Why do women have periods?
View full lesson: http://ed.ted.com/lessons/why-do-women-have-periods A handful of species on Earth share a seemingly mysterious trait: a menstrual cycle. We’re one of the select few mammals on Earth that menstruate, and we also do it more than any other animal, even though it’s a waste of nutrients, and can be a physical inconvenience. So where’s the sense in this uncommon biological process? TED-Ed describes the history and evolution of menstruation. Lesson by TED-Ed, animation by TED-Ed.
Why do women have periods?
Menstruation: A Biological Mystery
The transcript delves into the unique biological process of menstruation in humans and a few other species, exploring its evolutionary significance and the intricate dynamics between mother and fetus during pregnancy.
Menstruation as an Evolutionary Strategy
- Menstruation is a rare trait shared by only a handful of species on Earth, including monkeys, apes, bats, humans, and possibly elephant shrews.
- The menstrual cycle serves as a screening mechanism for embryos, ensuring that only healthy ones capable of successful implantation survive.
Evolutionary Conflict in Pregnancy
- Pregnancy creates an internal conflict between a mother and her fetus due to differing genetic interests.
- In humans and select species, the placenta penetrates the mother's circulatory system, allowing direct access to nutrient-rich blood from the mother.
Risks and Challenges of Pregnancy
- Pregnancy poses significant risks to maternal health due to the intense demands placed on the body by the developing fetus.