Which mammals have periods like humans?

The article discusses the menstrual cycles of different mammals, as explained by Dr. Chi Eziefula, a menstrual health expert. Humans, chimpanzees, bonobos, and some Old World monkeys are the only mammals known to menstruate regularly. These species shed the lining of their uterus, called the endometrium, during their monthly cycles. In contrast, most other mammals, such as dogs, cats, and rabbits, have estrous cycles, where the uterine lining is reabsorbed rather than shed. Some mammals, like elephants and whales, have menstrual-like cycles but do not bleed externally. The article notes that the reasons behind the evolution of menstruation in humans and other primates are not fully understood, but it may be related to factors such as the need for uterine preparation for implantation, differences in placental development, and the energy demands of pregnancy. The article provides a concise overview of the menstrual cycles in various mammalian species, highlighting the unique characteristics of human menstruation compared to other animals.