From Alex Saragosa
The explanation that an asteroid started the evolution of multicellular life 580 million years ago instead of an extreme ice age looks to me, if not wrong, at least useless (3 May, p 17)
Surely tens of asteroids as big as the Lake Acraman one, or even bigger, struck Earth in the billions of years preceding that particular impact, but in all the other cases life continued its quiet unicellular evolution. So to think that the Lake Acraman asteroid started the evolution of multicellular life simply shifts the problem.
Instead of asking “Why did multicellular life start to evolve around 500 million years ago?” we should ask: “What particular conditions were there on Earth 580 million years ago that allowed the Lake Acraman asteroid to start the evolution of multicellular life?”
Terranuova, Italy
