There could have been many "crafty" ancestors

There could have been many "crafty" ancestors
There could have been many "crafty" ancestors
Anonim

Biologist Alexander Markov believes that perhaps the common ancestor of all life on Earth was not only LUCA, but the community of microorganisms.

microorganisms

Alexander Markov, however, is not the only scientist who is more inclined to believe the version about the community. The same hypothesis, for example, is adhered to by the largest microbiologist and academician Georgy Zavarzin.

“They (scientists who are inclined to the idea that“in the beginning there was a community”, and not the only original species - NS) proceed from the fact that the stable existence of the biosphere is possible only if biogeochemical cycles are relatively closed, otherwise, living beings they will use up all resources very quickly and poison themselves with the products of their own vital activity,”Markov writes in his book“The Birth of Complexity. Evolutionary biology today: unexpected discoveries and new questions."

Thus, closed cycles, according to some biologists, can only be provided by groups of different types of microorganisms that have shared biogeochemical functions. That is, some organisms in this case will use the resources of the environment and fill it with the products of their vital activity, and the latter will use the waste products of the former, and return the original resource in the form of their waste to the environment. The communities that are able to form such a closed cycle are, for example, one of the most ancient microorganisms on Earth - cyanobacterial mats. According to Zavarzin, an organism that alone is capable of closing such a chain simply cannot exist, just as a perpetual motion machine cannot exist.

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“For the stage of chemical pre-life, this is even more obvious,” writes Markov. - No single organic molecule can sustainably reproduce itself and maintain homeostasis in the environment. Only complexes of a fairly large number of different molecules are capable of this, between which “mutually beneficial cooperation” (symbiosis) has been established”.

So Luca, indeed, could not be the only species of microorganisms, but a polymorphic community, which actively exchanged hereditary material between its "individuals". According to Alexander Markov, the original properties of life on Earth include diversity, symbiosis, information exchange and separation of functions.

Nevertheless, the author also says that there are exceptions in biology. Within the framework of theory, the only species of microorganisms that lives on the planet for a very long time can still be imagined. For example, it can feed on some substances that come from the earth in small quantities. Waste from its vital activity can be processed by geochemical processes (simply buried in the earth's interior) - living things may not participate in this. As a result, such a microorganism will simply integrate into the already existing geochemical cycle, only accelerating it.

“However, in general, today the statement“in the beginning there was a community”seems, in my opinion, more probable than“in the beginning there was one kind of microbes,”Markov writes.

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