 A company anthropologist is dropped off alone on a remote planet where the settlers are being wiped out by a virus that targets the Y chromosome. All of the men and a lot of the women have been killed. She discovers that not only are the survivors surviving, but they are thriving and they are reproducing. How are they doing it? She suspects that the virus, in addition to killing half the population, is doing something else. In order to survive she has to go native and she gets caught up in a vicious inter-tribal war. Interesting book.