Mole-rats: kissing but not quite cousins. (Zoology).

Damaraland mole-rats live underground in rodent versions of bee hives, but their family ties aren't very beelike, according to a new analysis of their genetics.

Bees, ants, and some other truly social insects inherit genes in such a way that sisters tend to share exactly the same forms of an especially large proportion of their genes. Theorists have speculated that such extraclose kinship invited the evolution of the beehive social life.

Scientists have mused that inbreeding might also create an extraordinary degree of kinship among the two species of mole-rats that live in supersocial colonies.

However, one of them, the Damaraland mole-rat, doesn't seem particularly inbred at all, says Tamsin Burland of the University of London. In 15 wild colonies, most breeding pairs weren't close relatives. The members of a particular colony showed less than half the relatedness previously reported in naked mole-rats, the other social mole-rat species.

Finding rather loose family ties in the Damaraland colonies emphasizes the need to look beyond kinship when peering into the origins of social living, says Burland. Ecology may offer some explanations, since both mole-rat species live in unusually harsh environments where striking out alone can be fatal, Burland and her colleagues suggest in a May 22 Proceedings of the Royal Society of London B.--S.M.