Seeing Emergent Physics Behind Evolution


Jordana Cepelewicz interviews Nigel Goldenfeld in Quanta:

Physics has an underlying conceptual framework, while biology does not. Are you trying to get at a universal theory of biology?

God, no. There’s no unified theory of biology. Evolution is the nearest thing you’re going to get to that. Biology is a product of evolution; there aren’t exceptions to the fact that life and its diversity came from evolution. You really have to understand evolution as a process to understand biology.

So how can collective effects in physics inform our understanding of evolution?

When you think about evolution, you typically tend to think about population genetics, the frequency of genes in a population. But if you look to the Last Universal Common Ancestor — the organism ancestral to all others, which we can trace through phylogenetics [the study of evolutionary relationships] — that’s not the beginning of life. There was definitely simpler life before that — life that didn’t even have genes, when there were no species. So we know that evolution is a much broader phenomenon than just population genetics.

The Last Universal Common Ancestor is dated to be about 3.8 billion years ago. The earth is 4.6 billion years old. Life went from zero to essentially the complexity of the modern cell in less than a billion years. In fact, probably a lot less: Since then, relatively little has happened in terms of the evolution of cellular architecture. So evolution was slow for the last 3.5 billion years, but very fast initially. Why did life evolve so fast?

[The late biophysicist] Carl Woese and I felt that it was because it evolved in a different way. The way life evolves in the present era is through vertical descent: You give your genes to your children, they give their genes to your grandchildren, and so on. Horizontal gene transfer gives genes to an organism that’s not related to you. It happens today in bacteria and other organisms, with genes that aren’t really so essential to the structure of the cell. Genes that give you resistance to antibiotics, for example — that’s why bacteria evolve defenses against drugs so quickly. But in the earlier phase of life, even the core machinery of the cell was transmitted horizontally. Life early on would have been a collective state, more of a community held together by gene exchange than simply the sum of a collection of individuals.

More here.