Gene sequencing of 102 hands by scientists from the University of Colorado at Boulder found that a typical hand harbours many more bacteria than previously thought. The study also concluded that the diversity of bacterial species was much greater on female hands.
332,000 genomes were sequenced which resulted in the identification of 4,700 bacterial species. An average hand is home to about 150 different species. Only 5 species were shared amongst the 51 participants to the study. On average the women in this study had about 50% more bacterial species on their hands than men.
The researchers gave several possible reasons for this, though these are just working hypotheses at the moment. It could be something to do with pH levels. Men's hands are more acidic than women's and this is generally not a pleasant environment for a bug. Or it could be something to do with hormones or differences in sweat and oil production.
Another interesting facet of this gene sequencing work was that the scientists found no difference in the diversity of bacteria after hand washing with an anti-bacterial soap. Some species were more abundant, others less so. However, researchers advocate people to continue using anti-bacterial gels, soaps and cleansers.
