In HG Wells' War of the Worlds, the Martian invaders were defeated by this most modest warrior - the common cold. Could the reverse happen and alien viruses could pose a threat to human astronauts when they land on Mars? This intriguing question is asked by Dale Griffin in a new article for the journal Astrobiology, which also asks if our first evidence of extraterrestrial life could take the form of viruses.
It is not known whether they are alive or dead. Or where exactly did they come from. One thing is certain, however - they have been a gigantic success in the evolutionary race. Therefore, Earth is a planet of viruses.
In biology lessons, many of us were not taught how much viruses affect, for example, the Earth's climate and the appearance of our planet, and how they shape the evolution of all organisms present on it. That they are so numerous and ubiquitous that one might even wonder if the Earth is not primarily their planet. In addition, they can be witnesses of the oldest times, when life germinated there only about 4 billion years ago. And that they are still a great mystery for science, which is unable to give a clear answer to a seemingly simple question: are they living beings or just chemically complex but dead matter? Here is the history and secrets of some of the most fascinating and deadly creatures that evolution has ever produced.
Another theory assumes that viruses were once unicellular organisms that "came up with the idea" that you can get rid of all unnecessary cellular baggage and stop caring, for example, about food and metabolism, and still achieve evolutionary success - that is, effectively duplicate yours genes .
Today, viruses kill trillions of microorganisms, thereby releasing gases into the atmosphere that reflect solar radiation. So they indirectly influence the Earth's climate.
And how many of them are there on Earth at all? The number 1031 (or 1 with 31 zeros) appears most often in the scientific literature!
Everyone had some plans for 2020. Memes are bitter, but summarize them accurately. After all, most of us now wish that this year just didn't happen. International conflicts and the coronavirus pandemic have changed lives around the world. That's why the whole world is now ironically laughing at what the clash looks like: plans for 2020 vs. reality. You know who is losing in it;) See for yourself!
The functional definition of life consists in establishing a list of axioms that do not refer to its structure, which every organism must fulfill in order to be considered alive. He must (one of the possible axiomatizations, although they all mean more or less the same):
be able to reproduce;
show hereditary variability that affects reproductive capacity, that is, be capable of evolution.
Thus, crystals, prions or computer viruses, although capable of replication, do not have any significant hereditary characteristics and are therefore not alive. Biological viruses, memes, pre-cellular life on Earth, and possible alien life on other planets are alive by this definition.
Structural definition of life consists in establishing a list of criteria referring to the structure of an organism. These include:
multiplication
increase
metabolism
cell structure, with ribosomes and other organelles
genetic material stored in the form of nucleic acids
occurrence of proteins and nucleic acids
movement
Due to the organization of the genetic material, viruses are divided into:
RNA-viruses (including retroviruses)
DNA-viruses
Some known viruses:
flu
HIV (causing AIDS)
Heine-Medin disease virus
Sheep jump disease virus
Ebola virus
dengue virus
Herpes virus
measles virus
HAV, HBV, HCV
Reference:
4:10–4:40 | Astrovirology – What’s missing? | Ken Stedman (Portland State University, USA; kstedman@pdx.edu) | 20/10