So I read Think like a Freak, and then glimpsed through a well-intentioned collection of "Reading Comprehension Tests for Schoolchildren" (in Ukrainian), and I was appalled at how easily the latter book dismissed simple observation of natural experiments that it makes a token effort to describe in favour of drawing the moral.
There was the story of "the Mowgli Children", two girls who were kidnapped and raised by wildlife, then found by someone and taken back to live as humans. (So what if it is hardly true. When I Googled "feral children", other stories were too similar to this one in the ways that matter, including this one.) It says they never learned to talk, didn't live for long after capture (not longer than 12 years, if I recall right), never became truly a part of human society. The moral is that children need interaction with other people to develop normally, "and the tale of Mowgli is just that, a beautiful tale".
Well yes, it kind of seems just like a beautiful tale right from the point when the wolves start talking, I don't know what kind of a kid would miss that before the Reading Comprehension Test but stop believing it afterwards, but anyhow.
What did they die of?
Who answered them when they howled?
Were ever dogs afraid of them?
They did not master human language, but how did they communicate with people? They had to, somehow, or they would not live even that long.
And lastly: how do people weigh the sheer impossibility of two little kids ever surviving against the iron certainty that they would not be able to integrate back into human society - weigh it so lightly? If the reader is expected to take this on faith, how can one be anything but amazed that it is at all possible? When I read about other feral children, somehow being found and taken back never seems to mean good news for them, or for anybody else.
I haven't ever read or heard of "the Mowgli Children" in any other context. Only in this one, about three or four times, and yet it was always presented as an "anecdote of science", although everybody understands it leads nowhere (can't ever lead anywhere because ethics forbids recreating the experiment's conditions) and hardly signifies anything.
What other missed natural experiments do you know of?
If you just Google around there are a lot that hit the keyword that seem well attested.
Most of them are either cases of monstrous parental abuse (plus sometimes proximity to pets of the parent) or else the child was already at least a toddler (and often aged 3-7) when they went into the wild.
It is less surprising when you remember that in typical hunter gatherer societies the age at which children became roughly "calorie self sufficient" (not necessarily good nutrition, but able to gather enough not to starve) was around 4 or 5.
Parental neglect cases often have trouble walking, which is moderate evidence that "walking is cultural" in the sense that we might not have reliable instincts for learning to do it without having any positive examples and/or encouragement. Also these stories tend to support the idea of critical periods in language acquisition.
The ones that are usually hoaxes or gross exaggerations of real facts tend to be stories of very young children (like 0-18 month old babies) being literally raised by animals from scratch with no human input at all.
It is still too improbable. Any kid in the wild is a free gift to the predator. Not just a baby, or a toddler.
My friend who studies wolves is quite adamant that it is simply impossible, unless you count cases where a child spent a few days in their company, because wolves often leave their toys for later.