Understanding Prebiotic Synthesis and Evolutionary Theories
Prebiotic Synthesis
The prebiotic synthesis: after the experiences concerning the Pasteur problem of the origin of life, which has taken more than 60 years, was addressed anew in 1920. A new version of spontaneous generation was devised, applicable at the beginning of the progressive association of life. This involves the origin of simple inorganic molecules to form more complex organic molecules through the condensation of simple molecules.
Organic formation occurs within the “soup” of molecular aggregates as small droplets or coacervates.
Reinterpretation of Prebiotic Synthesis
The reinterpretation of prebiotic synthesis hypothesizes that the most current information on the origin of life is based on the existence of biomolecules as prerequisites for the origin of the earliest organisms. Critics argue that the primitive atmosphere was not reductive; it was assumed that if an experiment is repeated in a less reductive gas, worse results would be obtained. A “soup” that is too diluted will not allow the condensation of monomers to form polymers.
Submarine Hydrothermal Vents
In these sources, resulting from volcanic activity, hot water drags many minerals in a reactive oxygen mask on its way out.
Evolutionary Theories
Evolutionary theories propose that current species descended from common ancestors and continue to change over time.
Fixism
Fixism is a belief that holds that existing species have remained essentially unchanged since creation. Therefore, species are considered immutable, as they were highly regarded as created. Naturalists who defended fixism include the Swedish botanist Carl Linnaeus, the naturalist Georges Cuvier, and some naturalists like Georges Leclerc.
Lamarckism
Lamarckism is based on the idea that organisms necessarily change over time, a process that happens continually and gradually. More complex changes in environmental conditions over time cause species to alter their habits, and these changes would be transmitted to their descendants, leading to an entire population changing over time.
Critique of Lamarckism
Critics of Lamarckism argue that there is no evidence that agencies drive transformation and that changes towards complexity occur. Current knowledge about the inheritance of traits denies the possibility that body modifications acquired over an individual’s life through use or disuse are transmitted to offspring. Only those traits whose information lies in the genes are inherited.
Theory of Natural Selection
The theory of natural selection states that variations are heritable differences between individuals in a population. Darwin observed that living beings are born with variations that can help them survive in a struggle for survival against limited resources. Some hereditary variations provide individuals with advantages compared to those who lack them, allowing them to survive and leave descendants.
Darwin and Mendelian Inheritance
The main difficulties in defending Darwin’s ideas stemmed from ignorance of the laws of inheritance, which Mendel later proposed. This created a challenge in resolving the relationship between natural selection and the use and disuse of organs, leading to criticisms from the perspective of mixed inheritance.
Synthetic Theory
The synthetic theory posits that the evolutionary unit is the individual, not the population. Differential reproduction is the mechanism through which the joint action of genetic variability and environmental pressure produces selection. Evolution occurs through gradual changes in the genetic makeup of species.
Neutral Theory
The neutral theory suggests that many changes occurring in DNA are neutral concerning natural selection, and the proteins have little or no effect on molecular functions. Chance, rather than natural selection, determines variations.
Discontinuity Theory
This theory proposes a rejection of the idea put forward by the synthetic theory that the transition from one organizational plan to another is gradual. Instead, new species emerge during moments of evolutionary explosions, followed by long periods of stability in which species remain constant.