Although I would classify this as speculative, Noah Berlatsky writes that “Women Appreciate Good Booty-Shaking, Too” and that “Women can look at sexualized images of women all day every day.” Moreover, and perhaps more importantly, they do: look at the covers of magazines targeting women and you’ll mostly find… pictures of other women. Look at magazines devoted to men and you’ll also tend to find… women. Men like looking at women and apparently women like looking at other women.
This link may be NSFW, though it is primarily text, but the blog Pornhub Insights (which probably got started after the success of OkTrend’s data-driven blog about online dating) has a post called “What Women Want” that observes how “Pornhub’s Lesbian category is the leading favorite among the ladies, with Gay (male) following close at second place.” That’s a revealed preference not dissimilar to what magazines targeting women have also found.
A couple people have observed that my Flickr photos tend to feature more women than men, and likewise the photos on this blog. That may be true, but that may be because I’m giving audiences what they want.
I don’t have any good theories or research on the politics, cultural, or biology of why we might be seeing this phenomenon, but I do have a rationale for why I choose what I choose. Not every photographer will care about this, of course, but those who are contemplating what subjects people want to see should at least be cognizant of popularity.