Within a few weeks, babies can recognize their caregiver, and prefer them to other people.

Within a month or so of being born, babies respond to the facial expressions.

• the smiles

• the meaningful looks

• the looking away and back again

• facial expressions are important in cementing a baby's attachment—just as much as your responses to their physical needs are.

Many babies adore being held from the start, but it takes about 6 months before they have the physical and cognitive abilities to ask for a pick-me-up.

Holding out their arms is a body-language expression of how much they've come to trust and love their parents. And it can be enough, especially on one of those endless days, to make your heart lurch too.