Why do some animals adopt other animals’ young?

Researchers in Iceland recently spotted an orca (Orcinus orca) with a whale calf. (Image credit: MarkMalleson via Getty Images)

Adoption is common among humans, who may decide to raise someone else’s child for a range of reasons, including fertility struggles or the wish to provide a home for youngsters in need.

But why do animals sometimes adopt the young of others? The act of caring for an unrelated, parentless infant probably emerged because it confers an evolutionary advantage on the foster parent, said Michael Weiss, a behavioral ecologist and research director at the Center for Whale Research in Washington state. For example, adoption may provide valuable caregiving experience for females that lack offspring and increase their future young’s survival chances, Weiss told Live Science.