Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
Sex And Death
Bacteria reproduce by replication and mutate by conjugation. Mitosis ("the dance of chromosomes") is the process by which eukaryotic cells reproduce: the DNA of the new being is a combination of the DNA of the two parents. In eukaryotes the DNA is not just a string: genes are organized in chromosomes (a minimum of two, humans have 46).
Prokaryotes are wildly different from bacteria. But how did this striking difference between bacteria and their descendants come to be?
Mitosis is truly responsible for the origin of species. Before mitosis, bacteria were freely exchanging genes: the concept of "species" as we know them today did not exist, as any bacterium could mutate into a novel "species" at any time. Bacteria do not have true species.
On the other hand, multicellular beings cannot trade genes. Therefore they cannot mutate into anything else, and their offspring belongs to the same species (because both parents must be of the same species in order to interbreed) and such offspring inherits genes of the parents. Genes remain within the same family, the "species". Any multicellular being is a member of a species: it is an obvious fact, but a quite striking one. It is one of nature's whims. At the beginning of life on Earth, a new bacterium could be just about any combination of available DNA. Later in evolution, a new individual had to be a member of a species.
It may not be a coincidence that death was invented with multicellular sexual beings. They age and die, whereas bacteria did not.
Why did sexless and immortal bacteria evolve into beings that have sex and die?
Bacteria have only one sex, they can mutate (change their DNA), they can interbreed with any bacteria, they don't make children, and they never age or die. Animals that evolved from them have two sexes, they cannot mutate (cannot change their DNA), they can only inbreed within their species, they make children and they age and die. (Last but not least, the DNA of animals is organized and inherited in units called chromosomes, a detail that may turn out to be crucial to explain all of the above discrepancies).
Margulis argues that "death was the first sexually-transmitted disease". Once animals started aging and dying (once death had been programmed into their DNA), their offspring inherited the same disease.
Margulis' hypothesis is that, once upon a time, "eating and mating were the same". Cannibal unicellular beings may have merged into multicellular beings. The evolutionary advantages of this behavior may have led to sexual beings.
But the genders are exactly two, and each member of a gender has the same sexual organs. How did that happen?
Guy Murchie believes that death provides an evolutionary advantage: immortal beings that simply split would be immutable and easy prey to environmental changes. Death allows for regeneration of the race and for creation of new species. Death is a tool for change and progress. It is not a coincidence that the odds of immortality increases as creatures get more elementary.
Notwithstanding these cunning speculations, sexually-reproducing species are a bit of a mystery, and so is death, that came with sex.
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