Cry Baby!

(1) The fact that crying is costly for young infants suggests that their behavior could provide honest signals of body condition, a useful thing for parents to know in order to adjust their care in favor of relatively strong babies likely to repay an additional investment of parental assistance.

(2, 3 and 4) Crying occurs most often at the time when growth rate and milk consumption are highest, in other words when the need for parental feedings is greatest.

(5) Babies that feed on demand cry less, which suggests again that crying is a signal of need, with babies whose needs have been met having nothing to gain from superfluous crying.

(6) The inability of unhealthy infants to produce costly signals of need and the tendency of their parents to invest less in these infants indicate that normal crying is an honest signal of need and that parents who attend to these signals are likely to be rewarded by having infants that survive the difficult early months of life.

Bio_man 8)