Life’s Genesis and Evolutionary Mechanisms

Oparin’s Theory

Approximately 4 billion years ago, the components of Earth’s primitive atmosphere reacted due to the energy of storms, solar radiation, etc. As a result, simple organic molecules were created.

1. The Earth cooled down, intense rain was produced, and seas were formed. These molecules accumulated in these seas. Oparin referred to these seas as primordial soup.
2. The organic molecules started to join, creating bigger ones. Some of them were isolated in coacervates.
3. Some coacervates developed molecules (nucleic acids) in their interior that were capable of self-replicating. These were the first organisms and the origin of all cells.

Present-Day Hypothesis

One of the possible places in which living things could have first appeared are deep-sea hydrothermal vents. According to some scientists, these places release inorganic matter that, along with water and CO2, formed the first molecules. The energy needed could have come from the oxidation of reducing agents, such as hydrogen sulfide.

Mechanisms

According to this, there are two mechanisms:

• Self-replication: The ones that were able to self-replicate (possibly RNA) and that were surrounded by a lipid layer were formed, creating the first prokaryotic cell.
• Metabolism: Lipid bubbles that were able to carry out chemical reactions were formed and later developed the ability to self-replicate.

Australian stromatolites that are over 3.6 billion years old suggest they belonged to cyanobacteria, photosynthetic organisms responsible for the existence of oxygen in the atmosphere.

Fixism and Evolution

1. Evolutionary processes are slow and cannot be observed in one human life.
2. There was no understanding of genetics, so it was difficult to understand, for example, how new characteristics appear.
3. In those times, defending an evolutionary theory meant confronting religious doctrines.

Anatomical and Morphological Evidence

1. Homologous organs: Organs that, although may perform different functions, have the same evolutionary origin and share an identical structure. They are proof of divergent evolution, which refers to the changes caused by habits or the environment.
2. Analogous organs: Organs that perform the same function even though they have different evolutionary origins. They are proof of convergent evolution, which refers to the changes that create similar structures in groups of living things that are not related at all.
3. Vestigial organs: These are the ones that disappear because they are not useful. They are proof that they were important for ancestors, but with time and because of changes in the environment, they tend to disappear because they stopped being important.

Lamarckism Theory

It still has good ideas:

1. It acknowledges an evolutionary process and proposes a mechanism in order to explain it.
2. It recognizes the relationship between anatomical structures and their purpose.
3. It explains that organisms adapt to the environment they live in.

And then some mistakes:

1. He claimed that characteristics are transmitted from parents to offspring.
2. He claimed that animals have an internal need to improve themselves and become more complex.

Darwinism

1. The individuals that make up a population of living things have a wide variety of anatomical, physiological, and behavioral differences.
2. More individuals are born in each species than the number that reach reproductive age.
3. Competition between individuals of a species for space, food, and procreation. This is known as the struggle for existence.
4. Individuals whose characteristics help their survival in a certain environment are favored over the ones who are badly adapted. This is referred to as natural selection.
5. When the surviving individuals reproduce, the more favorable characteristics are transmitted to the offspring.