Fascinating account of how multicellular animals arose in Other Minds by Peter Godfrey-Smith


(Mark D.) #1

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?


(George Brooks) #2

@MarkD

Is this the book that invests some time in showing how alien octopus eggs could have survived interstellar travel, and transmitted their very alien DNA to Earth’s life forms?


(Mark D.) #3

I’m pretty sure it is not. Just straight science without any axe to grind regarding religion one way or the other.

It is pretty interesting how control of its arms is distributed without any central processing. It talked about sponges likely being the early form which led to the animal kingdom since the larvae form (if that is what you call it) is free swimming. Also pretty interesting to see how some basic needs of multicellular animals evolved first between individual single cell creatures.

The first multi-cell creatures were more like colonies of creatures than individual multi-cellular ones. But what really blows my mind is how DNA for each individual cell would eventually become consumed in the DNA of the larger creature. Breath taking.


(George Brooks) #4

@MarkD

You are absolutely right… a science book… here’s a preview link to Google Books… (generally, preview links only let you read certain chapters… but it’s a pleasure to have it so accessible to get a taste of it!).

https://books.google.com/books?id=SZ8sDAAAQBAJ&printsec=frontcover&dq="Peter+Godfrey-smith"+octopus+minds&hl=en&sa=X&ved=0ahUKEwjOktjH9OjbAhVm54MKHSDnBeEQuwUIOTAD#v=onepage&q=Contents&f=false


(Matthew Pevarnik) #5

Here’s a recent discussion in Nature:
https://www.nature.com/news/oldest-traces-of-life-on-earth-may-lurk-in-canadian-rocks-1.22685

You are very astute! Stromatolites are pretty big and made my single celled Cyanobacteria:


(Mark D.) #6

Thanks for the reference. Pretty surprising that rock can even be found that is so old. I think of plate tectonics as continually stirring the crust back into the mix. But I suppose the crust is on top because it is lighter and while some of it does get subducted in places apparently there are areas which escape the stirrer.