Why humans are the only primates that can swim

Primates & Swimming

Do Primates Other Than Humans Swim?

"Why we are the only primates that can swim?" is a good point to raise, but it leaves the impression of being a trick question because humans are not the only primates that can swim. Although there are conflicting reports on whether or not certain primates really can swim, reliable research shows that several other primates are quite good swimmers, and those species will be reviewed in this paper.

First, the human part of the story: humans can swim but must be taught to swim. According to Bob Hopkins, swimming instructor at the Sussex County YMCA in New Jersey, humans in the water "naturally go vertical" because "all of our body density is in our legs" and humans' buoyancy is in the chest -- our lungs. Therefore, humans swim in a "non-horizontal position" and that creates a lot of resistance to forward movement through the water, Hopkins writes.

Hopkins, who was trained at the U.S. Olympic Training Center in Colorado Springs and is certified by the American Swim Coaches Association and the National Interscholastic Swim Coaches Association, explains that swimming requires humans to "reprogram [our] neuro muscular memory" which, until humans hit the water, only knows dry land muscular activities.

Secondly, there are indeed primates that swim. The London Times reports that some naturalists are "shocked" when they see apes swim across a river in Borneo. In an April, 2008 piece, Lewis Smith writes that Orangutans had previously been thought of as non-swimmers, but on a research science trip to Borneo, scientists witnessed an Orangutan swimming across a wide river in order to get to "some of their favourite fruits at a conservation refuge on Kaja island" (Smith, 2008). Moreover, the Orangutan had not been identified previously as a swimmer, Smith adds, and the Orangutan that was being observed by the naturalists in Borneo (on Kaja Island) took a stick and stunned a fish before plucking it out of the water and eating it.

Unfortunately these apes are endangered, threatened with extinction, because of diminishing habitat.

Meantime author Loren Coleman, writing in the book Mysterious America: The Ultimate Guide to the Nation's Weirdest Wonders, Strangest Spots, and Creepiest Creatures (Coleman, 2007), insists that Orangutans do not swim. It is hard to know whether Coleman has even been to Borneo, or whether he's ever left the United States for that matter, but he insists (p. 211) in "pointing out that the orangutan of Borneo and Sumatra is constitutionally incapable of swimming the Mississippi or any other river, while our primate friends from the bottomlands seem to be able to do so without inordinate difficulty" (Coleman, p. 211).

Sounding self-assured, Coleman (p. 211) writes that "Most primates swim remarkably well, but authorities agree that anthropoid apes avoid water and cannot swim." Coleman doesn't mention what authorities he is alluding to, but he goes on to describe the fate of several chimpanzees who drown in various venues, including a chimp in the "moat of the new ape-house of the Antwerp Zoo" and a "gibbon in the London Zoo" that drowned "even in very shallow water at the bottom of its large cage" (Coleman, p. 210).

That having been said, Coleman (p. 212) references a book by British primatologist, Vernon Reynolds, The Apes, in which Reynolds is quoted: "A report from Spanish Guinea states that four chimpanzees were observed swimming across a 60 to 65-meter-wide Benito River. They made swimming motions like dogs…" (Coleman, p. 212).

Colin Groves writes in Nature Australia (Groves, 2004) that a researcher in Southeast Asia in the 1930s had a pet gibbon and tossed it over the side to see if it could swim. It could not, and nearly drown. However, Groves continues, there are species of primates that do swim. For one, the Long-tailed Macaque (Macaca fascicularis) "swims and dives for food"; another, according to Groves, is the Proboscis Monkey (Nasalis larvatus) of Borneo that "lives in big troops in mangrove regions and alongside rivers, sleeps in trees by rivers at night and regularly swims or wades" across rivers and creeks; and three, the Northern Talapoin (Miopithecus ogouensis) of West-central Africa (smallest of the "Old World monkeys") also sleeps on branches above water and when disturbed, "simply drops into the water and swims away" (Groves, 2008).

Phyllis Jay briefly touches on the subject of primates swimming in the book Behavior of Nonhuman Primates; in discussing the habitat of African monkeys, Jay writes (Jay, 1965, p. 535) that the "…distribution of arboreal monkeys is restricted by open, relatively treeless areas" and "rivers are barriers to arboreal monkeys but not to terrestrial forms, many of which swim" (Jay, p. 535).

"Long-tailed macaques are excellent swimmers, and this may be a predator avoidance technique," writes the University of Wisconsin's Kristina Cawthon Lang in Primate Factsheet. If the long-tailed macaque is threatened by a feral dog, raptor, python, monitor lizard or large cat, the macaque simply drops into the water and swims to safety (Lang, 2006).

In its "Science & Nature: Animals" section, the British Broadcasting Company (BBC) published a story on the Long-tailed Macaque: "Long-tailed macaques swim well and jump into the water from nearby trees" (BBC).

In his book, Primate Anatomy: An Introduction, Friderun Ankel-Simons explains that Macaques (not "Long-tailed macaques") live in many areas of the world, including Asia (India north to Afghanistan, Nepal, Burma, and Tibet, Thailand, Southern China, all the way east to Japan), the Philippines, Sri Lanka, Borneo, and sometimes the Macaques are established in artificial colonies.