Biologists, who understand neurons, still haven't a clue how the brain does what it does. Physics operates by universal laws, biology by whatever works at the time. Now 93, an emeritus professor of zoology at Harvard, he collaborated on the ''modern synthesis,'' the combination of genetics and Darwinism that is the standard theory of evolution. But because physics is several centuries older than biology, it remains the basis for people's expectations of what science is and isn't. Biology, a young science that developed in the 19th century, is observational, describing a molecule's composition, a protein's structure, a species' characteristics.
Gravity holds it in orbit.
As a result, causes end up being combinations that usually include chance. So maybe a meteorite hit Earth and raised enough dust to cool it long enough to kill some species. Mayr's book is a long essay on how biologists study living things on the large scale of organisms and their families. Its range is enormous. It begins by distinguishing life from nonlife.