Human infants are born at a much earlier stage of brain development than their primate cousins, and physically they are pretty helpless.
Indeed, it takes around nine months for a human baby to catch up with the skills of a chimpanzee newborn. That means they've had to develop oh-so-cute looks to make adult protectors putty in their hands, and desperate to feed and protect them.
Scientists have even worked out the facial formula they use to do it - known as the baby schema, or the cute code.
Evolutionary psychologist Michael Price, of Brunel University, explains: 'The baby's eyes are relatively large compared with the rest of its head.
'Their eyes are also lower down on the face than an adult's; they have bigger, more protruding foreheads.'
The reason we love a baby's face so much is that over millions of years we have developed an in-built, subconscious template of what we think is un-threatening.
Although not completely understood, one theory is that the proportions of babies' faces, with their soft curved cheeks and large, round eyes, are the opposite of how an aggressive enemy looks on the attack.
Indeed, studies have shown that when adults are shown pictures of babies which closely match this ideal, it triggers the reward centres in their brains.
It's a template which also seems to exist in the animal kingdom because kittens and puppies have similar proportions.
Even those bonny, baby cheeks are there for a reason, adds Michael. 'Healthy babies appear chubby, so chubbiness makes parents think the baby is going to survive, and motivates them to invest time and resources to look after it.'
A baby's eyes are especially designed to lock their parents' eyes in a loving gaze. As well as the fact they look large - by nine months old, they are already at their full adult width - babies have pupils which dilate more, making them look more appealing.
It may be the reason that most Caucasian babies are born with blue irises: a paler background contrasts much more starkly with the black pupils, making their 'come hither' signal all the more difficult to resist.
THEY HAVE SUPERHERO SENSES
Are you pulling your hair out because your nine-month-old is so fussy about eating solid foods?
The reason they do this is that babies have about 10,000 taste buds, around twice the number of an average adult, spread out over a much wider surface of the tongue.
It helps to explain why they are so fussy and spit out so much pureed food once we start weaning them. These taste buds die off over time and are not regenerated.
Again, this makes good survival sense, say scientists. A baby who can identify and prefer the taste of its mother's milk above everything else is much more likely to thrive and survive.
They are also seeing things much more clearly at this age. Sight is the one sense that improves with age. Newborns can only see about seven to 12 inches in front of them in order to allow them to concentrate on getting to know the faces of their parents. By around nine months, babies are ready to explore the world and can see almost as well as adults.
THEY GROW INCREDIBLY FAST
As every parent knows, one of the most astonishing things about babies is how fast they grow.
Although not unusual by the standards of other baby animals, which have to learn to survive on their own much sooner, infants increase in size in their first years much faster than at any other stage of human life.
On average, newborns double their birth weight by four months, and have almost tripled it by the age of nine months.
If they kept growing at the same rate, they would reach the average size of an adult by the age of three.
A human infant's brain also grows at a phenomenal speed, compared with other mammal babies.
At birth, it accounts for about ten per cent of a baby's total weight, which is also why their skulls are so large. A baby's head takes up a quarter of their full height.
By the time a baby hits nine months, its brain has almost doubled in weight and is around 50 per cent of its full adult size.
THEY ARE GIFTED MIMICS
To the adult ear, a baby's cry at the age of nine months may sound like any other call for attention.
But what you may not realise is that they've already picked up your accent - and have been learning to copy you since before they were born.
Several studies have found that as soon as they come into the world, babies are tuned into the language and regional accents they've been listening to through their mother's belly since their hearing started developing as six-month-old foetuses.
Researchers at the Centre for Pre-speech Development and Developmental Disorders at Germany's Würzburg University studied the cry 'melodies' of 60 healthy newborns, of which 30 were French and 30 German.
They chose these nationalities because French speakers typically raise their pitch at the ends of words and phrases, while German speakers end on a down-note.
When the infants' cries were studied, it was found infants were no different: French babies' cries tended to end on a rising note, while the inflexions of the German babies went down.
At the age of nine months, it means that even if your baby has not said its first words and is only babbling, it will already be making sounds with inflections which are peculiar to your mother tongue.
THEY HAVE WINNING SMILES
We all love a smiley baby - and by the age of nine months, it's the easiest way for babies to communicate to you that they are happy, but it's also essential to survival.
