Why can babies swim?

I’ve heard newborn human babies can swim. Can other newborn primates? Why would this be a useful instinct? (They can’t walk, and most babies are born on dry ground.)

I’m not basing this on any statics or anything, just lots of Reader’s Digest “Drama in Real Life” and a few too many episodes of Rescue 911, but it seems to me an awful lot of babies and toddlers that fall in swimming pools unattended drown. Maybe it’s because we don’t hear the stories of mothers getting off the telephone and going to look for baby only to find him swimming happily in the pool.

In addition, I’ve always been under the impression (mostly from reading Clan of the Cavebear) that other primates can’t swim, or at least not that well. I’ve seen the pictures of the monkeys covered in icicles sitting in the water, but it always looked to me like they were just sitting, not swimming or even treading water.

So here you go, all I know on the subject I’ve learned from Readers Digest, Jean M. Auel, and posters.

“I hope life isn’t a big joke, because I don’t get it,” Jack Handy

Babies under the age of 5 months naturally hold their breath and can swim. Mostly a hold over from the womb.

After the age of 5 months they need to be taught hold their breath again and how to swim.

To deal with men by force is as impractical as to deal with nature by persuasion.

Why would they hold their breath in the womb? They don’t have any breath in the womb! They get all their oxygen via the umbilical!

I suspect the OP may be confusing “swimming babies” with the practice of giving birth underwater. I have heard that some mothers choose to give birth while in a large tub. The baby then emerges into warm water rather than cold air, and is supposedly much less traumatized by the sudden change of being born. And they say the baby can remain underwater for as long as the umbilical cord is not cut, because that’s where he get’s his oxygen. Makes sense to me.

No, the swimming reflex in baby’s is quite well documented. The exact why of it is not known, but that babies hold their breath and make swimming motions when placed in water is fact.

>>while contemplating the navel of the universe, I wondered, is it an innie or outie?<<

—The dragon observes

Most likely the unattended babies were either over the age of a few months (The reflex fades after a few months, why again is not known. But is similar to the fact that a newborns grip is quite strong for a few months after birth, then fades.) or were unattended for too long, and the drowned after exhausting themselves. Not something one would care to do a study on, save of course via anecdotal evidence.

>>while contemplating the navel of the universe, I wondered, is it an innie or outie?<<

—The dragon observes

Babies in water is not a good idea… delivery-wise it is still a debate among doctors, but look at it logically, this swimming “reflex” some mention, that is exactly what it is. A reflex and nothing more. Babies do not know how to swim, they just sort of float naturally due to higher body fat percentage, the movement of arms and legs is strictly a reflex action carried over from fluid in the womb. If you plan on introducing your baby to the water you should wait until your baby has very good head control, usually at 5 months and up. I would not submerge a babys head because while they can hold their breath, they still swallow, and large quantities of water can lead to complications such as diluting of the blood, reducing sodium levels, and causing the brain to swell and then you get big problems, weakness, nausea, muscle twiching, stupor, convulsions, and even coma. Babies are much more susceptible to water intoxication than adults. Flotation devices can lend a false sense of security, there is no better safeguard than adult one-on-one supervision. It is also a good idea to know how to perform CPR on a baby if (pray it never happens) it is needed.

The babies’ instinctive swimming phenomenon has lead some to interpret that early man was mostly aquatic. No, not like fish, heads above water in lakes. This then ties into one of the explanations of why humans lost most of their body fur (compared to our anthropoid cousins), namely, hairless was more adapted to the water environment… except on top of heads, where it helped with temperature regulation.

CKDextHavn, interesting theory. Might that also explain why we have a webbing between our fingers that other primates don’t have?

So what’s this theory? Proto-humans lived in water for a while, long enough to cause some large evolutionary changes, and then became land animals again? Does any acheological evidence support this?


I find this hard to buy. I’ve watched films of newborns swimming, and I’ve watched ultrasounds and various films that include babies in the womb. I’ve never seen a baby “dog paddle” in the womb, nor does it seem that they would have any need to. What they do when they swim definitely resembles a dog paddle.

Many animals have inborn instincts to swim. Isn’t it natural to conclude that humans are born with this instict as well, but that our strong learning/reasoning nature quickly overwhelms it?

