Get a Big Head

[mensfe_admin]

Metro - November 25th.

Get a big head and you lose egg race.

Men always like to believe that size dos'nt matter. And, when it comes to sperm at least, that has proven to be the case.
Sperm length was thought all important as a long tail allowed an individual sterm to swim faster, beating stumpy rivals to fertilise an egg.
But, although increased tail length means more thrust, this can be cancelled out by the drag of a correspondingly larger head, scientists now say.
"It is commonly believed that selection for increased sperm performance will favour the evolution of longer and therefore faster swimming sperm", said Dr Stuart Humphries of Sheffield University.
"In fact the relative lengths of sperm's constituent part, rather than their absolute lengths are likely to be the target of selection" he told the journal BMC Evolutionary Biology.
A sperm cell consists of a head, a midpiece and a tail. The tail of flagellum, flicks back and forth to drive the cell forward.
New research suggests a combination of adaption could see a shorter sperm become the Michael Phelps of the fertilisation race. "It seems clear some assumptions regarding the physics of sperm locomotion have hampered our progress in understanding the processes mediating sperm competition," said Dr Humphries.
The next field to look at should be the area of liquid dynamics believe researchers.