Ashley Montagu is a 95 year old anthropologist. He arrived at this conclusion after a lifetime of studying mothers and their babies around the world.
It doesn't surprise me that someone who studies mothers and babies would reach this conclusion. It seems to me that loving is what every new baby does naturally. And a mother will instinctively love her baby if she is permitted to keep it with her from the moment it is born, and to nurse it.
A newborn is a wrinkled, wriggly, skinny little creature.
It loves to be held on its mother's bare skin.
Baby needs to be fed, kept warm, held close. It also needs to be clean and dry, to be burped. Baby needs sleep, and may need to be calmed so that it can rest.
Babies have few resources to meet their own needs. They can suckle, they can swallow, and they can cry. (Providing born at term.)
Most newborns sleep a lot during the first 2 weeks. This gives mother a chance to recover somewhat, before baby begins needing more attention.
The mother's attachment to her baby begins as soon as it is born. The first few hours after birth is a special "sensitive" time, during which mother's body is primed by hormones to cause her to bond with her baby. It is very important that she be able to hold and look at her baby during this special time. The wise obstetrician will place the baby on the mother's bare tummy before he even cuts the cord.
Having this wonderful time with her baby (I wanted it to last for a year.) prepares the mother to care for the baby's needs. It makes getting up at night to tend the baby so much easier, -- more of a pleasure than a duty.
Cite Klaus and Kennell
But more importantly, it is a fourth trimester of growth for the baby -- a transition from the womb to the world outside its mother's body. Some babies make this transition placidly. Others have a hard time with it.
Dr. Harvey Karp
Breast Feeding is Best Feeding
Smoking and Pregnancy
Answers to Questions about Children from the American Academy of Pediatrics