Males eager to be in the front line at the sexual race have chosen the worst strategy if they want their genes spread. A lot of insect species are "polyandrous" ("many males" in Old Greek). This means that a female will mate with more than one partner during the mating season.

But polyandry is found also amongst many mammals such as sousliks (ground squirrels) and evolved primates like chimpanzees. Many birds are polyandrous, like buttonquails, nandu ostrich and waders (shore birds); also a lot of snakes. Many studies have proved that the last male is most likely to be successful, but many of the explanations found were inconsistent.

Recently, Dr David Hodgson and Dr David Hosken from the University of Exeter's School of Biosciences, studying polyandrous females, especially in species who mate with more than one partner in rapid succession, discovered why the last male in line is most likely to impregnate the female.

It seems that last male's advantage is that - in fact - he uses his mate's previous partners' seminal fluid. The genital ducts of the female are a hostile environment for the sperm cells, mainly because of its acidity.

The previous sperms buffer this environment, so, in a "sperm friendly" ambient created by the first males, the last spermatozoons can outrun the first ones on their race to fertilize the egg. "The presence of seminal fluid makes the female body a more 'sperm-friendly' place", said Hodgson.

"When the first male mates with the female, his sperm are released into a fairly hostile environment. But, by the time the last male mates, the presence of extra seminal fluid can assist the journey of his sperm to the egg."

So, the last will be the first!