Scientists have identified a gene that is partly responsible for the difference among people who remain oblivious to the odour of sweat and individuals who start wrinkling their noses at the slightest whiff of sweat.
Professor Doron Lancet, research student Idan Menashe, and their colleagues call the identified gene OR11H7P.
Writing about their findings in PLoS Biology, the researchers revealed that humans' could perceive up to 10,000 different odours, and that about 1,000 different genes for the smell detecting receptors in the olfactory "retinas" facilitated this function.
However, in humans, over half of these genes have become defunct in the last few million years. While some of the genes have "broken" in all people, others still function in some of the population.
The researchers made their experimental volunteers sniff varying concentrations of compounds that smelled like banana, eucalyptus, spearmint, or sweat. They compared the participants' ability to detect each odour with their patterns of receptor gene loss.
It was found that participants who had two genes with disrupting mutations were likely to be impervious to the offending odour, which individuals who were hypersensitive to the smell had at least one intact OR11H7P gene.
The researchers, however, admitted that not all variation was caused by genetic differences, and that environmental factors also appeared to play an important role.
They also observed that women were generally slightly more sensitive to many smells than men, and some individuals of both sexes were better or worse in across-the-board acuity to all odorants.