A new study speculates on an interesting reason babies cry at night—it could be because they’re trying to prevent Mom from procreating and giving birth to a sibling. Sneaky!
The research, published in the journal Evolution, Medicine, and Public Health, hypothesizes that whether consciously or unconsciously, babies could be applying a “survival of the fittest” technique, preventing the birth of a new sibling that will compete for food and care from their mother.
“It’s clear that babies can get enough milk even if they sleep through the night,” evolutionary biologist David Haig told NPR. “The waking becomes a different issue. I’m just suggesting that offspring have evolved to use waking up mothers and suckling more intensely to delay the birth of another sibling.” Nursing a child, especially at night, can stop women from resuming ovulation soon after a pregnancy, explains NPR. By keeping Mom too tired to procreate, the baby guarantees that he or she won’t have to share her resources.
Not everyone agrees with Haig—it’s not just the baby who benefits from nighttime feeding, anthropologist Holly Dunsworth tells NPR. “There are so many good juices running through infant and mom,. It’s rewarding beyond the calories and hunger satiation for everyone involved. When you look at it from that perspective, waking up to feed looks more like cooperation than conflict.”
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