I think it's helpful to look at a timeline of life on Earth when thinking about that issue. http://hopefullyintersting.blogspot.com/2018/03/the-drake-equation-

I think it's helpful to look at a timeline of life on Earth when thinking about that issue. http://hopefullyintersting.blogspot.com/2018/03/the-drake-equation-again.html http://hopefullyintersting.blogspot.com/2018/03/the-drake-eq... Life's gone through a lot of changes over the time it's around. 10,000 years ago there were already humans and the Neolithic revolution was well underway and agriculture was just starting. Multicellular life was one of the big revolutions but eukaryotes and before that photosynthesis seem to have taken a very long time to evolve. Interestingly we don't have a lower bound for how long it took life to arise once the Earth's surface started having liquid water, so maybe very simple life is pretty common.