Why Animals Adopt

by Jessie Roberts


Humans aren’t the only animals who foster-parent. Jason G. Goldman highlights a study on the seals of Año Nuevo Island, off the coast of California:

[A]ll the foster parents were female. That’s perhaps unsurprising, since part of what drives orphans to seek out care is the need to nurse. Yet among females, the most common foster seal was a mother who had lost her own pup. Why might this be? One possible reason is that fostering helped these females reproduce later on. Regular nursing may induce ovulation, which in turn could make a female more likely to give birth to her own pup the following season. The evidence supporting this explanation is tenuous, but the hypothesis is at least reasonable.

Another possibility is that mothers are behaviourally and physiologically prepared to care for their pups immediately following birth. Given the absence of their own young, the motivation towards maternal care may be so great that they redirect their attention onto other, unrelated pups. Biologist George C Williams called this phenomenon “misplaced reproductive function”.

One other common form of adoption occurred when a female who had never given birth still cared for an unrelated infant. Riedman speculated that those females might gain valuable maternal experience, increasing their own parenting competence. So perhaps there is something in it for foster parents after all.

(Photo of elephant seal with pup at Piedras Blancas elephant seal beach by Anita Ritenour)