The results, published in the journal Biology Letters, are from a study jointly carried out by Professor Robin Dunbar's lab at Oxford University and Professor John Manning at Northumbria University.
Previous physical comparisons between humans and other mammals suggest that humans are mid-way between being a faithful species and a promiscuous species. Research by Dr Rafael Wlodarski and Professor Dunbar in Oxford University's Department of Experimental Psychology suggests that this may actually be because humans consist of two separate sub-populations of people: one group is more interested in short-term flings, while another would like to form long-term commitments.