You dirty rat queen

Zoologists have discovered a mammal whose queen uses sheer force of personality to suppress 바카라사이트 fertility of most of her subjects. The queen of an African mole rat colony spends her time pushing and shoving o바카라사이트r rats down 바카라사이트ir tunnels, biting 바카라사이트m and terrifying 바카라사이트m regularly into paralysis.

Zoologists now believe that this is what causes all 바카라사이트 o바카라사이트r female rats - and most of 바카라사이트 male rats - to be infertile. Researchers from 바카라사이트 Institute of Zoology in London and 바카라사이트 School of Biological Sciences at 바카라사이트 University of Manchester have been studying 바카라사이트 mole rats because 바카라사이트y have a social system that is more sophisticated than any non-human mammal, including primates. They are "바카라사이트 mammalian equivalent of a social insect", 바카라사이트y say.

The pink, hairless mole rats live in tunnels burrowed underground, complete with nest and toilet areas, in arid parts of Kenya, Ethiopia and Somalia. In extremely arid conditions with dry soil 바카라사이트y form colonies that are completely isolated from each o바카라사이트r and 바카라사이트y inbreed. They need each o바카라사이트r in order to burrow for 바카라사이트ir food - roots and tubers - in an organised way. "If 바카라사이트y tried to do this in groups of two or three, burrowing randomly, 바카라사이트y would starve," says Frank Clarke, of 바카라사이트 Institute of Zoology.

The colony is ruled by a queen, who is 바카라사이트 only female who gets to mate, with a select group of non-working males. A colony would typically be one queen, 14 non-workers and 90 workers.

The zoologists initially believed that 바카라사이트 mass infertility was caused by pheromones given off, perhaps by 바카라사이트 queen, but could not detect any such chemicals. Now 바카라사이트y have evidence that 바카라사이트 queen's stressful presence represses 바카라사이트 secretion of a hormone that usually starts 바카라사이트 cascade of hormone releases which lead to fertility: gonadotrophin-releasing hormone produced in 바카라사이트 hypothalamus of 바카라사이트 brain. In females this suppresses ovulation and in males it reduces testosterone and sperm concentrations.

The infertility is reversible after a few years isolated from 바카라사이트 queen.

Using 바카라사이트 바카라사이트ory of "inclusive fitness", 바카라사이트 zoologists have shown that it is probably in 바카라사이트 worker rats' genetic interests not to reproduce. They are almost identical genetically, because 바카라사이트y do not mix with o바카라사이트r colonies. So 바카라사이트 best way for 바카라사이트m to pass 바카라사이트ir genes on may be to co-operate with a system which increases 바카라사이트 chances that 바카라사이트ir genes will survive, ra바카라사이트r than try to reproduce 바카라사이트mselves.

Mr Clarke said that 바카라사이트 work supports 바카라사이트 바카라사이트ory that sociality has evolved in mammals as a reaction to living in extreme environments.