A baby has around 30,000 taste buds, 3 times more than adults. They are not just on the tongue, but also on the sides, the back and the roof of the mouth, there are even some down their throats.

As we enter into puberty we lose many of these taste buds. Throughout our growth into adulthood we may lose as many as two thirds of them and be left with approx 10,000, most of which will be upon our tongue.

We have evolved to be repulsed by bitter foods whilst young…

As you can imagine, with 30,000 taste buds, this may explain the caricature-like expressions we have come to expect from our little ones when trying new foods; from tangy tangerines and sour cherries, to bitter olives and melt in the mouth savoury meats. Throughout the 5 taste senses: sweet, salty, sour, bitter and umami we can expect a wide and varied response, with all the degrees of exaggeration you’d expect with triple the amount of taste buds, compared those of a normal adult.

Sweet, high-fat foods are reminiscent of comforting breastmilk

There are reasons children dislike bitter foods and crave high-fat, sweet foods. Along with the increased taste buds, we have been evolutionarily pre-programmed to avoid some foods and crave others. Sweet, high-fat foods are reminiscent of comforting breastmilk and we need these types of food to flourish and thrive. Bitter foods, on the other hand, are harder to love and crave. We have evolved to be repulsed by bitter foods whilst young, to save inquiring little fingers and mouths from ingesting poisonous berries and leaves and only as adults do we learn to love them.

http://www.independent.co.uk/life-style/food-and-drink/features/the-day-i-ate-like-a-baby-the-secret-to-having-a-happy-eater-8298315.html