It's not like I look at the supposition and think 'well, no way this could work out well', esp. based on 1931 scientific thinking.

At least they used their own child as the subject as opposed to, say, a little Native American or Black baby as would've sadly been typical at the time.

Unfortunate that he committed suicide at 48. But then, so have lots of others, without having been raised 0-9 months with a chimp for a friend

than one psychologist, is more psychologists. I sure hope they couldn't do that to a child today.

Then I agree 100%. Because the experiment on the chimp was far more radical.

Human babies have grown up with primate friends like monkeys and lemurs (and other mammals like sheep and pig and cattle and cats and dogs) throughout all of history (especially in Asia and Africa). And Donald's own parents were clearly around for all of it, the chimp's parents were not.

These scientists did not have reason to believe it would harm their child or I'm sure they'd not have done so.

Guess the reason being that it was such a disastrous failure.

On June 26, 1931, comparative psychologist Winthrop Niles Kellogg and his wife welcomed a new arrival home: not a human infant, but a baby chimpanzee. The couple planned to raise the chimp, Gua, alongside their own baby boy, Donald. As later described in the Psychological Record, the idea was to see how environment influenced development. Could a chimp grow up to behave like a human? Or even think it was a human?

...

They raised the two babies in exactly the same way, in addition to conducting an exhaustive list of scientific experiments that included subjects such as "blood pressure, memory, body size, scribbling, reflexes, depth perception, vocalization, locomotion, reactions to tickling, strength, manual dexterity, problem solving, fears, equilibrium, play behavior, climbing, obedience, grasping, language comprehension, attention span and others," the Psychological Record authors note.

For a while, Gua actually excelled at these tests compared to Donald.

...
The experiment, however, ended rather abruptly and mysteriously. As the Psychological Record authors describe:

Our final concern is why the project ended when it did.

We are told only that the study was terminated on March 28, 1932, when Gua was returned to the Orange Park primate colony through a gradual rehabilitating process. But as for why, the Kelloggs, who are so specific on so many other points, leave the reader wondering.

It could be that the Kelloggs were simply exhausted from nine months of nonstop parenting and scientific work. Or perhaps it was the fact that Gua was becoming stronger and less manageable, and that the Kelloggs feared she might harm her human brother. Finally, one other possibility comes to mind, the authors point out: While Gua showed no signs of learning human languages, her brother Donald had begun imitating Gua's chimp noises. "In short, the language retardation in Donald may have brought an end to the study," the authors write.

They did damage to their own child and to the chimp social being.