Yawning is a phylogenetically preserved and highly stereotyped behavior observed across vertebrates.1 In humans, it emerges early in development, as i…

Mothers can spread yawns to their yet-to-be-born offspring during pregnancy, researchers report May 5 in Current Biology  the first empirical evidence that behavioral contagion, long thought to be a social phenomenon of postnatal life, may have roots in the womb. Yawning is contagious among many social creatures, including humans, dogs, lions and parakeets. While the behavior is generally thought to boost blood flow to the brain for cooling and alertness — the so-called thermoregulatory hypothesis — yawning could also help synchronize group movements and serve as a primitive form of empathy.

Rather than catching a yawn on sight, muscles squeezing the uterus could be the trigger for a fetus to catch a yawn from its mother.