Drop a dog, cat, horse, or even a mouse into water, and they'll instinctively paddle to safety using their natural walking motion. But throw a human—or any great ape—into a pool, and disaster strikes immediately.
Humans share a bizarre aquatic disability with our closest relatives: chimpanzees, gorillas, bonobos, and orangutans are all naturally terrible swimmers. We're among the only mammals on Earth that must be taught this crucial survival skill—and without training, we'll drown.
Most mammals can swim from birth because their four-legged walking motion translates perfectly to a doggy-paddle in water. But humans and great apes evolved to walk upright on two legs, losing the natural swimming advantage that quadrupeds possess. Our bipedal anatomy means we can't simply transfer our walking motion to water.
Zookeepers have exploited this weakness for decades, using water-filled moats to keep captive apes from escaping their enclosures. Tragically, some apes have accidentally fallen into these moats and drowned because they lack even basic swimming instincts to save themselves.
The Congo River's depths have even shaped primate evolution in dramatic ways. Scientists believe bonobos and chimpanzees developed into two completely different species because their common ancestors couldn't cross the waterway when it flooded between one and two million years ago.
On the north side of the Congo, ancestral chimpanzees faced competition with gorillas and developed aggressive, war-prone personalities. But the primates trapped on the south side faced little competition and evolved into the friendly, cooperative bonobos we know today—all because a river created an impassable barrier for non-swimmers.
In the wild, reports of great apes swimming are virtually nonexistent. The fear of water runs so deep that even shallow streams can prevent apes from accessing food or territory.
Human babies do display some water reflexes that might look like swimming. Until about 6 months old, infants have a "dive reflex" that makes them hold their breath when submerged, and a "swimming reflex" that causes them to move their limbs. But these aren't true swimming abilities—they're automatic responses that disappear quickly.
These reflexes have tragically given some parents false confidence that babies can swim, leading to drowning incidents. Pediatric experts warn that these reflexes don't protect infants from drowning—they're simply evolutionary holdovers that aren't sufficient for survival.
But here's the fascinating twist: once humans learn proper technique, we dramatically outperform every other terrestrial mammal in the water. Unlike other mammals stuck with the doggy-paddle, humans have developed sophisticated swimming strokes—freestyle, breaststroke, butterfly, backstroke—that make us aquatic champions.
A handful of captive apes have even been taught to swim with extensive training, proving that this disability can be overcome. But humans remain the only great apes that routinely master swimming—and when we do, we become better at it than any naturally-swimming land mammal on Earth.