Scientists discover the point of sex

Now researchers have discovered that animals reproduce together, rather than simply cloning themselves, because it helps them to ward off parasites.

The findings support the evolutionary theory that blending of two animals' genomes creates an offspring with a new genetic code which may make it more resistant to attack, experts said.

Cross-fertilisation helps creatures stay a step ahead in the continuous "arms race" with parasites, which are forever evolving to try and infect them.

Biologists have described the situation as "Running with the Red Queen" in reference to the character in Lewis Carroll's Through the Looking-Glass, who tells Alice: "It takes all the running you can do, to keep in the same place."

Despite the popularity of the theory, there has until now been little solid evidence to support it.

But experts at the University of Indiana may have provided the best evidence yet after engineering two types of worms, some which could only reproduce by mating with each other and some could only clone themselves.

After exposing them to a harmful bacteria, worms that reproduced through sex survived fairly well while those that were asexual died rapidly.

Co-author Curtis Lively said: "The Red Queen Hypothesis predicts that sex should allow hosts to evade infection from their parasites, whereas self-fertilisation may increase the risk of infection.

Read more at The Telegraph