Evolutionary Evidence: Fossils to DNA Analysis
Paleontological Evidence
- Fossils: Mineralized remains of organisms found in sedimentary rocks. They reveal past life forms and their evolutionary relationships to current species.
- Some fossils, like *Archaeopteryx* (a primitive bird with feathers and teeth), represent intermediate forms between major groups, linking birds and reptiles.
- Modern geological dating techniques determine the age of fossils.
Embryological Evidence
Embryology, the study of early organism development, reveals that embryos of different vertebrate classes are remarkably similar in their early stages, gradually differentiating over time.
This observation led German scientist Ernst Haeckel to propose the principle of recapitulation, suggesting that an animal’s embryonic development summarizes its species’ evolutionary development.
Taxonomic Evidence
The classification system of living beings, initially based on fixed categories, groups organisms with similar characteristics. These similarities, resulting from a shared evolutionary process (like embryonic development), serve as further evidence of evolution.
Recent Evidence
Modern fields like biochemistry and molecular genetics provide additional evidence.
Comparative Biochemistry and Cell Biology
Demonstrates a chemical unity among living organisms, indicating common ancestry:
- The Genetic Code: The relationship between nucleic acid and protein sequences is universal, with only minor variations.
- ATP: This molecule provides energy for cellular metabolism.
- Metabolic and Physiological Processes: Key processes like cellular respiration and photosynthesis are common to vastly different organisms.
Sequences of Proteins and DNA
Comparing nucleotide sequences of the same gene or amino acid sequences of the same protein from different species reveals similarities. Higher similarity indicates closer evolutionary proximity, allowing the construction of phylogenetic trees.
DNA Hybridization
DNA can be denatured and then renatured, re-establishing hydrogen bonds between its base pairs. Incubating DNA from two different species allows hybridization in areas with complementary sequences. More numerous complementary sequences indicate a higher degree of relatedness between species.
Study of Chromosomal Banding
Evolutionary cytogenetics studies and compares the chromosomal shapes and characteristics of each species. Chromosomal banding allows for longitudinal differentiation and characterization of each pair of homologous chromosomes. This helps establish chromosomal homologies between different species.
Immunological or Serological Analysis
Introducing an antigen into an organism triggers antibody production, resulting in agglutination. The intensity of agglutination reflects the evolutionary relationships between species.