Compared to other mammals, reproduction i n women is characterized by low lifetime fertility, a slow pace of reproduction, and a large investment i n each offspring. The reproductive span begins relatively late i n life; births tend to be spaced at increasingly longer intervals unt i l they stop altogether. Many women then live wel l beyond ages at which reproduc­ tion is possible, something that is rarely seen i n other mammals. Making sense out of this pattern of reproduction has been a goal of anthropolo­ gists, demographers, physiologists, and evolutionary biologists.