How Do Animals Learn To Swim Naturally When Humans Don't?

To humans, swimming is a mechanically-complex exercise that requires lots of getting used to. For other mammals, however, swimming comes naturally, and they can stay afloat from the moment they're born. So how do some animals have this instinct while humans don't? Animals naturally learn to swim because they've evolved certain features in and around aquatic environments.

Body Features

Quadrupedal animals (animals who walk on four legs) enter the water in a position that allows them to swim more naturally. Humans and apes have an upright posture that makes the swimming motion much more awkward for their bodies to accommodate. A four-legged animal, on the other hand, is built to keep its mouth and nose above shallow water while swimming. Because most mammals walk on four legs, nearly all of them are able, in some capacity, to swim, though some are more used to water than others.

Take the doggy paddle, for instance. Though some dogs are better natural swimmers than others, a dog’s four legs are naturally level. When a dog swims, its limbs move similarly to how they do when walking, so the dog can adjust to the water more naturally than a human can.

Natural Selection

Over millions of years, animals that can swim have been naturally selected for survival in aquatic environments. Penguins, for example, have evolved into excellent swimmers in frigid waters to make up for their lack of flight. Different animals have evolved to swim for different reasons. While some mammals will motor into rivers to find plants to eat, others have developed the swimming instinct to escape predators that could otherwise outrun them. In fact, some mammals got so used to the water that they went from terrestrial to fully aquatic: fossils of prehistoric whales, for example, suggest they used to have four legs.

Unlike other mammals, humans never evolved swimming as a primary focus. Most primates evolved traits for a lifestyle high up in the trees, and have bodies more suited for climbing than swimming. On the topic of humans, in the span of millennia, they’ve actually “taught” some dogs how to swim better than others. Dogs initially bred for swimming, like retrievers and spaniels, are far more comfortable in the water today than small or stubby-limbed dogs who get overwhelmed by the water as soon as they’re dropped into it. Overall, while swimming comes naturally to animals today, it took millions of years of selective pressure for them to “learn” that swimming instinct, and sometimes humans taught it to them.

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