It was reported in Nature that when a variety of coloured bands were placed on the legs of male zebra finches, the females vastly preferred males with symmetrically banded legs over those given bands of different colours on each leg (a silly appearance that could be likened, perhaps, to a male wearing mismatched socks). By an evolutionary hypothesis, a symmetrical body demonstrates that the individual's central operating systems are in peak form, and plays a role in desirability, particularly important in mate selection. This throws doubt on the claimed non-interference of other identifying marks (ear tags, paint and dye marks etc.) and monitoring apparatus that biologists place on animals in the wild.