Six cases
“There is no sense of ‘I’ without its correlative sense of you, or he, or they.”
Charles Horton Cooley, Human Nature and the Social Order (1902). His looking-glass self and George Herbert Mead’s account of the self emerging through role-taking both require other people to already be there. Isolation is what it looks like when that requirement goes unmet.
Read these honestly. None of them are experiments on humans — they are crimes and disasters, described afterward. Every case is confounded: starvation, beating, and possible disability from birth are tangled together with the isolation itself, and no child can be re-run as a control. The bars above are a qualitative summary of what observers reported, not measured scores. The defensible conclusion is not “nurture wins” — it is that the capacities we call natural do not appear without other people, and that the same deprivation costs more the longer it runs.