More than a quarter of primate species form male-female pair bonds that scientists describe as “monogamous”. That’s much higher than the overall mammal average of 9 percent. But those statistics don’t mean that humans are somehow “meant” to be monogamous. In fact, scientists are still debating — and publishing conflicting theories — on why monogamy would have evolved at all. Carl Zimmer has an interesting column at The New York Times looking at two recent papers, and how they fit into an ongoing scientific fascination with our own sex lives.