This book which came out in 2016 bears the full title: "Other Minds: The Octopus, The Sea and The Deep Origins of Consciousness. I especially found interesting the account in the second chapter of how multi-cellular animals may have arisen from single cells. It begins with the following chronology which is itself mind boggling.
The Earth is about 4.5 billion years old, and life itself began perhaps 3.8 billion years ago or so. Animals arrived much later - perhaps a billion years ago, but probably some time after that.
There are extensive foot notes at the back of the book but I didn’t find a discussion of how exactly the 3.8 BYA date was arrived at. I don’t think of single cell animals as leaving much of a trace but I expect they may have produced a compound of some kind which can be dated, perhaps. (Anyone know?) But I did find this in the foot notes for that passage which was interesting:
The date at which it is thought to be pretty clear that life existed is 3.49 billion years ago, so life evolved before that time. Life need not have begun with cells, but cells too, are thought to be very old.
I do note that the authors seem to use “evolved” in a way we often say is not what the theory of evolution is about. But it does seem a natural extension of the term to speak of a transition from complex chemical processes going on outside of life (but now found only within life) evolving into forms we would describe as life. I tend to think of life as being distinguished by a capacity to replicate itself. Just to be sure, I googled “life” and found: “the condition that distinguishes animals and plants from inorganic matter, including the capacity for growth, reproduction, functional activity, and continual change preceding death”.
Interesting read so far and one I suspect would interest a lot of you who are more educated in science than I am. Has anyone already read it?