There is the implied assumption that divergent evolutionary traditions eliminate convergent features. I am of the opinion that despite divergent traditions, some features may converge if there is a common ancestor, and the feature has a large enough survival potential.
Where this comes in, is the question of consciousness of invertebrates specifically the cephelopods. While we can argue about the consciousness of vertebrates, there has been some question as to the higher invertebrate brains, that is as a default against them being conscious.
The assumption is that because they have spent so long as a divergent tradition evolutionarily speaking, there is no room for convergent evolution.
If my counter assumptions are correct, an early invertebrate ancestor to both vertebrates and invertebrates may have created a common convergent trend that has reached over a significantly large period of time to give both cephalopods and vertebrates the potential to be conscious. However this flies in the face of conventional wisdom about divergent evolution, so I ask the question, is it out of range to ask whether the afforementioned assumption is accurate? What is your opinion?
Dear Dr.Smith,
I think the assumption makes sense. However the ultimate ancestor of all cellular organisms might have been the same and the basic metabolic/biochemical pathways even in unrelated and distant organisms remain the same.
Hope the papers mentioned below may give some info. on the specific issue.
1.Big ideas for small brains: what can psychiatry learn from worms, flies, bees and fish&quest,T Burne, E Scott, B Van Swinderen, M Hilliard… - Molecular …, 2011 - nature.com.sci-hub.org
2.Comparison of ongoing compound field potentials in the brains of invertebrates and vertebrates,TH Bullock, E Başar - How do Brains Work?, 1993 - Springer
Best regards
Thankyou Dr. Achankunju I was of course looking for a much more recent ancestor but your point is taken. I have to work on the phrasing of the question more. Currently I am working on the theory that it was the development of the roof of the midbrain that presages consciousness, so I am not terribly interested in worms, although flies, bees, and fish might have something to say. I am of course interested in the formation of the ganglion type brain. Some time after our ancestors gave up radial symmetry for bilateral symmetry.
I wonder if you are over-attributing a 'conventional wisdom' about his, Graeme. As far as I am aware most biologists would accept that convergent evolution is both possible and commonly occurring. Penguins and auks have converged. Binocular vision has arisen many times, as of course have eyes. And I am not sure you need to require anything particular in the ancestry. Colonisation of the air occurred in many animal groups from an ancestral stock that never flew.
In brain terms the work by Murray Shanahan is interesting - comparing birds with mammals. ALthough birds do not have a cortex like ours certain birds like corvids have developed skills that only otherwise seem to occur in primates - tool using and language skills for instance.
From a basic theoretical genetics point of view I cannot see why there should be any rules about this. DNA can randomly mutate however it likes and gene products can achieve convergent functions in all sorts of ways. Just as with enough time and monkeys typing you will get one monkey typing out Hamlet, with a bit more time you will get another monkey typing Hamlet in French. And survival pressures can only help convergence since a good trick is a good trick however you achieve it - is it not?
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