- Why would something like photosynthesis evolve on Earth? Early life apparently couldn’t handle UV radiation. Does that sound like space life?
- The genetic clock idea is too simple. Some early life was probably more complex than the slimmed down super-evolver bacteria we have today. Earth might be rare because cells with heavy genomes, like ours, managed to not get wiped out by their more efficient relatives.
- 500 million years later is not immediately after the Earth formed. That’s a long time.