The fascinating reason newborn babies smell the way they do.

Ever sniffed a baby’s head? If your answer is ‘yes’ that question won’t seem even remotely strange. Because from their soft little scalps wafts one of the most delicious, delightful, intoxicating odours that will ever enter your nostrils.

It only lasts a few weeks, and science is still out on where it comes from (one popular theory holds that it’s the lingering scent of vernix caseosa – the white, cheesy, substance that covers babies when they emerge from the uterus).

But regardless, there’s a pretty good reason why it’s there.

Evolution. As anatomy professor Johannes Frasnelli explained New York Magazine, the newborn scent is believed to be part of what helps parents to, well, not abandon their child in those difficult first weeks.

“As anyone with a baby knows, newborns are not too much fun to be around. They sleep, eat, and make you change the diapers. Still, most if not all parents say that having a baby is one of the greatest experiences,” Frasnelli told the outlet.

“So, of course, there must be mechanisms which allow for a very strong bond between parents, especially mothers, and the baby. We think that the odour of babies is involved in one of these mechanisms.”

Year One talks taking your baby home from hospital for the first time. (Post continues below.)

Frasnelli in 2013 co-authored a study in Frontier Psychology that monitored the brain activity of 30 women — 15 who had recently given birth, and 15 who had never given birth — while they were exposed to a series of mystery odours.

When given the scent of two-day-old baby’s pyjamas, neural activity increased in the same reward-related areas of the brain that light up when enjoying food, or consuming cocaine. While it was stronger in the new mothers, the reaction was observed among all the women.

Whether men have a similar response is yet to be determined.

Of course, it's not only a baby's smell that compels us to care for them.

Researchers from Oxford University last year determined that, biologically speaking, babies rely on a combination of traits to elicit care-giving responses in adults.

Among this 'cuteness' arsenal is the composition of their face (especially those large eyes), their chubby cheeks, the cooing sounds they make and, yes, that newborn smell.

"Infants attract us through all our senses," said review co-author Morten Kringelbach, "which helps make cuteness one of the most basic and powerful forces shaping our behaviour."