Any more or less enlightened reader knows that evolution is the formation of more complex organisms from simple ones and the development of living things on the planet from the very beginning of life. Do you think that the source of development and complication is in training and striving for improvement (J.B. Lamarck) or in the struggle for the existence and victory of the fittest (C. Darwin), in the ability to help each other (P.A. Kropotkin) or catastrophes of large and not very (J. Cuvier) - not the point. The main thing we all think about, what is the role of chance in evolution: species, classes and humanity as a whole? What is the random occurrence of each of us? And an accident or a regularity?
Classic theory
Modern science proposes to consider the theory of evolution in the context of accumulated knowledge, using the rules of the synthetic theory of evolution. Arose on the basis of Darwinism, supplemented by the knowledge of molecular biology, embryology, paleontology, genetics and so on, we are offered the whole spectrum of knowledge that can be put into the accepted classical triad of “heredity - variability - selection”. At each step of it, what is the role of chance in the evolution of species?
Modern biology
Today, a professional botanist will not break into the jungle of molecular biology, and an ecologist is unlikely to intelligibly explain the specifics of human embryo development. And each narrowly focused biological science will answer the question of what role of chance in the evolution of species from its point of view. Let’s try to understand the classical triad from the general standpoint of popular knowledge in biology, which most non-biologists have remembered from school.
Heredity: What is the role of chance in species evolution?
Everyone remembers: inheritance of traits determines the gene set. Genes are in the DNA strand. Chromosomes are made of DNA , chromosomes are in the nucleus. In any organism that reproduces sexually, the set of chromosomes is diploid (2n), which during the formation of gametes is halved (n).
Where is the accident? The answer is everywhere. About mutations (random changes) that can change one gene or much later. Chromosomes exchange random sites (crossing over), and when chromosomes separate during meiosis (gamete formation), this discrepancy is completely random. Well, when merging gametes with the formation of a zygote, the role of chance is colossal in general.
And if today artificial embryology has undergone the development of artificial insemination and operations in the first stages of embryo ontogenesis, how soon will randomness cease to affect hereditary gene transfer?
What is the role of chance in species evolution: variability
The fundamental quality of life, the ability of all living things to acquire new qualities and, as a result, increase adaptability to changing environmental conditions. The basis of variability, important for evolution, is a change in genetic material. And the main thing here is mutations. Spontaneous or under the influence of mutagens, point or change the number of chromosomes in the genome - all of them, by definition, are not useful for a particular individual. Neutral at best. But with some kind of change in the environment, it is such an accidental breakdown that will become a key factor in determining the most adapted organisms.
And if it is proved that even stress can become a mutagenic factor, what can we say about global environmental pollution by half-life of nuclear energy?
Natural selection - embodied chance in the evolution of species
From the formation of the zygote to puberty, natural selection, like the sword of Damocles, hangs over all living things. A zygote can never become a baby simply because they ate their mom. And this is the most harmless thing that can happen. A coincidence - in the eruption of the lava of the volcano and the separation of the population in two, or the fall of coconut into the ocean and getting it on a remote island, where it can give rise to a new population or not.
The struggle for existence in its most severe form - intraspecific - makes the shark embryo eat its brothers in the womb. And the interspecific struggle will cause the blind cuckoo to throw the eggs of the adoptive parents from the nest.
And yet, what is the answer?
The answer to the question of what is the role of chance in the evolution of species, despite the apparent obviousness, is not so simple. Ask the theoretician of mathematics - and in the formulas and logarithms he will prove that there is nothing random in the world. Everything is probable and the degree of probability is quite predictable.
Our knowledge in the field of electronic physics and long-range astronomy has led mankind to a bifurcation point in science. A huge store of knowledge with new discoveries can turn us in a completely unpredictable direction, as, for example, Krasin’s pipes are fantastic “rat-holes” of space-time, which advanced cosmonautics are seriously interested in when they are looking for supersonic ways of intergalactic travels.