Evidence for Evolution: Fossils, Biochemistry, Anatomy
Evidence for Evolution
Paleontological evidence: Fossils have been found with features intermediate between species and even different taxonomic groups. These fossils have helped reconstruct the evolutionary histories of horses, dinosaurs, molluscs, etc.
Evidence from Comparative Biochemistry: Comparative analysis of different molecules that comprise living organisms has provided data that supports the evolutionary process:
- The essential chemical components of all organisms are the same.
- Identical metabolic processes (chains of chemical reactions) are found in organisms as distant as bacteria and mammals.
- The closer the relationship between two organisms, the more alike the composition of their proteins and DNA.
Evidence from Comparative Anatomy: This field compares the anatomy of animals and the organs of different species. Studies have shown that the structural design of many organs is the same in different organisms, suggesting a common origin. These are called homologous organs.
Adaptation to different environments or circumstances can cause some organs to function differently or become non-functional over generations. These are vestigial or residual organs, which represent the remains of organs that were functional in the ancestors of the present species.
Evidence from Domestication: The current characteristics of cows, pigs, or dogs are the result of selection carried out over centuries by humans through domestication and cultivation. This demonstrates how gradual changes can occur through selective breeding and artificial selection.
Evidence from Geographical Distribution: When analyzing the distribution of extant species on the planet, it’s clear they are not distributed evenly across all continents. This can be explained by considering the evolutionary need for colonization, but geographical barriers (oceans, seas, mountains) or other factors can prevent it. Moreover, the isolation characteristic of islands causes species to change over time (evolve) and give rise to unique flora and fauna (endemic species), descended from colonizing ancestors.
Evidence from Embryology: Similarities in the early stages of embryonic development clearly show features that correspond to the characteristics of their “inferior” ancestors, which disappear as development is completed.
Evidence from Systematics: Classifications can be represented as family trees that illustrate the relationships between organisms and their common ancestors. This involves measuring biochemical, anatomical, and paleontological data, resulting in modern phylogenetic classifications that show the evolutionary relationships between organisms or groups of related organisms.
Analysis of Lamarck’s Proposal:
- Lamarck failed to demonstrate any trend or impulse towards complexity in any creature.
- He could not prove the inheritance of acquired characteristics. Genes, not acquired features, are inherited. Furthermore, the genes that are transmitted (genotype) are localized in specialized cells, gametes, which are not influenced by the development or atrophy of organs, which, according to Lamarck, are influenced by the environment.