I was amused by a story, on a site called EcoTravelLogue, that jumped to this conclusion: Because 67 percent of those who booked an "ethical holiday" were women, it "revealed" that women "care more about the environment and social impact of their holiday decisions than men."
The truth is closer to this: women book more of all sorts of trips than men. Both the saving-the-environment types of tours, as well as the selfishly biking every day for their own enjoyment types of vacations.
I don't really know what the men are doing while the women are out traveling the world with these groups. But I've noticed it during my travels too.
Unless trips were specifically "singles" trips, where the company tried to balance the number of men and women, most of my group vacations have been made up of couples and women. With a smattering of solo men.