"In research published online April 28 in Nature Methods, the scientists report that the presence of male experimenters produced a stress response in mice and rats equivalent to that caused by restraining the rodents for 15 minutes in a tube or forcing them to swim for three minutes. This stress-induced reaction made mice and rats of both sexes less sensitive to pain. Female experimenters produced no such effects." The senior author of the paper, Jeffrey Mogil, suggests that the "problem is easily solved" but curiously, he doesn't suggest the easiest solution of all, which is to simply ban men.
not all men