professor Jennions said.

"He suggested that animals should strive for high 'inclusive fitness' - which takes into account not only an individual's own offspring, but any impact on its relatives' reproduction."

However, a stumbling block in Hamilton's theory was its claim that an individual's inclusive fitness should exclude any offspring produced with help from others.