Evolutionary Evidence & Theories: Understanding Life’s History
Modern Hypotheses on Life’s Origin
One of the possible locations where living organisms could have originated are deep-sea hydrothermal vents. According to some scientists, these places release inorganic matter, which, along with water and carbon dioxide, formed the first complex molecules. The energy needed for this process could have come from the oxidation of reducing agents.
According to this hypothesis, two possible mechanisms could have led to the formation of the first cell:
- Self-replication
- Metabolism
Compelling Evidence for Evolution
Anatomical and Morphological Evidence
Organs can be classified into three groups that support the theory of evolution:
- Homologous organs: Organs that may perform different functions but share the same evolutionary origin, providing evidence of divergent evolution.
- Analogous organs: Organs that perform the same function despite having different evolutionary origins, providing evidence of convergent evolution.
- Vestigial organs: Organs that tend to disappear because they are no longer useful, providing evidence of habitat change.
Embryological Evidence
In 1866, Ernst Haeckel proposed his biogenetic law, stating that embryonic development recapitulates evolution. Similarities among embryos of different species indicate an evolutionary relationship. The closer the species, the greater the similarities.
Biogeographical Evidence
The geographical distribution of animal and plant species can be explained by evolutionary theories. Over time, isolated groups of animals evolved in different ways, leading to the creation of new species.
Molecular Evidence
The study of molecules in living organisms reveals that greater molecular similarities between two organisms indicate a closer evolutionary relationship. By comparing the amino acid sequences of different species, we can accurately establish their evolutionary relatedness.
Additional Evolutionary Evidence
- Coevolution: The process by which two species mutually influence each other’s evolution.
- Mutualism: An interaction between two species where both benefit.
- Parasitism: When one species benefits at the expense of another.
- Mimicry: The capacity of some species to resemble other species or their environment to ensure survival.
- Domestication of species demonstrates that artificial selection has profound effects on domesticated animals.
- The stratum in which a fossil is found indicates its age.
Lamarck’s Theory of Acquired Traits
Jean-Baptiste Lamarck was the first to propose a logical theory of evolution, known as the theory of inheritance of acquired traits. It posited that animals develop structures and organs they need to adapt to their environment, and these new characteristics are then transmitted to offspring, leading to species change over time.
Although not accepted today, Lamarckism introduced several important ideas:
- Recognized the relationship between anatomical structures and their purpose.
- Explained that organisms adapt to their environment.
- Acknowledged an evolutionary process and proposed a mechanism to explain it.
However, its key flaws included:
- Claimed that acquired characteristics are transmitted to offspring.
- Claimed animals had an internal need to improve themselves.