Study

Brief communication: Swimming and diving behavior in apes (Pan troglodytes and Pongo pygmaeus): First documented report

Bender, Renato; Bender, Nicole

American Journal of Physical Anthropology, 2013

Peer-reviewedcase reportcaptive

What they did

Two captive apes that had been habituated to water from a young age were filmed swimming and diving voluntarily, and their stroke patterns described and compared with those of humans and of other primates.

Studied in: Pan troglodytes, Pongo pygmaeus
Sample size: 2 two individually habituated captive apes

What they found

Both animals swam and dived voluntarily and competently. Notably, both used a breaststroke-like leg movement rather than the alternating dog-paddle used by almost all other mammals, which the authors relate to ape adaptation for climbing rather than for quadrupedal ground movement.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

Apes can learn to swim, and the stroke they adopt differs from the mammalian default in a way traceable to arboreal ancestry.

How NatureHQ reads it

The relevant part for a gorilla page is the shape of the claim, not the species. "Gorillas cannot swim" is close to true as a description of what wild gorillas do — they avoid deep water, they have low body fat and dense build, and drownings have occurred in zoo moats, which is why those moats were replaced. It is false as a statement about physical impossibility: apes that grow up around water learn. The distinction between an animal that does not and an animal that cannot is the entire content of the question, and it is the kind of distinction popular framing habitually loses.

Limitations

Two individuals, both habituated to water from infancy — not typical apes.
Neither animal is a gorilla, so the extension is by argument rather than observation.
A case report, so nothing about frequency or general capability follows.