Lamarck's Theory: Anthropology Notes

• Notes on Anthropology topics

Jean-Baptiste Lamarck's Theory

• Lamarck was a naturalist who studied biological evolution and was an early member of the French Academy of Sciences
• He researched animals and plants, working in botany and zoology

Main Tenets of Lamarck's Theory

• Law of Use and Disuse
• Inheritance of Acquired Characteristics
• Tendency toward Perfectionism

Law of Use and Disuse

• Lamarck believed that organism organs develop or atrophy based on their use (e.g., giraffe's neck)

Inheritance of Acquired Characteristics

• Lamarck posited that characteristics acquired during an organism's lifetime could be inherited by its offspring

Tendency Toward Perfectionism

• Lamarck thought species have a natural drive towards complexity and perfection

Classic Examples of Lamarck's Theory

• Giraffe Example: Ancestors of giraffes stretched their necks to reach high leaves, leading to an inherited elongation
• Crab Example: If a crab loses a claw through disuse, its descendants would be born with smaller or no claws

Criticisms and Limitations of Lamarck's Theory

• The inheritance of acquired characteristics has been disproven by genetics

Contributions of Lamarck

• He was the first to propose a theory about evolution
• Lamarck introduced the idea that organisms change over time
• He laid the groundwork for Darwin and others to develop more precise theories

Natural Selection

• Natural Selection is a core concept in evolutionary biology where populations of organisms change over time due to genetic variation and adaptation to the environment
• In anthropology, it is applied to the study of human evolution and the genetic diversity of human populations

Objectives of Natural Selection

• Maximize Survival: Individuals more adapted to their environment are more likely to survive and reproduce
• Maximize Reproduction: Individuals who survive and reproduce successfully pass on their genes, increasing the prevalence of adapted traits

Natural Selection Hypothesis

• Drawing from Darwin's work, organisms with favorable traits in a given environment are more likely to survive and reproduce

Methodology of Natural Selection

• Observation and Monitoring: Observing populations of organisms in their natural environment to study natural selection
• Experimentation: Conducting experiments in controlled lab or field settings to study natural selection
• Genetic Analysis: Analyzing genetic variation within populations to study natural selection at the molecular level

Results of Natural Selection

• Adaptation
• Evolution
• Genetic Diversity
• Speciation
• Extinction

Conclusions About Natural Selection

• It explains how species evolve and adapt to their environments over time
• Characteristics that aid survival and reproduction are passed on to future generations, leading to biological diversity
• This mechanism is key to understanding evolution in nature and adaptation to environments

Migration

• Migration is an evolutionary mechanism referring to the movement of individuals from one population to another, creating genetic flow between populations
• Migration is also known as gene flow in evolutionary biology

Important Points About Migration

• Introduces specific alleles into new populations
• Can homogenize populations of the same species
• Can cause different effects among arrival populations, depending on exchanged alleles

Migration Research

• Genetic variability has been modeled by gene flow
• Scientists reconstructed Neanderthal genomes through DNA sequencing
• Some Neanderthal sequences are found in modern humans

Migration Results

• Introduces new variability by hybridization between ancient humans and Neanderthals
• Affecting immunity, metabolism, and influencing risk for diabetes, also modifying skin tone

Migration Conclusion

• Alters allelic frequencies in a population due to adding a new individual
• Changes both phenotype and genotype through gene exchange

The First Living Things

• Early life originated in the sea as unicellular organisms
• Later, organisms capable of photosynthesis evolved, followed by complex life forms

Prokaryotic Cells

• The first living things were prokaryotic cells, similar to bacteria, which inhabited Earth around 3.5 billion years ago

Unicellular Living Things

• Early life forms were unicellular and aquatic organisms
• They were anaerobic and fed on organic compounds in the water

Primordial Soup Theory

• Early life forms originated from bodies of primitive water containing complex organic matter
• This organic matter formed from inorganic substances present in Earth's reducing atmosphere

Photosynthesis

• Some organisms developed the ability to perform photosynthesis
• It allowed them to obtain energy from sunlight and release oxygen into the atmosphere, leading to the emergence of aerobic organisms

Pluricellular Living Things

• The first pluricellular organisms appeared about 610 million years ago
• The first animals appeared and were like arthropods, such as centipedes and scorpions

LUCA

• All living things are believed to descend from a single organism: LUCA (Last Ultimate Common Ancestor)
• LUCA lived in geothermal pools that could exceed 90°C

Appearance of Fungi and Insects

• Plants and fungi appeared around 500 million years ago, followed by arthropods (insects and arachnids)

Complex Living Things

• Amphibians came about 300 million years ago, followed by mammals 200 million years ago, and birds 100 million years ago

First Flowers

• The first flowers on Earth appeared around 120 million years ago, during the Cretaceous period
• Fossils of older flowering plants have been found

Appearance of Humankind

• The appearance of humans on Earth occurred through an evolutionary process that began millions of years ago in Africa
• Primates evolved in Africa 30-55 million years ago

Conclusion on First Living Things

• Through the evolution of living things, organisms adapted over millions of years
• Terrestrial conditions allowed for transformation from unicellular to complex organisms

Genetic Drift

• It is an evolutionary mechanism involving random allele frequency changes in a population over time
• It is unlike the selection natural

Genetic Drift Differs from Natural Selection

• That it occurs randomly and impacts population evolution, especially in small populations

