0.6 billion years ago, 600 million years ago, we have complex multicellularity. Complex multicellularity, as opposed to simple multicellularity (because simple multicellularity is probably as old as life itself), because bacteria can form filaments that are essentially multicellular animals, structures. The curious thing people have explained to me is that the problem with complex multicellularity is that the organism has an inside and an outside, and the inside has to get oxygen. You have to transport oxygen to the inside of the organism, which is complicated, whereas the simple multicellularity that evolved early on essentially has only an outside because they are not really big structures. That gave rise to animals, to fungi, to plants, basically everything, and that was 600 million years ago.
You could ask, what's the other interesting thing that happened in the last 600 million years? There's one other thing that recently I would put in here because of my collaboration with Ed Wilson. This is the evolution of insect societies, which he would put into this slide at about 120-150 million years ago, because insect societies, or social insects, gave rise to a huge biomass. Wilson talks about two social conquests of Earth: the one caused by insects and the other one caused by us.
The other thing that happened in the last 600 million years of true great evolutionary significance, was the evolution of what I call “I”-life, and that I would equate with human language. Why is human language really out there with the origin of life, with the emergence of cells, and multicellularity? Because, in my opinion, it gives rise to a new type of evolution.
Up to this point, evolution is mostly genetic evolution. But suddenly, we have evolutionary processes that are not dependent on genetic changes. One person has an idea, we don't have to wait for a gene to spread in the population to spread this idea. It is the idea that spreads, and what transmits the idea is language. Language is somehow allowing now for more or less an unlimited reproduction of information, and that really defines us. You could say humans invented a new form of evolution, and that defines our adaptability and our success, maybe for the good and for the bad.