Read More:
Babies cry at night in a bid to stop their mothers getting pregnant again and therefore ensuring their own survival
"It's the number one complaint of all new parents: a baby crying all night, but now it turns out infants may be programmed to monopolise mum's attention and stop her trying for another baby."

Babies cry at night to prevent siblings, scientist suggests
"When a baby cries at night, exhausted parents scramble to figure out why. He's hungry. Wet. Cold. Lonely. But now, a Harvard scientist offers more sinister explanation: The baby who demands to be breastfed in the middle of the night is preventing his mom from getting pregnant again."

Fear, anger or pain: Why do babies cry?
"Researchers have studied adults' accuracy in the recognition of the emotion causing babies to cry."

Crying in Infancy
"Crying in infancy is described as a loud, high-pitched sound made by infants in response to certain situations."

A Darwinian Look at a Wailing Baby
"Parents of wailing babies, take comfort: you are not alone."