Behavioural ecology: Naked mole-rats on the move

In the 1970s, R.D. Alexander attempted to explain the apparent absence of eusociality in vertebrates by describing a mythical creature with all the traits needed for eusociality: probably a rodent, it would live a cooperative existence constructing an expandable nest in a safe subterranean environment, exploiting a large, almost risk-free food source [1]. Unknown to Alexander at the time, he had given an almost perfect description of the naked mole-rat (Heterocephalus glaber). These bizarre creatures, bathyergid rodents found in Africa, are in many ways more like social insects than like mammals. Virtually hairless and poikilothermic, naked mole-rats live in colonies of around 80 individuals which work cooperatively to excavate a massive network of burrows [2]. Like social insects, naked mole-rats exhibit the characteristics necessary for eusociality: reproductive division of labour, overlapping generations and cooperative care of young [3].