I want to know how this was documented. I can just see new mothers thumbing through the classifieds (“Wanted: babies less than 5 months old for sink or swim experiment”). I saw a documentary once showing that new born mammals all have the instinctive fear of heights. Baby humans, monkeys, kittens or puppies won’t crawl out onto the transparent portion of a plexiglass floor from the opaque portion, even with the mother on the opposite side encouraging the infant to come. I bet there was a large federal grant involved.

And if it’s something we all do instinctively, why do we need to be re-taught how to swim later in life?

This is not a “put your money where your mouth is” challenge, but I find this topic very interesting and would appreciate a cite or two from those of you who say that a swimming phenomenon in babies has been documented. Can anyone help me out?

I have no knowledge of this subject whatsoever, but I always thought that babies have a reflex to hold their breath if their faces are submerged in water, period. No “swimming,” just floating and limb-movement produced by the water. If you don’t take them out before they run out of breath, they would inhale water and drown. Correct or no?

The Johnson & Johnson Baby page says this:

Q. Can newborn babies swim when you first put them in water?
A: This myth is quite life threatening as very few infants do retain a psychological reflex known as the dive reflex, which enables them to hold their breath for a while, when they are under water. Most babies will not be able to swim or dive reflexively. They will on the other hand, gag and sink. So putting a baby in water to experiment and see whether the baby can swim can be quite a dangerous prospect.

But I have heard the “very young babies retain the ‘don’t inhale’ instinct” story too, but I think it was more like a few days when I heard it. So, there’s a half-assed citation.

They say I got the power, because I got the monkeys.
They are WRONG! I got the power because I am not afraid to let the monkeys loose.

I agree with Darkfox’s post.

For those that were wondering about my post I got the technical info from one of the two books no new parent should be without “What to expect the first year”

When I said that babies do not know how to swim, that part is my own thinking, there is no way they should know how to swim any more than they would be born knowing how to ride a bike, do math, or play the piano.

In the womb, babies “breathe” the amniotic fluid even though they don’t need it for the oxygen. (They also swallow and excrete it without drawing any nutrition from it.) I assume this is some sort of training for the lungs. It would certainly not cause a baby to hold his/her breath in water, so that reflex must be a different thing altogether.


I saw a documentary where some guy (vague enough?) was promoting his theory that humans were semi-aquatic in the distant past. According to him, our ancestors inhabited the shores of ancient lakes and this had a marked effect on our evolutionary course. Examples: our relative hairlessness and the streamlined orientation of the body hair we do have. If I remember correctly, he hypothesized that this lifestyle contributed to bipedalism, and when the lakes dried up we migrated.

I dunno; there didn’t seem to be much evidence, even in this documentary, to conclude that this is true. Besides, since when is hairlessness essential for swimming? Except for mammals that live entirely in the water (say, dolphins) having hair is not a big impediment. Labrador retrievers are pretty hairy and they swim just fine.

I think (personal opinion here) the baby dive reflex strongly resembles the startle reflex. Experiment: blow in a newborn baby’s face and see what happens.

As for other primates- I think it’s true (can’t pin down the sources at the moment, sorry) that chimps can’t swim because they have so little body fat that they sink like stones.

Hmm, Holly, I dunno about your swimming-chimp explanation. When I was in college, I had little enough body fat that I would sink in water; though I couldn’t float, I could swim just fine.

Please note that I am not encouraging the act of putting newborns in water, I was simply stateing that the swim reflex exists.

>>while contemplating the navel of the universe, I wondered, is it an innie or outie?<<

—The dragon observes

My newborn moves his arms and legs around in a rhythmic, circular pattern pretty much all the time, or at least when he’s upset. I suppose you could interpret it as a “swimming” instinct, but you could just as easily interpret it as a “dancing” instinct.

I’ve seen some of these “swimming baby” films. It looks to me like they’re not so much swimming as holding their breath (because they’re startled - someone always blows in their face before dunking them) and desperately flailing their limbs around, while completely submerged. I’ve never seen a newborn actually dogpaddle across the pool with his head above the water.

I think you may be misremembering the documentary. In the study I saw, young babies, who had recently learned to crawl, would go right off the “cliff”. It was only older babies, who had been mobile some time, who stopped at the edge; suggesting that fear of heights is learned, not instinctual.

“For what a man had rather were true, he more readily believes” - Francis Bacon

Gosh! I hope this works!


They say a picture is worth a thousand words, although I must say this fella looks more like he’s drowning than swimming!