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Are Humans the Only Species that Adopt?

We might not be so different after all. While humans commonly adopt babies, children, teens and even adults, our animal relatives sometimes do the same. And like humans, they don’t exclusively adopt babies that “look” like them.

Where and why does this happen?

Species Within the Animal Kingdom that Adopt

Animals that tend to have stronger social groups, including humans, seem to be more likely to “adopt” orphaned or rejected young. These can include troops of apes and primates, pods of dolphins or whales, elephant herds, wolf packs, bird nests and other tight-knit animal groups, as well as domesticated animals. It’s rarer for solitary-type animals to adopt. These would include wild cats, bears, rhinos, koalas, etc.

Animals most commonly adopt babies from within their own social group but will also adopt from within their own species or nearby groups and occasionally from similar species, like the rare case of capuchin monkeys adopting a marmoset. However, there have been even rarer instances of animals taking care of infants far outside of their own species.

Why Does This Happen?

Biologists don’t entirely know. The reason why it’s a source of scientific curiosity is because, in an eat-or-be-eaten world, adoption doesn’t really make a lot of sense. Here’s why:

  • Adopting young that isn’t biologically related to that animal means they’re not passing on their genes — a hard-wired drive for all animals to ensure survival of the species.
  • Adding a new mouth to feed takes precious resources, time and energy away from the others.
  • Caring for a baby into maturity may keep the adoptive mother from reproducing for a while longer.

It may seem cold, but these are important needs for all animals.

So, why would any animal adopt? The phenomenon has been studied and biologists have some theories:

Parental Instinct

The animals that have been most commonly seen adopting another animal’s babies are nursing mothers. Animals have those hormonal and emotional parental instincts that kick in, and a new mother may just be more receptive to welcoming more babies, like in the situation of the bottlenose dolphin that adopted an animal outside her species, a whale calf. There have also been cases of animals who were unable to have biological babies, or whose babies had died, who adopted.

The Relationship Has Potential to Be Mutually Beneficial

Sometimes, there’s safety in numbers. Adding a new member to the family may one day help provide protection or aid in securing food and resources. Groups of animals may be perfectly comfortable taking in babies that aren’t biologically their own because they instinctually understand the benefit of larger group numbers.

Like the birds that clean crocodiles and rhinos, there are plenty of inter-species partnerships that sound unusual, but work out for everyone involved.

Some Empathy May Be Involved

No, animals don’t think and feel quite like we do. And we can’t presume to know what’s going through their heads. But that doesn’t mean they don’t think and feel in their own way. Many animals grieve the loss of a child and seem to find peace in adopting a young animal that needs a mother.

Social companionship is important to lots of different animals, including humans. So it seems that, even if a young animal isn’t able to help pass on genes or contribute much to the group, their very presence may just be enjoyable to the group.

It’s Darn Cute

Whatever the reason and whatever the animal pairing, there’s something about seeing adoption outside of humans that’s especially cute! Maybe we like to see reflections of ourselves, or maybe we just like an “odd couple” story, but animal adoptions tug on the heartstrings.