Dexterity and colour-vision in humans: advanced consciousness imposed on primitive anatomies

Homo sapiens is remarkably dexterous (https://www.merriam-webster.com/dictionary/dexterous).

However, the pentadactyl hand is so evolutionarily primitive that it differs little, anatomically, between humans and the first amphibians that crawled out of the primeval swamp (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5182414/ and https://www.perplexity.ai/search/in-which-amphibians-is-the-han-lkAhD_RER8OzYdHDcHBr.Q and https://www.perplexity.ai/search/how-many-digits-were-there-on-yUB3WAOzSB.iOWUVll7Kuw).

The crucial difference lies not in the hand but in the brain that operates the hand.

Similarly, Homo sapiens - unlike most mammals - enjoys colour-vision.

Like the pentadactyl forelimb, a retina replete with cones (https://en.wikipedia.org/wiki/Cone_cell) was probably already present in the first amphibians.

To this day, most reptiles exceed most mammals in seeing colours (https://www.perplexity.ai/search/which-class-has-more-colour-vi-150qLKxgQDeTIlIHzTo11A).

In the human mind, colours seem not merely to provide environmental information. Instead, we have a deep aesthetic (https://www.merriam-webster.com/dictionary/aesthetic) sense, which we assume to distinguish us from other animals - including even our closest relatives in the Hominidae (https://en.wikipedia.org/wiki/Hominidae).

Once again, the crucial difference lies in the neurological 'software', as opposed to the anatomical 'hardware'. Humans imbue colours with meanings - consider van Gogh (https://en.wikipedia.org/wiki/Vincent_van_Gogh) and Monet (https://en.wikipedia.org/wiki/Claude_Monet) - that could never occur to an amphibian.

It is the dexterity and colour-consciousness of Homo sapiens that have produced our technical and artistic prowess - which can seem almost divine, as opposed to a product of animal evolution.

The basic point of this Post is to correct an intuitive misconception, viz. that our bodies are as evolutionarily advanced as our brain. It is perhaps more correct to say that the human species - the most elevated species based on our success in the world - are most remarkable for how primitive we are anatomically.

However, there are two noteworthy caveats in this interpretation, as follows.

Firstly, humans are indeed anatomically unique in our upright bipedality and our extremely modified hindfoot. And it is this freeing of the forelimbs from the constraints of locomotion that has allowed the application of the hands to dexterity.

Secondly, the hand and the retina differ in their evolutionary history.

In the case of the hand, the entire ancestral lineage of humans, from amphibians through reptiles and mammal-like reptiles through primitive Mesozoic insectivores through early primates to monkeys and finally hominids, has remained consistently pentadactyl.

By contrast, in the case of the retina, there has been a 're-evolution' of something long-lost.

The earliest mammals, and the earliest primates, were presumably nocturnal, with retinas dominated by rods (https://en.wikipedia.org/wiki/Rod_cell), not cones. This loss of colour-vision, relative to their reptilian ancestors, persisted for tens of millions of years.

Cercopithecoid monkeys evolved perhaps 25 million years ago (https://www.perplexity.ai/search/how-many-millions-of-years-ago-xOFDy3HPS8qJ1MYIX.bCzw). It was only then that colour-vision, similar to that in humans, arose anew - in a sense reverting to a primitive anatomical condition.

Publicado el agosto 26, 2024 09:45 TARDE por milewski