The Scientific Basis of Life's Evolution and Origin

The scientific community supports the general consensus that the origin of life occurred approximately 3,600 million years ago (Ma). Science accepts that all living beings share the same biochemical organization and the same genetic code.

Foundational Principles of Life and Evolution

• All living beings have a common origin.
• The development of life has been continuous, confirming that evolution is a biological fact, not merely a hypothesis.
• Homo sapiens originated from a primate mammal, from which our species has evolved.

Defining Evolution

Evolution is defined as the process by which individuals of a species undergo qualitative changes that lead to the species transforming from more primitive life forms into more organized ones. This process relies on two fundamental mechanisms:

• Adaptation: Changes that improve an organism's survival conditions in the environment they inhabit.
• Inheritance: Ensures the genetic transmission of these advantageous changes to the descendants.

Historical Evolutionary Theories

Lamarck's Transformational Theory

The first explicit theory of the evolution of species is attributed to Jean-Baptiste Lamarck, who developed the Transformational Theory.

Under this theory, nature is a continuum where species are not invariant but transform, evolving from one form to another, following a trend toward more perfect forms. Lamarck explained evolution by the necessity species have to adapt to their environment. They develop appropriate organs or suffer atrophy (use and disuse), eventually transforming the species.

Darwin's Theory of Natural Selection

Charles Darwin definitively completed evolutionary theory. His main theses are:

1. Common Origin of Species: The variety of known species are related to each other, sharing a common origin.
2. The Struggle for Survival: All species tend to reproduce excessively, potentially saturating their habitat.
3. Theory of Natural Selection: Not all individuals are prepared for this competition. The fittest individuals tend to survive and reproduce.
4. Inheritance: Survivors transmit advantageous genetic changes to their descendants.

Clarification on "Fittest"

The concept of "fittest" is not understood to mean more intelligent, nor does it imply any racist or ethnocentric consideration.

Natural selection is not a conscious process; it acts randomly and blindly. Variations arise spontaneously, meaning the "fittest" outcome cannot be predetermined or proposed by the organism.

The Modern Synthesis

Neither Darwin nor Lamarck could fully explain how the inheritance of characteristics occurs. The New Evolutionary Theory (often called the Modern Synthesis) is a vision of reality defined by three key features:

• Materialistic: Nature is matter, requiring no explanation based on spiritual reality, only scientific principles.
• Dynamic: In nature, everything changes; nothing remains static.
• Progressive: Through evolution, species achieve higher levels of complexity and organization.