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View Full Version : Before human civilisations, before animal hierachy, the cellular kingdom...



Maciamo
22-08-06, 00:33
Modern biology divides all life beings into six kingdoms within 2 empires. The first empire, the prokaryotes ("pre-nuclear life beings") is composed of 2 kingdoms : eubacteria and archeobacteria. The 2nd empire, the eukaryotes (nuclear cells) is split in 4 kingdoms : protists, fungi, plants and animals.

Evolution is a process in which life organisms have generally got more complex with time. Early life beings were primitive monocellular beings without a nucleus. Some managed to acquire a more complex organisation within their membrane. According to the endosymbiotic theory (http://en.wikipedia.org/wiki/Endosymbiotic_theory), some primitive prokaryote cells absorbed other similar cells, and merged into a new symbiotic cell instead of having the smaller cell being digested by the bigger one.

Organelles like the mitochondria would originally have been independent cells with their own DNA (which they still have), but have lost the genes necessary to survive outside the bigger cell. I like to think of them as having become the "slaves" or "subjects" of a more powerful cell. Each organelle has acquired a specific task or "job" with the host cell. In eukaryotes (like human body cells), some cells can contains hundreds of thousands of mitochondria (let alone other "submitted" organelles), creating a real kingdom of "subject cells" working for the survival of the host cell. Could this have been the first "organised society" in the evolution of life beings ?

It has been suggested that a colony of bees or ants are in fact a single organism, just like a body composed of billions of cells. A single bee (or ant) cannot survive on its own. It needs the colony, and indeed works and die for the colony and for the queen. All workers, be it for bees or ants, share the same DNA. They are clones. In that respect they are also like the cells of a larger animal. This is why bees will sacrifice themselves to protect the group. No other animal would do that. But the cells in our body do it all the time to fight viruses or other foreign bodies.

We may not be aware of it, but human society is also like a macro-organism of its own. It wouldn't exist without the contribution of millions of individuals. A single human cannot accumulate all the human knowledge necessary to recreate all our technology if he or she was the only survivor of a mass extinction. In that respect we are like no other animal. Modern human society is not just a grouping of millions of humans, but much more than that. Not everybody contributes to social and technological progress (only a minority does if we consider the high illiteracy of poorer countries or lower social classes), but without those people who pass on and augment the "shared human knowledge" our society could not survive as it is nor progress.

Mayama
04-03-19, 14:12
It was very helpful!
Thanks!