Which are the best sperm for fertilising the egg ?

Just read this article below at Times online about the results of a recently published study into which sperm can swim the fastest.

Size does not matter when it comes to a sperm’s ability to reach and fertilise an egg, a study published today suggests.

Research in the London-based journal BMC Evolutionary Biology casts doubt on the common scientific belief that sperm with longer tails can swim faster. The speed at which a sperm swims is a key factor in its capability to fertilise an egg.

While a longer tail does mean more thrust, this can be cancelled out by the drag caused by a correspondingly larger head. The proportions of the sperm – and ratio of head size to tail length – is the key factor, the researchers found.

Stuart Humphries, from the University of Sheffield, who took part in the study with collaborators from the University of Western Australia, said: “It is commonly believed that selection for increased sperm performance will favour the evolution of longer sperm. In fact, the relative lengths of a sperm’s parts, rather than their absolute lengths, are likely to be the target of selection.” The authors added that looking at liquid dynamics could allow research to progress rapidly.

The artcile can be found here http://www.timesonline.co.uk/tol/news/uk/health/article5225778.ece