From Guy Cox
David Holdsworth argues that extraterrestrial life is unlikely because life on Earth “descended from a single ancestor cell” despite an abundance of suitable habitats (18 May, p 28). This is misconceived.
Firstly, life as we know it descended from not one but two cells – the proto-archaean, which provided the host cell, and the proto-eubacterium, which provided some organelles such as mitochondria. Then there are viruses. While not getting into the debate as to whether viruses are alive, there is no doubt about their contribution to evolution.
Sydney, Australia
