The Intelligent Cell (Origins)

by dhw, Friday, December 16, 2011, 14:40 (4724 days ago) @ David Turell

DAVID: And as for humans as a chosen species, we started with the chimps and bonobos with the same common ancestor. Each species could have advanced. Only we did. I can’t answer why [...]

Dhw: There’s nothing in nature to explain ANY such advances. Bacteria survived OK, and scientists would be delighted to find the most primitive form of life on Mars even without evolved species. So what was the need for greater complexity? Not being able to answer is hardly grounds for belief.

DAVID: Time today for a brief response to only this statement: "There's nothing in nature to explain ANY such advances": exactly!!!!! In my book I comment that bacteria have started life and have survived all the way. Why did evolution bother with complexification without the NEED to? There is obviously something that drives complexity in the genome, such as the newly-discovered epigenetics.

You’d used this as a reason for considering humans to be a “chosen species”, whereas I’m saying the fact that complexity was not needed is no reason for regarding humans as the original goal (pre-planning). It’s clear that something must drive complexity, simply because we have it, and epigenetics is an immensely promising development in our possible understanding of the mechanism. But the theory that a UI pre-planned the higgledy-piggledy comings and goings of evolution’s history seems to me no more likely than the theory that chance assembled the mechanism. And once you get on to pre-planning, you can scarcely avoid motive (is it possible to plan something without having a purpose?) and that takes you not only into the nature of the planner but also the status of the targeted end product. Out goes the neutrality of agnosticism and, “whether you like it or not”, in come the influences of the established religions you think you’ve left behind you!

However, I’m not sure that this will lead us very far, and there’s another point that I’d like to have your views on. You wrote: “[...] the human phenotype became smaller and weaker than the common ancestor, as judging by the chimp phenotype. And to make up for the weakness, the giant brain appeared.” One theory is that somewhere or the other (in Africa?) the forests disappeared and the common ancestor had to come down from the trees and start a new life on the ground. This would have entailed developing new skills. Is it not possible, then, that the process was the reverse of what you’ve outlined, and the need for new skills entailed developing the brain (much as certain exercises may strengthen and expand our muscles), as well as necessitating certain changes in the anatomy. This in turn entailed less use of other parts of the body, and so in due course the body became smaller and weaker as physical power gave way to intellectual power.

This idea puts us solidly in the field of epigenetics and Lamarckism, not to mention the “intelligent cell”, but it seems to me more convincing than random mutation, and I wonder if it isn’t also more tightly interwoven as a process than your suggestion that weakness led to brain power. Over to you, the scientist…