Life on Earth has been shaped by Darwinian principles. As we know it today, life is controlled by the DNA. DNA pervades all cells of living bodies, whether animals or plants. Life started about 3.5 billion years ago with simple cells and probably some kind of RNA or even less-sophisticated information retention abilities. The evolution of life is staggering. One big step is the start of collaboration between several cells to form a superior entity. Multicellular organisms appeared quite late, probably only two billion years ago.
Darwin and its Origin of Species, then the discovery of DNA as the repository of life information, have put the theory of evolution on very solid grounds. Life on Earth is evolving means that gradual changes have appeared that make all living species be adapted to their environment. Two ingredients are necessary: the randomness of the infrequent DNA mutations, and the natural selection process that invariably filters out the unadapted ones.
The human species has nothing special in that respect and is completely relevant to life of Earth. It is just the end of a non-peculiar twig in the evolution bushy tree.
It is just one species. One species alive today. However, the speed of evolution is limited by the generational renewing. At least a hundred generations are needed to see a new trend appearing. For example, the lactose-tolerant adults in Europe appeared only after several thousand years of selective pressure.
We posit that this second evolution is being swamped by a new one, simply because the third evolution is going much faster. More on that later.
