For many organisms, it takes a village to raise the young – individuals other than the youngsters’ parents will provide care and help them to survive. In prairie voles, both adults and adolescents will care for babies, or pups, that are not their own. Recent work published by Caitlyn Finton and colleagues at Cornell University and Emory University, USA, suggests that adolescent prairie voles take care of pups to practice their parenting skills. But the hormones that drive adolescent caregiving behaviors are not the same as those that drive normal, adult parenting behaviors.
Finton and colleagues first tested why adolescent prairie voles would care for pups. The team thought that adolescents would either care for their siblings to pass on some of their related genes, or care for any pups that were around to learn how to become more competent parents in the future. The researchers raised families of prairie voles in the lab and chose adolescent males for their fostering experiments, as females tend to be more aggressive towards pups.
To test the adolescents’ caregiving motivations, the researchers put the prairie voles in cages with a sibling of the same age, a sibling pup or an unrelated pup. They then recorded how the animals behaved toward each other using a video camera and counted the amount of time that the adolescents spent grooming, sniffing or huddling near the other voles.
As expected, the adolescent prairie voles spent a lot of time around the younger voles. The adolescents also spent more time grooming and cuddling the pups than they spent caring for siblings of the same age, which aligns with the idea that prairie vole teens help care for young.
However, the team found no difference in the amount of time adolescents spent grooming, cuddling or smelling related and unrelated pups. This suggests that adolescent male prairie voles are practicing their parenting skills on unrelated pups rather than caring only for siblings to pass on some of their genes.
Next, Finton and colleagues tested whether the brain activity that drives teenage caregiving is similar to the activity that drives adult parenting. They looked at the expression of genes in brain cells of adolescents to understand how changes in brain activity relate to differences in behavior, predicting that cells that produce the parenting hormones oxytocin and vasopressin would change their activity after caring for pups, but not after interacting with siblings or an inanimate object.
Surprisingly, the researchers found that cells that produce oxytocin and vasopressin had the same activity regardless of whether the adolescents interacted with the pups or their same-age siblings. This might be because the area of the brain they looked at, the hypothalamus, is not involved in adolescent caregiving, or it could be that other hormones, such as estrogen, drive the adolescents’ behaviors towards pups.
Taken together, these results suggest that adolescent prairie voles raise pups to become better parents in the future, even if their teenage brains are not working like a parent’s brain.