January 2009 Archives
You may have seen or heard the recent headlines, along the lines of "Women's Hands 'Germier' than Men's." The report behind the rather misleading news flash is more interesting.
University of Colorado professor Noah Fierer studies the ecology of bacteria, fungi, and related microbes in natural systems such as soil, water, and the atmosphere. Turning his survey techniques to the human body, he looked at the diversity of bacteria on the hands of 51 students--all healthy except for the interesting twist that they'd all just finished their final exams. (Sweatier palms than usual, perhaps?)
Fierer and his colleagues used a gene-sequencing technique to count the number of different types of bacteria on each subject's hands. They tallied an impressive 4,742 types.
The quirky news headlines jumped out of the unexpected finding that the hands of female students harbored a greater diversity (but not necessarily more germs, per se) than did the guys'.
Just as interesting, perhaps, was the finding that while everyone seemed to share a core group of common skin bacteria, these common species made up just 13 percent of the total diversity. In fact, over 80 percent of the microbial species found on a person's left hand were different from those found on the right.
All this seems to suggest that most of the bacteria on our hands are fleeting transients. We pick them up as we touch objects, surfaces, and other body parts.
That said, the researchers found that hand washing--while a good idea when you're around others who might be ill--did little to change the diversity of the a palm's rainforest-rich ecosystem.