Recent xenobiology came back into the discussion. Xenobiology (as the Greek name says) represents extraterrestrial origin (alien) of life. This involves not only the insemination of the earth by some aliens clever, but especially the appearance in extraterrestrial space of some simple life forms.
Xenobiology (astrobiology in this case) seems believable up to a point, in the sense that complex molecules are likely to form in extraterrestrial space, which exists in living matter, for the simple reason that atoms are more likely to meet. Under the influence of cosmic radiation this becomes even more possible. Indeed, synthesis in extraterrestrial space might explain chirality. I mean for example, amino acids in living organisms are levorotatory, and monosaccharides are not dextrorotatory. Chirality (comes from the hand, related to palmistry) refers to images that do not overlap their mirror image. In the case of laboratory organic synthesis, the ratio of the isomers is of 50%-50% (racemic mixture). It seems, however, that in space the ratio of levorotatory/dextrorotatory amino acids is 3/1. However, there are alternative explanations for this.
I personally believe that it is possible that certain larger or smaller "bricks" appeared in space, but life as such appeared on Earth. What I rely on? Admittedly, those aforementioned bricks are quite difficult to synthesize, and sometimes the conditions on earth during the period in which we considered life to have appeared were not exactly conducive to these syntheses, but life is more than those bricks. It is a more or less rapid exchange of substances, enzymatic reactions. And for that you need a certain temperature. That's why I think we can talk about very interesting extraterrestrial syntheses, but of life, if it is not associated with a planet with a certain temperature, Less.
The study of structures that appear on the surfaces of some meteorites has suggested the existence of alien bacterial fossils. It's probably something else, they are probably contaminations with terrestrial life, as suggested, as happened a decade ago with the announcement of life on Mars. But it's good that studies and ideas about the origin of life have re-entered the discussion. repeat, I think the mechanisms by which life arose and then evolved must have something in common, and therefore they should not be studied separately. Evolution and abiogenesis they don't have to be totally separate.
