| Popis: |
The 20th century has been characterized, among other things, as the century of science and technology. Aside from important discoveries made during this century, three of the major concepts and areas of knowledge that have acquired singular preeminence are the Universe, Life and Man. In the last century Charles Darwin quite successfully applied the concept of evolution by natural selection to living creatures. In more general terms the concept of evolution by natural causes can be applied to the inanimate world and to the Universe as a whole including all the cosmic bodies, namely galaxies, stars, circumstellar and interstellar clouds, chemical elements, interstellar molecules, planetary systems, planets, comets, asteroids, meteorites, etc. It is within this context that we can speak of cosmochemical evolution and its presumed relation to the origin of life on the planet Earth. More specifically, in this paper, we will focus our attention on the origin and evolution of life and we will briefly cover the pertinent physical and chemical aspects of cosmic evolution which were responsible for the formation of the main biogenic elements in stars, which aside from H include C, N, O, S and P; and the circumstellar and interstellar organic and other molecules which constitute the dust and gas clouds of the interstellar medium. We will discuss the formation of both the Solar and the Earth-moon systems, the role of comets in providing the water and the biogenic precursors necessary for the formation of biochemical compounds on the early Earth, the probable processes of chemical evolution that presumably preceded the emergence of Darwin’s ancestral cell from which all other living systems have evolved on the Earth, including this chimerical and probably ephemeral creature we call Homo sapiens sapiens. |
