Biology and Anthropology: Understanding Human Evolution
All individuals are the result of the interaction between biology and anthropology.
Cultural Anthropology: Nature vs. Nurture
Cultural anthropology distinguishes between natural behavior (genetically transmitted information) and cultural behavior (information acquired by social learning). Biology distinguishes between genotype (a combination of genes on chromosomes; innate) and phenotype (interaction of genotype with the environment; acquired throughout life).
Nature vs. Culture
- Nature: Innate, something you’re born with because it is genetically preprogrammed or develops in the embryonic and fetal stages.
- Culture: Acquired by social learning from birth.
Origin of Species: A Common Ancestry
The scientific community generally accepts that life expanded from a single root, like the branches of a tree. All living things share a common origin. The development of life has been continuous and seamless, so evolution is considered a biological fact, not a mere hypothesis. Homo sapiens originated from a primate mammal from which our species evolved.
Developments: Adaptation and Heredity
Developments are the process by which individuals of the same species undergo qualitative changes that lead to species change from more primitive life forms to more organized ones. There are two key mechanisms:
- Adaptation: Undergoing changes to improve survival conditions.
- Heredity: Genetics ensures the transmission of these changes to descendants.
Fixity of Species: Historical Perspectives
Fixity According to Species
The concept of fixity suggests that species are:
- Fixed (unchanged since their origin).
- Isolated groups (not derived from or related to each other).
- Created by God (appearing at a unique moment through divine work).
- Immutable (each individual and species remains unchanged since creation).
Fixism According to Philosophers
Fixity implies a hierarchical conception of reality, where each individual has a proper place within nature. Human nature is fixed and immutable (within a range of individuals who are born, grow, and die). The human being is the subject of creation and distinct from animals.
Evolutionary Theories: Lamarck and Darwin
Lamarck: Transformation of Species
Lamarck proposed that nature is a continuum, and species transform from one to another, trending towards greater perfection.
Darwin: Natural Selection
- Common Origin of Species: Most known species are related, originating from one or a few primitive species.
- The Struggle for Survival: All species tend to breed to saturate their habitat.
- Concept of the Fittest: Not necessarily smarter or stronger, but best suited to the environment.
- Random Performance: Natural selection is not a conscious process; nature acts randomly and blindly.
- Heredity: Survivors transmit advantageous genetic changes to their descendants, expanding the species’ capabilities.
- Theory of Natural Selection: Only the fittest individuals survive the competition.
Evolution as a Fact: Materials, Dynamics, and Progression
- Materials: Through evolution, species achieve a higher level of complexity and organization.
- Dynamics: Everything in nature changes, but so slowly that we cannot perceive it.
- Progressive: Nature is self-governed, explained by science rather than spiritual reality.
Process of Human Evolution: Hominization and Humanization
- Hominization: The process of evolutionary biological changes that characterize the evolution of hominids, leading to the modern human species.
- Humanization: The psychosocial change process, giving rise to cultural elements that characterize and distinguish humans from other species.
Hominization Process Changes: Bipedalism and Brain Capacity
- Bipedalism: A fundamental change from walking on all fours to walking on two legs. This shifted the center of gravity to the pelvis, narrowing it and modifying the vertebral column. This led to the liberation of the hands for tool use and manipulation.
- Increased Brain Capacity: As hands became free, brain size increased. The need to attack with the mouth diminished, altering the jaws and skull size.
Humanization: Social Behavior and Language
These changes were possible because the primate species from which we evolved were not limited by fixed, instinctive behavior. They had the ability to learn new techniques and modes of existence, including:
- The emergence of social behavior.
- The emergence of language.
- Long apprenticeship periods.
- Hunting.
- The discovery of fire.
Stages in Human Evolution
Key stages in human evolution include:
- Homo sapiens sapiens
- Homo sapiens neanderthalensis
- Homo erectus
- Homo habilis