What conclusion did Harry and Margaret Harlow reach in their research efforts with the monkeys?

Harry and Margaret Harlow concluded that attachment and social bonding are crucial for healthy psychological development in rhesus monkeys. Their experiments demonstrated that infant monkeys preferred to cling to a soft, comforting surrogate mother over a wire one that provided food, highlighting the importance of emotional comfort and maternal care over mere physical sustenance. This research emphasized the significance of love and affection in early development, influencing theories of attachment in both animals and humans.