Pavitra Muralidhar, a Ph.D. student in the Department of Organismic and Evolutionary Biology at Harvard University, has developed a theory to explain why females of some species are more attracted to some males who have a lesser chance of survival. In her paper published in the journal Nature, she outlines her theory of selfish sex chromosomes and how it might work in nature. Mark Kirkpatrick, with the University of Texas has published a News and Views piece in the same journal issue, outlining the work done by Muralidhar.