Question

What groups of animals exhibit the menstrual cycle?

Options

• All vertebrates including birds and reptiles

• Only human females

• Primates, including monkeys, apes, and human beings

• All mammals including dogs, cats, and cattle

Answer 1

The menstrual cycle occurs mainly in primates, which include monkeys, apes, and human beings. While other mammals have estrous cycles, the menstrual cycle is specifically characteristic of primates.