Menopause is the time of life when menstrual periods come to a halt, and a woman is no longer able to bear children. The most obvious cause of menopause is when the ovaries run out of eggs, though it can also be caused by a variety of other medical processes. While menopause is in many ways well-understood, the biological reason for menopause, or the way in which it evolved in humanity remains a mystery. The process was once thought to be virtually non-existent in the animal kingdom, raising further questions.
Surprisingly recently, however, scientists began to learn that humans are not alone in this trait. Indeed, a small handful of sea-going mammals also go through this unique and puzzling process.
Life Beyond Reproduction
The vast majority of species in the animal kingdom do not typically experience menopause. These creatures typically die while still capable of reproducing with a mate. Homo sapiens, then, are the outlier; typical human ovaries run out of eggs somewhere between the ages of 48 and 52, in sharp contrast to the worldwide human life expectancy of over 70 years. Indeed, it’s not uncommon for humans to live decades beyond the end of menses.
It was only in the early 1980s that scientists began to learn that humans weren’t completely alone in experiencing menopause. Scientists Helene Marsh and Toshio Kasuya had been working together on studying the reproductive systems of short-finned pilot whales. Having collected samples from 300 animals, Kasuya determined their age from counting growth rings in teeth, much the same way as with trees. Meanwhile, Marsh examined the ovaries. The data showed that most of the whales stopped having children around 36 years old, but that they ..
Support the originator by clicking the read the rest link below.
