If I were to find a baby fox or somesuch mammal, and run at it aggressively with a chainsaw, it would probably find a hole or a bush or something to hide in, where I would have a tough time finding it. Yet when a baby is playing hide and seek, it think it’s invisible if it puts its hands over its eyes. What gives? I thought we were the smart ones.
Being able to fend for oneself as an infant is valuable only if a) there is a critical need for it and b) a greater ability doesn’t contradict it.
We’re designed to be what we are, a slow-developing species that is helpless at birth and requires a long period of protection. This is the trade-off for the superior brainpower and abilities we get at the end of adolescence.
Obviously, therefore, humans did not have natural predators from which the young had to hide. The ability of adults to protect the young was sufficient. This is true for many mammals. It’s true for other animals as well, like birds.
Each species of animal has a unique selection of traits that are useful for its environment. Take an animal out of its environment and those traits are likely to be less useful or even hazardous. That’s how evolution works. Being able to fend as an infant was hazardous for humans in the environment the species found itself and the trait was bred out. (Oversimplified: more likely the trait had already been disappearing in our ancestor species, but the argument stays the same.)
Is this really true? I thought this sort of reasoning was limited to the Ravenous Bugblatter Beast of Traal… Not that babies are known for being especially intelligent or worldly.
If it is true, at what age do babies stop thinking this way?
We are. But we’re also born several years premature. If human babies waited to be born until they were at a stage of development comparable to newborn animals, their oversized heads (there’s that smarts thing) wouldn’t fit out the birth canal. Fortunately, those same oversized heads make the adults competent enough that they can care for the babies so well that they don’t need to hide.
Hide and Seek is a game. If babies feel actually threatened by something (a loud noise, say, or a large animal) then they take appropriate steps to deal with the threat, just like a fox cub would.
Of course, in the case of babies, “appropriate steps” doesn’t mean “run and hide” - they lack the physical skills for that. Usually it means “cry until your caregiver does something about it”. That’s a perfectly rational reaction when you’re as helpless as a baby
Toddlers who can run away are also totally crap at hiding, though.
Keep in mind there are lots of species that are even more helpless at birth than humans. Pandas, Kangaroos, many birds, and almost all fish.
When you consider the enormous difference in maturity rate between, say tigers, (Two year old tigers are entirely mature) and humans, (Twenty one year old tigers are mostly dead) the one month old baby should be compared with a three day old tiger.
Stuff that threatens human infants on a regular basis tends to become extinct, at least locally.
Tris
True. I’ve played hide-and-seek with many kids. Many of those age two to three (or thereabouts), think they’re incredibly well-hidden when they run away five feet and crawl under a table that’s three feet high and they’re still completely visible to anyone passing by (i.e. no floor-length tablecloth or anything).
Recently, I was able to “hide” from a two and a half year old by sitting in a corner beside a couch (I wasn’t hidden by anything in front of me). I was still in the same room as them. They were honestly confused and really couldn’t find me for about two minutes, until I “accidentally” sneezed and they found me.
I think many kids don’t pick up on being able to effectively hide (or have the ability to find others who are hidden) until they’re at least three or four years old.
Well, I wasn’t. It took my grandma 30 minutes to find me once in the 1 bedroom apartment, and she was a tough old bird. The oversized walk-in closet flilled with clothes and boxes was a natural hide-and-seek paradise though, to be fair.
I think for toddlers it depends on the person, although I’m not around toddlers much.
They’re also pretty crap at running away, in fact…
My nearly-five-year old can run like a cat with its tail on fire. Still crap at hiding, though 
It looks like some of my revision might be useful.
Children up to about the age or 4 or 5 have not developed a Theory of Mind. Generally they will fail the False Belief Task , importantly what this means is the kids will be rubbish at hiding because they belief “If I can’t see you, you can’t see me”. Chronos is right, if we were born later then the babies would be able to reason about the predators beliefs (I can’t see it, but it can see me crouching here with my hands over my eyes, damn it).
Don’t let her hear you calling her a toddler though! 
Seriously, cognitive development in small kids is a really fascinating subject. As well as “theory of mind” to which Chewie refers, there’s alsoObject Permanence which explains the way little babies play hide and seek/peekaboo … it’s not that they think you can’t see them when they’ve got their hands over their eyes - they think maybe you don’t exist at all!
Fortunately, small mammals don’t need Theory of Mind or knowledge of Object Permanence in order to teach them how to run and hide … just as well, since as far as I know only humans can have Theory of Mind (the jury may still be out on some of the more intelligent apes). They just go by pure instinct. It might look like they’re doing better than very young humans, but they’re not trying to do things as complex as small humans are
WAG - we are not really hardwired to ‘hide’ but to take up defensive positions when needed. As such we have to learn how to actually hide. Children who haven’t learned how to actually hide will default to defensive positions that would typically limit avenues of attack, or frustrate the attackers, like having a tree in between you and the attacker.
This whole thread has a slightly creepy John Wayne Gacy vibe to it. 
Sailboat
This article sheds some light on the subject.
I remember one of the women at work telling me about playing hide and seek with her nieces and nephews. She opened the door to a dusty old storeroom and decided she didn’t want to go looking through it and asked, “Are you hiding in here John?”
From deep in the shadows he replied, “No!”
My 2 year old was doing something odd yesterday, and I’m not sure if she was mimicking me or being serious.
Of course, she’s in that stage where she’ll “hide” somewhere totally obvious, like behind a half open door, and I say, “Where’s Cailaigh? Has anyone seen Caileigh?” in a silly singsong voice while she goes “giggle giggle giggle” (The silly voice is on the shaky theory that if she ever hides somewhere where I do need to find her before the tigers do, that she’ll understand this isn’t the Where’s Caileigh Game, but I digress.)
So yesterday, I had her on my lap and she pulled my hair in front of my face, Cousin It style, and said, " 'Ere Mama? Mama? Mama?" But she did it without any inflection - almost as if she was serious! And this is a kid who gets inflection better than diction - her consonants are almost absent, but I can decode her speech based on vowels and inflection alone. Did she really think I disappeared while she was on my lap and her hands were holding my hair over my eyes? Or was she playing? I don’t think I’ll ever know.
So, the court order is still in effect? JK.
I was a good hider (and still am). I hid under the cover of the hot tub once (went in fully clothed as to not leave a trail of stripped clothes, there is about 8 inches of air between the cover and the water) and it took the family about 30 minutes to find me.
I also hid on a shelf in my parents closet (when I was a kid) that was hidden by hanging shirts and I had to come out of hiding because I caused the baby-sitter to panic. She was about to call the police from what I could hear, she thought I left the house.
However, my children are crap at hiding. They hide in the same spots and they think they are cleverly hidden when you can clearly see limbs and hear giggles. I refuse to share my secrets.
I think she just didn’t recognize you with your hair in your face. Her mental image of you is without the hair, so she thought you were a different person.
A friend brought her two year old son into the office when I was sitting down and wearing sunglasses. He looked at me very very puzzled, then walked over to me and pulled the sunglasses down. I raised my eyebrows and smiled and he got that it was still me. He put the glasses back on my nose and started to walk away, then stopped, turned, came back to me and pulled the sunglasses down. I raised my eyebrows and smiled and he giggled. He then did the same thing six times. His mother was laughing so hard she had to sit down.