They say it takes a village to raise a child, but in this case, it takes a pride. National Geographic explains that while researching lions in Zambia, biologist Thandiwe Mweetwa discovered that lionesses synchronize their reproductive cycles so they can raise their cubs alongside one another.
But for female lions, raising their cubs together isn't for social reasons; it's for the safety of their young. “Synchronized estrus is thought to increase reproductive success in the pride,” Mweetwa says. She goes on to explain that by getting pregnant and giving birth at or around the same time, the lionesses are with several other mothers to protect the cubs from rival male lions looking to kill them.
It's also a harsh reality that if a rival lion does kill some of the cubs, there are still others left to grow to be adults. National Geographic explains that if cubs were born at different times throughout the year, they could become a steady food source for predators and a year-round target for rival lions.
Another interesting part of Mweetwa's research points out that lionesses who lose their cubs at the same time will go back into estrus together. Having their babies at the same time also means that the lionesses can mate at once and cross-nest each other's cubs.
Synching of estrus in mammals isn't uncommon. National Geographic explains that many animals sync their cycles to the seasons, like deer, who mate in the fall and give birth in the warm spring and summer.
There's also a long-standing myth that women who live together sync their periods. National Geographic points out that research conducted by psychologist Martha McClintock in 1971 led to this common belief, but that many studies have since discredited it.
In fact, Jeffrey C. Schank, who did research on this subject with colleague Zhengwei Yang, says the matching of female menstrual cycles is just by chance. “It’s just a mathematical property of irregular rhythms, and rhythms of different lengths,” Schank told National Geographic. The University of California professor also notes that it's typical human nature to notice when things match, compared to when they don't.
Thanks to Mweetwa's research, we know that the synching of estrus in lionesses is very real. Check out the video below to hear what she has to say about her findings.