The earthworms use touch to communicate and influence each other's behaviour, according to research published in the journal Ethology. By doing so the worms collectively decide to travel in the same direction as part of a single herd.
Worms forced to reproduce asexually succumbed to a nasty bacterial infection and died. The researchers say the results are the most convincing evidence to date for a key theory in evolutionary biology. The theory holds that sex evolved because it lets organisms reshuffle their genes into new combinations to stay a step ahead of parasites.