Unveiling Paleontology: Fossils, Evolution, and Hominization
Paleontology: Unveiling the Past
Paleontology studies the remains of living beings that lived in the past. Since antiquity, fossil remains of animals have been discovered. To explain their existence, the diluvian theory was used, according to which such remains were those of animals now extinct as a result of “Noah’s Flood.” This scenario could not explain the progressive ratio found from fossils dating in older times to more recent times. Thus, the diluvian theory was replaced by the theory of catastrophes. Under this theory, there would have been many natural catastrophes since the creation of the world, removing ancient species and giving rise to new, more perfect ones each time.
Comparative Anatomy and Embryology
Comparative anatomy allows us to establish the degree of similarity in the organs and their functioning. For example, whales, dogs, and humans share a similar bone structure in their anterior ends. This is only explicable if we assume they all come from the same ancestor from whom they would have inherited these characters.
Embryology studies the embryonic development of living things, showing the similarities in the embryonic development of many different species. This study of embryos has revealed, among other things, that ontogenetic development (the changes individuals undergo to become adults) repeats the phylogenetic development (the changes an evolutionary line undergoes into a particular species).
Genetics and Molecular Clocks
Genetics is the science that studies the mechanisms of transmission of biological characteristics. The variability that exists between individuals of a species is due to two factors:
- The hereditary material that is transmitted to descendants may undergo random changes (mutations).
- Sexual reproduction allows recombination of characters from both parents.
Molecular clocks consist of the observation that the structure of certain molecules common to all living beings is modified at a uniform rate. By studying the rate at which these molecules vary from one species to another, one can calculate the time since both species began to differentiate.
Darwin Versus Synthetic Theory
Key advancements since Darwin’s original theory:
- Genetics has allowed us to discover that spontaneous mutations occur at the time of DNA replication, which are of great importance in the appearance of new species.
- Besides natural selection, there are other mechanisms to explain the appearance of new species, such as genetic drift.
- Evolution is not always gradual and continuous.
- The number of fossil remains found and analyzed in the last decades has allowed us to reconstruct, with enough precision, the evolutionary line that led to some of the existing species.
Hominization: The Rise of Homo Sapiens
Hominization is the evolutionary process that leads to the appearance of Homo sapiens. Distinguishing features of Homo sapiens:
- Walking upright (bipedalism)
- Free hands and grasping ability
- A brain with a high cerebralization index
- Using language for social interaction
- Cultural beings
Hypothesis of fetalization or neoteny: This type of mutation causes adult individuals to sexually maintain their own physical traits of childhood or larva. This phenomenon would occur as a result of a change in regulatory genes, whose function is to activate or inhibit the remaining genes.
The word nature comes from the Latin natura (from the verb nasci, to be born) and has been used historically to translate the Greek physis (which comes from the verb phyein = produce, emerge, grow).