Parenthood: Mongooses Have A Learning Curve, Too
Banded mongooses that get stressed out while raising pups may invest less in their future pups, reports University of Exeter biologists in the journal Functional Ecology. It's a prime example of the "carry-over effect" -- the idea, essentially, that the physical results of a current action will affect the actions you perform in the future -- according to Jennifer Sanderson, a mongoose expert at the University of Exeter.
The carry-over effect means that an animal's decisions have repercussions down the line. The success of a migrating bird or mating mongoose will influence how the animal migrates or mates next season. "Everybody knows that your past can affect your future," Sanderson says, "and behavioral ecologists have recently been using this phenomenon to explain why animals vary so much in how much they invest in caring for offspring."
If a certain mongoose works hard to bring up pups in one season, her stress hormones will rise so much she won't want to expend as much energy caring for the next round of pups. (Though that might sound harsh to us, banded mongoose are cooperative breeders: moms, dads and relatives take turns raising these small carnivores together.) Each mongoose pup gets an adult escort -- not necessarily the mongoose who gave birth -- that grooms and protects the pup for about 10 weeks.
Though the carry-over effect isn't limited to mongooses (or humans), this is the first time that scientists have found a physiological source -- in this case, hormones. Michael Cant, a University of Exeter biologist, says he expected to find three things from the study: "firstly that individuals with high stress levels are less likely to care for the pups, secondly that caring for pups causes stress levels to rise, and thirdly that this increase in stress continues after they have stopped caring for pups."
Although there hasn't been a similar study of the carry-over effect of hormones in humans caring for kids, there is some indication that parents spend fewerresources on later-born children. On behalf of firstborn kids everywhere, sorry, little brothers and sisters.