happens?”
“Yes, but it’s not only a question of food. It can be just as vital to avoid
being eaten by other animals. For example, it can be a matter of survival to
have a protective camouflage, the ability to run swiftly, to recognize hostile
animals, or, if the worst comes to the worst, to have a repellent taste. A
poison that can kill predators is quite useful too. That’s why so many cacti are
poisonous, Sophie. Practically nothing else can grow in the desert, so this
plant is especially vulnerable to plant-eating animals.”
“Most cacti are prickly as well.”
“The ability to reproduce is also of fundamental importance, obviously.
Darwin studied the ingenuity of plant pollination in great detail. Flowers glow
in glorious hues and exude delirious scents to attract the insects which are
instrumental in pollination. To perpetuate their kind, birds trill their melodious
tones. A placid or melancholy bull with no interest in cows will have no interest
for genealogy either, since with characteristics like these, its line will die out at
once. The bull’s sole purpose in life is to grow to sexual maturity and
reproduce in order to propagate the race. It is rather like a relay race. Those
that for one reason or another are unable to pass on their genes are con-
tinually discarded, and in that way the race is continually refined. Resistance
to disease is one of the most important characteristics progressively
accumulated and preserved in the variants that survive.”
“So everything gets better and better?”
“The result of this continual selection is that the ones best adapted to a
particular environment—or a particular ecological niche—will in the long term
perpetuate the race in that environment. But what is an advantage in one
environment is not necessarily an advantage in another. For some of the
Galapagos finches, the ability to fly was vital. But being good at flying is not so
necessary if food is dug from the ground and there are no predators. The
reason why so many different animal species have arisen over the ages is
precisely because of these many niches in the natural environment.”
“But even so, there is only one human race.”
“That’s because man has a unique ability to adapt to different conditions
of life. One of the things that amazed Darwin most was the way the Indians in
Tierra del Fuego managed to live under such terrible climatic conditions. But
that doesn’t mean that all human beings are alike. Those who live near the
equator have darker skins than people in the more northerly climes because
their dark skin protects them from the sun. White people who expose
themselves to the sun for long periods are more prone to skin cancer.”
“Is it a similar advantage to have white skin if you live in northern
countries?”
“Yes, otherwise everyone on earth would be dark-skinned. But white
skin more easily forms sun vitamins, and that can be vital in areas with very
little sun. Nowadays that is not so important because we can make sure we
have enough sun vitamins in our diet. But nothing in nature is random.
Everything is due to infinitesimal changes that have taken effect over
countless generations.”
“Actually, it’s quite fantastic to imagine.”
“It is indeed. So far, then, we can sum up Darwin’s theory of evolution in
a few sentences.”
“Go ahead!”