Unlike their ape cousins, human babies don't have their mother's fur to cling on to in order to keep them close. And the monkey-strength grip with which they are born - known as the palmar grasp - disappears after a few weeks. Like all professional survivors, they've managed to turn this evolutionary disadvantage to their favour: a hair-free face makes a winning smile much easier to see, all the better to lure, seduce and keep their care-givers close-by - just as effectively as clinging to their fur.
Studies show they don't learn this - it's an inbuilt ability. Blind babies also start to smile around the same age of six to eight weeks, despite never having seen one themselves.
Anthropologist Desmond Morris, author of Babywatching, says: 'The reason we have smiles and apes and monkeys do not is quite simply because they have fur and we do not. A human baby can't cling on strongly enough to make sure that the parent stays close to it.
'It needs something extra - something that will be so appealing to the parents that they will not be able to drag themselves away. And that something is the smiling face.'
THEY HAVE AMAZING MEMORIES FOR FACES
Do you have trouble picking people you know out from a crowd? Nine-month-old babies don't.
Tests which track an infant's eye movements have found that it can recognise its mother's features from the age of about two or three weeks. By four months, scans of babies' brains show that when they see a new person, they use as much of their brain power to analyse, process and remember it as an adult when they are introduced to a stranger.
In fact, their recognition skills may be even sharper. While monkeys in a zoo all look the same to adults, young babies appear to be able to tell them apart.
THEY'RE BUDDING PHYSICISTS
You might think that it would take a while for a baby, who is brand new to the world, to understand the basic laws of the universe. But even before their first birthday, human infants have been found to already understand the rudiments of physics - liquids pour, solids can be lifted and thrown and objects will fall if you drop them - according to the study in the journal Cognitive Science.
Again, this skill is hard-wired into their brains for survival. After all, understanding how liquids move and behave is crucial when you have to consume them every day as your main source of nourishment.
THEY KNOW RIGHT FROM WRONG
Parents assume they will have to drum the difference between good and bad behaviour into their baby as they grow older.
In fact, little ones already seem to have a pretty good idea from the start. In one experiment, babies aged between three and 19 months were shown a puppet show, featuring a rabbit that behaved well and one that was naughty.
In the first act, a cat character is seen opening a big plastic box. When he can't open the lid by himself, the friendly rabbit comes to his aid.
In act two, the scene is repeated. But this time a 'bad' bunny comes along and instead of helping the cat, slams the box shut before running away.
Afterwards the babies were presented with the puppets - and 80 per cent made a grab for the 'good' bunny, showing they preferred it.
Scientists at Yale University's Infant Cognition Center believe telling nice from nasty people is a skill that's hardwired because babies need to know from the start who is friend and who is a foe.
At the age of nine months, the skill is honed to distinguish between people they know and trust - and potentially dangerous strangers.
THEY'VE MORE BONES - BUT NO KNEE CAPS
They may look like they need them to do all that crawling, but at nine months old, babies don't even have knee caps - only soft bits of cartilage. These don't harden into bones until they are about three years old.
Their skull is also a patchwork of different bone plates, rather than one continuous surface.
In between are gaps - or soft spots - which allowed the skull to compress slightly during birth and also allows for the brain and skull's phenomenal growth during the first year.
In fact, a baby has more than 100 more bones than a grown-up because it can take until they reach adulthood for all the joins to be complete, in places like their pelvis, vertebral column, feet and hands.
THEY SWIM LIKE FISHES
After spending so many months floating around in fluid in the womb, no wonder babies feel at home in water.
That's why human babies have the knack for swimming as soon as they are born.
Studies of babies gently placed face down in warm, chemical-free water have found that until the age of about three months, they already have a talent for it. They kick their legs and push themselves forward in a swimming motion.
Scientists believe this early instinct is a throwback to our aquatic ancestors because other baby mammals do the same.
Although this is lost by the time they are nine months old, babies of this age have another advantage.
When they feel cold water on their faces, it triggers a second reflex - which lasts only for a few more months - which makes them automatically hold their breath and open their eyes underwater.
Tanith Carey is author of Taming The Tiger Parent, published by Robinson.
- Daily Mail
