From "Bonding Matters - The Chemistry of Attachment" by Linda F. Palmer:
Human babies are born helpless, needing to be entirely cared for and protected. Luckily, they are [also] born with all the necessary tools and “instructions” to attain such care for themselves, and to become a loved and loving part of their family and society.
The ingrained neural and hormonal interactions provided for parent and child to assist them in this process are among the most powerful in nature... and our instincts can provide us with all the appropriate responses.
Without taking great efforts to avoid and ignore such urges, parents will naturally follow the advice of their neurons and hormones, nurturing their babies and maintaining physical closeness with them.
The Happy Hormone Hit Parade
Oxytocin - Bonding
... a chemical messenger released in the brain chiefly in response to social contact... especially with skin-to-skin contact. In addition to providing health benefits, [it] promotes bonding... and creates desire for further contact.
Vasopressin - Protection
Released in response to nearness and touch, vasopressin... helps the father bond to [his mate and to his baby]. Vasopressin reinforces [and tempers] the father’s testosterone-promoted protective inclination [providing] stability as well as vigilance.
Prolactin & Behavior
Prolactin is released in all healthy people during sleep, [and helps to maintain immune function]. In parents, it [promotes] devoted caretaking for the infant.
Opioids & Rewards
[These pleasure hormones] reduce pain awareness and create feelings of elation. Social contacts, particularly touch - especially between parent and child - induce opioid release, creating good feelings that will enhance bonding.
Norepinephrine & Learning
Norepinephrine helps organize the infant’s stress control system [and promotes learning].
Pheromones & Basic Instincts
Newborns are much more sensitive to pheromones than adults... Most likely the initial imprinting of baby to [parents' pheromones]... is a way nature controls brain organization and hormonal releases to best adapt baby to its environment. Of course, the other basic sensation an infant responds to well is touch, and coincidentally, ... pheromones can only be sensed when people are physically very near each other.
