According to researchers, the typical human hand is home to more than 150 species of bacteria, a far higher number than previously thought. The study identified 4,742 types of bacteria thriving(成長する、繁盛する)on 51 pairs of hands. Only 5 bacterial species were shared by all participants. On average, women carried 50% more species of bacteria on their hands than men, possibly due to the fact that men’s skin is generally more acidic(酸性の)and less welcoming to bacteria. Women’s use of moisturizers(保湿用クリーム)and cosmetics may also be a factor.