It is almost infallible: if a baby cries inconsolably, having one of his parents pick him up instantly calms him down . A study published this week in the journal Current Biology shows that this is a response common to all mammals, from mice to humans. According to Kumi Kuroda, from the RIKEN Institute of Neurosciences in Saitama (Japan), "the mother's arms are the safest place for a baby to be." Moreover, evolutionarily we have learned to identify that when our mother carries us in the first months of life, our chances of survival increase .
Kuroda and her colleagues have shown that the moment a baby recognizes that they are in the arms of an adult, they stop fidgeting, their muscles relax, and their heartbeat slows rapidly . And using an electrocardiogram they have verified that in mouse pups the rate at which the heart beats also decreases when the mother gently grabs it from the back to move it from one side to the other, in addition to its crying (emitted in ultrasound) .
