Besides pleasure, arousal and ecstasy, sex has a deeper purpose. Animal species spread sexually not by chance. In sexual reproduction, the genomes of the two animals are mixed, forming a new genetic code in the new generation. The younger generation is much more resistant to various diseases and bacteria due to the newly built immunity. The crossing of two genes makes it possible to build a completely new genetic code, which is formed from the positive traits of the parent cells. This is a big plus when fighting various parasites and bacteria that evolve over time. Biologists describe the situation as “running with the Red Queen”, drawing an analogy with Lewis Carroll’s book “Alice in the Looking Glass”, which says: “You have to run as hard as you can to stay in the same place”. The genome stores all the hereditary information encoded in DNA. DNA permanently stores and transmits hereditary information through generations. Researchers’ analyzes support the theory of evolution. Although the theory is quite popular, until now there has been very little evidence to support it. To dispel any doubt, scientists at Indiana University created two types of worms using genetic engineering. One species reproduces sexually and the other by cloning. The researchers exposed the worms to a variety of viruses and bacteria and found that the ones that reproduced sexually were much more resistant to infection than the cloned ones.