This one dates back to the 13th century. Holy Roman Emperor Frederick II was a genuinely curious person. His mind got fixated on single question. What language will a baby speak if he is raised in complete silence.
Fascinated by the question, he allegedly decided to conduct an experiment. He took away infants from their mothers and gave strict orders to nurses to just take care for them, feed them, clean them but never to speak a single word, never to show any affection to them.
His guess was that the children would grow up speaking Hebrew. But the results were shocking, all the children soon died. They couldn't simply survive without love and affection.
The story of the whole experiment comes from a single 13th century account, written by a monk who didn't like the Emperor, so the full truth cannot be verified.
However, when orphans in Romanian orphanages in the 1980’s faced similar abandonment, the results largely matched what the monk had described centuries earlier. Many children had severe developmental abnormalities, low IQ's and a much higher death rate.
These experiments suggest that human beings have an innate need for love and affection during their developmental years and that deprivation of it can lead to lasting damage and even death.