Evolutionary Biology and the Origins of Humanity
Key Biological Concepts
a. Biodiversity: Refers to the set of species of living things, including plants, animals, and microorganisms.
b. Adaptation: The capacity of an organism to live and thrive in an environment and resist the changes occurring within it.
c. Species: A group of individuals with similar characteristics that can crossbreed, giving rise to fertile offspring.
d. Speciation: The biological process by which new species originate.
e. Anagenesis: The process of change a single species undergoes over time, which makes it different from the ancestral species.
f. Cladogenesis: The process of species diversification into two or more species.
g. Karyotype: The chromosomal endowment of a cell or organism, characterized by the number, size, and configuration of chromosomes.
h. Habitat: The living area or place where a species resides under well-defined environmental conditions.
Characteristics of Class Osteichthyes
Commonly known as bony fishes, their features include:
- Skeletal diagram-habitat: Aquatic.
- Presence of scales.
- Branchial respiration.
- Examples: Grouper, mackerel, trout, and swordfish.
Characteristics of Amphibians
- Internal and external fertilization.
- Oviparous.
- Habitat: Aquatic and terrestrial.
- Heart with three chambers: two atria and one ventricle.
Characteristics of Reptiles
- Internal fertilization.
- Conical teeth.
- Lung breathing.
- Carnivorous diet.
Characteristics of Mammals
Mammals possess mammary glands and hair. Their circulatory system is formed by one heart with four cavities.
Characteristics of Primates
- Opposable thumbs.
- Flat nails.
- Four incisors.
- Frontal eyes.
Evolution of Primates
The ancestor was a mammal similar to a shrew. Primate evolution began when a group of these small insectivores occupied the trees. The adaptation to arboreal life profoundly influenced the evolution of primate hands, pre-adapting them to hold instruments.
Evolution of Mammals
Mammals were the first to evolve from a group of primitive reptiles approximately 200 million years ago. The first mammals of the Jurassic period came from reptiles and were about the size of a rat.
Characteristics of Hominids
- Vertical forehead.
- Erect position.
- Semi-articulated language.
- Bipedalism (walking on two legs).
Factors in Human Evolution
Anatomical Factors
The vertical position of the human body replaces the function of the hands in support and locomotion, leaving them free to take or seize objects and make instruments. The dentition evolved rapidly.
Psychological Factors
The creation of tools, crafts, and social structures, revealed by the use of fire and brain development, demonstrates the first progressive evolution.
Conclusions on the Origin of Man
- The development of the human branch occurred parallel to the ape branch. The hominid branch, which gave origin to man, detached from lemur-like ancestors during the Miocene.
- Evolution is a gradual process.