Those are some of the things that molecules do, given four billion years of evolution.
There are so many plants on the Earth that there’s a danger of thinking them trivial, of losing sight of the subtlety and efficiency of their design. They are great and beautiful machines, powered by sunlight, taking in water from the ground and carbon dioxide from the air, and converting them into food for their use and ours.
Every plant uses the carbohydrates it makes as an energy source to go about its planty business. And we animals—who are ultimately parasites on the plants—we steal the carbohydrates so we can go about our business. In eating the plants and their fruits, we combine the carbohydrates with oxygen which—as a result of breathing—we’ve dissolved in our blood. From this chemical reaction, we extract the energy which makes us go. In the process, we exhale carbon dioxide into the atmosphere, which the plants then use to make more carbohydrates. What a marvelous cooperative arrangement! Plants and animals each using the other’s waste gases; the whole cycle powered by abundant sunlight. But there would be carbon dioxide in the air even if there were no animals. We need the plants much more than they need us.
We are, each of us, a multitude. Within us is a little universe.
In the future we might well be able to put nucleotides together in any desired sequence to produce whatever human characteristics we think desirable. A disquieting and awesome prospect.
Similar chemical reactions must have occurred on a billion other worlds in the Milky Way galaxy. Look how easy it is to make great globs of this stuff! The molecules of life fill the cosmos.
