Why are grown-ups and kids so different?
I’ve said it many times before: the questions children have are so fresh, so spontaneous and pure: they can be real mind-teasers. My six-year-old daughter asked me one day: “Why are kids so different from adults?” What exactly she meant, wasn’t clear to me, but the fact is of course that the young of most animals do, indeed, differ significantly from their adult relatives in many ways: size, looks, behaviour, attitude…..
Most humans would find a kitten or a puppy cuter than the adult cat or the grown-up dog; baby rabbits are adorable and little ducklings, I think, are some of the cutest creatures I can think of. And therein lies already one of the dissimilarities between “babies” and adults: young animals often possess rounder, cuddlier features and together with their clumsiness appeal to our parental instincts. The young of mammals and even birds exhibit what the 1973 Austrian Nobel laureate Konrad Lorenz used to refer to as the “Kindchenschema”, a distinct babyish look that reduces aggression and enhances attachment and feelings of care. Through their looks, the young, thus, derive not only protection from possible adult attacks, but they actually invite benevolence. The offspring of insects (think of a young bug, a baby louse or a maggot) and those of lower vertebrates like fish, however, do not touch our human sentiments in the same way.
Another aspect is diet – and that holds true even for insects and many other invertebrates. There are innumerous examples of animals in which the young and the adults consume totally different foodstuffs, take for instance leaf-munching caterpillars and nectar-drinking butterflies, Galactophagous mammalian infants and omnivorous adults. Quite frequently immature and mature individuals even live in separate environments: the largely herbivorous tadpole in the pond and the fly-catching adult or the plankton-filtering aquatic mosquito larvae and the adult bloodsuckers come to mind. Being so different has its advantages, for it leads to a better spread of resources, cf., food taboos in human societies. If offspring and adults all lived in the same area and all ate the same food, they would all be competitors – and most likely the smallest would be the losers. Not a very pleasant scenario for species in which the females lay hundreds of eggs. To occupy different niches and use different foodstuffs when you are young is, therefore, a very smart strategy.
But it necessitates differences in morphology and physiology, and as a consequence of that behaviour as well. That explains the familiar and sometimes grotesque unlikeness between larval and adult individuals. It seems as if Nature has tried to find ways to reduce conflicts between overlapping generations, but not necessarily within individuals of the same generation! The struggle to grow and survive is hard and immature individuals show little consideration for fellow individuals. It has even been suggested that human babies scream so much and are often so noisy at night (even if well fed and cared for) because it is in their interest to prevent their parents to find the time (or get in the mood) to produce another baby too quickly. That, in the eyes of the first baby, would only be an unwanted competition. Well, this bit of information, in reply to my daughter’s question, I withheld (she may find that out by herself one day).
© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2019.
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