Even if you think all there is to know when it comes to the biology of beluga whales and narwhals, you probably don't know this: They go through menopause, just like women. According to a new study from the University of Exeter, both beluga whales and narwhals are now known to go through menopause.
After studying the remains of 16 different whale species, scientists found "dormant ovaries" in the older beluga and narwhal female whales.
The discovery is significant mostly because only three other species on Earth are known to go through the cycle and live for a significantly long time after: orcas, short-finned pilot whales and, of course, humans.
It's still unclear why exactly beluga and killer whales go through menopause (and therefore stop reproducing) later in life, but a good deal of research has been done when it comes to orcas and their reproductive cycles.
As Dr. Sam Ellis, one of the authors of the University of Exeter study explains in the research, "For menopause to make sense in evolutionary terms, a species needs both a reason to stop reproducing and a reason to live on afterward."
Dr. Ellis explains that orcas stop reproducing for a practical reason. Orca offspring stay with their mothers for life, meaning that as time goes on, her group is mostly made up of whales that are related to her.
"This increasing relatedness means that, if she keeps having young, they compete with her own direct descendants for resources such as food," Dr. Ellis explains. "The reason to continue living is that older females are of great benefit to their offspring and grand-offspring. For example, their knowledge of where to find food helps groups survive."
Basically: When female whales are older, their knowledge of, well, life is helpful to the rest of the group — so they keep on living.
Menopause is reflective of a much, much larger commonality between humans and some whale species, though.
Most notably, whales have extremely complex, social, and affectionate relationships with their close-knit groups that they travel and live with — a quality that one study out of the University of Manchester called "human-like."
Whales' tendency to support the overall well-being of the group is exactly why some species seem to live well beyond going through menopause — and evidence even more similarities may be discovered in years to come.