The Colombian-born evolutionary biologist Patty Brennan, assistant professor at Mount Holyoke College, studies something that reliably makes her the centre of any conversation: vertebrate genitalia. Far from turning squeamish or becoming bored by the details of her research, she finds most people are deeply fascinated by the often strange and surprising details of animal sex. And they’re right to be: as Brennan says, no other biological structures have co-evolved as closely as the vagina and the penis. Part of a Science series highlighting the work of extraordinary women in science, this short video explores Brennan’s efforts to learn more about the intricacies of animal copulation by dissecting, moulding and 3D-modelling animal genitalia. In particular, Brennan has found there’s still much to be learned about vaginas, which are underrepresented in scientific diagrams and research. This gap in knowledge is due not only to the challenges of studying something that’s inside the body, but likely also because the study of biology hasn’t escaped the phallocentricity of society.