Researchers have discovered that mice exhibit cooperative birth assistance, a behavior previously known only in humans and certain primates. This finding challenges assumptions about the limited nature of caregiving in the animal kingdom, suggesting that mutual aid during childbirth may be far more widespread than previously understood.
The Discovery and Experiment
The behavior was first observed during unrelated brain activity studies of mice in labor. Researchers at NYU Langone Health noticed that cage-mates actively intervened when a pregnant mouse struggled to deliver pups. To confirm this wasn’t accidental, they genetically engineered mice lacking oxytocin receptors — essential for uterine contractions — which often leads to fatal birthing complications.
The study divided pregnant mice into two groups: one paired with experienced mother mice, and the other housed alone. The results were stark. Nine out of ten mice assisted by experienced mothers survived labor, with 90% of their pups also surviving. In contrast, only one solitary mouse survived, and all her pups died. The “midwife” mice carefully extracted stuck pups, even breaking open amniotic sacs to allow newborns to breathe.
Why Experience Matters
Further experiments revealed that the helper’s maternal experience is critical. Mice paired with either males or females who had never given birth showed partial assistance — males used physical pressure to aid delivery, while non-mother females groomed and applied abdominal pressure — but failed to perform the crucial step of opening amniotic sacs. Only mice who had previously given birth acted as fully capable midwives, ensuring pup survival. This suggests that firsthand experience shapes the effectiveness of this caregiving behavior.
The Broader Implications
This study reinforces the idea that social cooperation, particularly during vulnerable periods like childbirth, is a fundamental aspect of mammalian behavior. “There are a lot of reasons mammals are social,” says study author Robert Froemke, “and a primary reason is to help each other out, especially in these really vulnerable periods.” The fact that mice struggle with childbirth and childcare, just like humans, underscores the evolutionary advantage of mutual support.
The study also highlights why this behavior may have gone unnoticed in the wild: animals seek seclusion during birth to avoid predators. The findings suggest that birth and rearing young may be central organizing forces in animal social networks, driving cooperation and survival.
The implications extend beyond mice. The researchers suspect similar behaviors occur in other rodents and mammals, suggesting that caregiving may be a more universal aspect of the animal kingdom than previously thought.
