The Nature of Consciousness

Piero Scaruffi

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These are excerpts and elaborations from my book "The Nature of Consciousness"

The Tree Of Life

As geneticists have been rearranging the tree of life based on the DNA or organisms, one thing has become evident: life diverged first into bacteria and archaea, eukaryotes then evolved from archaea but with a little help from bacteria. Somehow eukaryotes acquired genes from bacteria, genes that were critical for their metabolism. This implies that genes are passed not only vertically from generation to generation but also horizontally (or "laterally") from one species to another. This lateral gene transfer could turn out to be the single most important factor of evolution. The more we study their DNA, the more eukaryotes appear only distant relatives to their archaea ancestors, the more they appear the product of a large number of lateral gene transfers. There was probably a time when swapping genes among cells was an ordinary event: by swapping genes, cells would simply trade or share skills with other cells.

Research carried out, among others, by the US biologist Carl Woese is showing that the phylogenetic tree looks more like a web than a tree ("Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya", 1990). By drawing the family tree of today's genes, one should eventually find the genetic content of the common ancestor of all life. Instead, different genes yield different family trees. If they all had forebears in a common ancestor, it must have been a terribly complex being, far from the simple living cell that one expects. It is more likely that some genes were transmitted horizontally (one lineage to another) as well as vertically (one generation to the next one) in the tree. If gene exchanges were common, one can envision a colony of cells as the ancestor of all life and gene exchanges as the main form of early evolution.

 


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