Evidence of Evolution: Key Biological Mechanisms and Theories

Evidence of Evolution

Paleontology

Fossils have been found with features intermediate between species and even different taxonomic groups.

Comparative Biochemistry

Comparative analysis of molecules that make up living things supports the evolutionary process:

• Essential chemical components of all organisms are the same.
• Metabolic processes are identical.
• The closer the relationship between two species, the more similar their protein chains and DNA composition.

Comparative Anatomy

This branch of biology examines the anatomy of animals and compares the organs of different species.

Domestication

The current features of wheat, cows, dogs, or pigs are the result of selection over centuries by humans.

Geographical Distribution

Analyzing the distribution of existing species on the planet reveals how they are spread across all continents.

Embryology

Similarities in the early stages of embryonic development among major vertebrate groups are striking. These stages show features corresponding to ancestors that disappear as development completes.

Systematics

By considering the relationships of organisms with their common ancestors, it is possible to construct classifications represented as genealogical trees, which are diagrams of evolutionary relationships.

Evolutionary Theories

Mutation

A random change in DNA occurring by chance. In many cases, these are unfavorable and lead to features eliminated by natural selection.

The Synthetic Theory

Variations are due to random mutations. Natural selection chooses favorable mutations, increasing their frequency to lead to adaptation. This process is gradual and slow. Through speciation, population differences accumulate until a new species diverges.

Mutationism

A theory suggesting mutations were the only driver of change and the origin of species, where the transition between species occurred via an abrupt jump.

Neutrality

This theory posits that most mutations are neutral; these random changes favor the survival of certain genes in populations.

Neo-Lamarckism

Suggests that the source of change is not random, but rather mutations determined by the environment.

Punctuated Equilibrium

A theory with many modern supporters that distinguishes between microevolution and macroevolution. It suggests the sudden appearance of new species in the fossil record is due to genetic revolutions.