> I think it's not unreasonable that we are sort of early to the party. Earth has existed for about 1/3 of the lifetime of the universe Universe begins

> I think it's not unreasonable that we are sort of early to the party. Earth has existed for about 1/3 of the lifetime of the universe Universe begins | 9.2 billion years Earth formed | 0.5 billion years First life | 0.5 billion years First photosynthesis | 3.0 billion years Enough oxygen in air for macroscopic life | 0.5 billion years Now The main work was: (1) Supernovas creating heavy elements. At first, the universe is all hydrogen (and helium). It takes some generations of stars forming, and exploding as supernovas to create and spread around heavier elements, so that a planet like Earth can form, with all the minerals we have. Do we need 9 billion years for this, or could there have been planets with heavy elements, how much earlier? Is Earth among the first possible? (2) It took 3 billion years of photosynthesis, by single-cell microbial life, to produce and accumulate enough oxygen. First the oxygen released into air would go and oxidize the minerals on Earth's surface. Only after the whole rocky surface was oxidized, would oxygen start to accumulate into the atmosphere. Somewhere around 10% or 13% atmospheric oxygen, it was enough that also other than flat, single-cell-layer multicellular macroscopic life could start to form, without the inner cells being starved of oxygen. 3 billion years of repetitive, grunt work by the microbes. (Then it took 0.5 billion years of evolution from the Cambrian evolutionary explosion, to humans.) Compared to these two, the other steps took much less time.