Genetic Drift Example: Island Populations

• It often experience genetic drift due to small size and isolation, leading to unique traits absent on continents

Genetic Drift Consequences

• Loss of Genetic Variation: Genetic drift can reduce genetic diversity, increasing vulnerability to diseases and environmental changes

Genetic Drift Importance

• It is a fundamental component of evolution theory and explains population changes along with natural selection, mutation, and migration

Genetic Drift Conclusion

• Important for understanding evolutionary biology, biodiversity conservation, and endangered species management

Genetic Mutations

• A gene is a section of DNA, the genetic code
• Our genetic code is a template used to create different structures
• DNA determines how our bodies are built and function, like LEGO blocks

Genetic Mutation Definition

• A genetic mutation is a change in our DNA code (nucleotide sequence) involving the four nucleotides: Adenine, Cytosine, Guanine, Thymine
• Errors during DNA copying lead to mutations, Each codon corresponds to groups of three bases and indicates a specific instruction

Genetic Mutation Impacts

• If the bases are altered, modified the way in which information is interpreted
• Substitutions: When one base is changed for another
• Deletions: When one or more bases are removed
• Insertions: When one or more bases are added

Genetic Mutation Classifications

• Molecular Mutations: (genetics or point mutations) - Occurs in the sequence of DNA and its constituent nucleotide bases
• Chromosome Mutations: Alters a chromosome segment, potentially losing, duplicating, or re-arranging genetic information
• Genomic Mutations: Affects an entire set of chromosomes, causing excesses or deficiencies and altering substantial portions of the organism's genome

Types of Mutations

• Morphological Mutations: Involve changes to the body’s form or appearance, affecting coloration, shape, structure, etc
• Lethal and Deleterious: Interrupt processes critical for the organism’s maintenance, leading to death or impaired growth/reproduction
• Conditional: Influence an individual's performance within its biological community, potentially leading to permissive/restrictive conditions regarding viability
• Biochemical/Nutritional: Impact the production of biochemical compounds required for specific functions, like enzymes/metabolites
• Loss of Function: Inhibit the proper function of a gene, causing the organism to lose specific capabilities; unipolar depression in humans caused by mutations in the genehTPH2

Causes of DNA Mutations

• Errors in DNA replication during cell division
• Exposure to mutagens: radioactive substances, X-rays, UV radiation, chemicals
• Viral infections
• Other infectious agents

Genetic Disorders

• Polydactyly is a genetic alteration during fetal development leading to extra fingers on hands or feet
• Marfan Syndrome is caused by defects in a fibrillin-1 gene, altering connective tissue formation
• HIV Resistance results from a mutation in CCR5 gene, preventing retrovirus entry into cells

Mutation Conclusions

• Mutations aren't always harmful since phenotypic changes may improve/degrade an individual's survival capacity depending on environmental conditions
• Most mutations in living organisms are recessive so they may not manifest openly but can be passed on through generations, expressing eventually under certain conditions

Spencer’s Theory

• British philosopher and sociologist, advocated for evolutionary theory in the 19th century
• More renowned for applying evolution theory to society, philosophy and psychology, coining it Synthetic Philosophy
• Considered the father of socioeconomic evolution renowned for the survival-of-the-fittest theory and evolutionary approach

Theory of Evolution (Spencer)

• Societies evolve similarly to animal species through natural selection: fittest societies survive while the less-fit fail
• Spencer advocated limiting government intervention as social evolution is natural

Survival of the Fittest

• Species survive or go extinct in response to adaptation
• Free competition ensures the survival of the fittest in societies

Interdependence

• Individuals and society affect one another so that society evolves through natural selection
• The most viable thrive and the rest don't make it

Darwin's Evolution

• The individuals rights are more important than those of the population
• Government ought to secure freedom and growth

Darwin and the Theory of Evolution

• Charles Darwin was a naturalist and influential scientist and known for his biological evolution theory through natural selection modern evolutionary synthesis
• Species change over time and are from an original species, sharing an ancestor, hereditary differences accumulate creating lots of species

Darwin defined evolution

• Darwin defined evolution as "descent with modification," which means that species change over time, giving rise to new species that share a common ancestor
• The most adapted usually survive

Darwin's Argument

• Only better adapted survive to reproduce, transmitting features to descendant generations, will be more prevalent

Impacts of Darwin

• Scientific Revolution: altering perspectives on life and evolution, and biology
• Modern Biology Development: laying the groundwork for genetics, ecology, and evolution
• Practical Applications: having practical applications in medicine, agriculture, and biodiversity conservation

Mechanisms of Natural Selection

• Directional Selection operates distinctly, favoring creatures that are better suited to the surroundings
• Stabilizing Selection works to maintain population stability by weeding out individual genomes with extreme features
• Disruptive Selection allows increased variety, benefiting any specific trait of the beings

Vitalistic Conclusions

• The science visionary, Charles Darwin, revolutionized life and evolution
• Natural selection, his theory continues and forms the basis for biology, still inspiring philosophers, scientists and other thinkers

Vitalism

• Throughout the past, scientists and philosophers have explained life's functions, leading to two schools: materialism and vitalism
• Mechanism shows life by physical laws however essentialism asserts being carry special energy beyond material ways

Mechanism

• Philosophy and scientific ideas explaining processes of life physically and chemically
• Life acts as an advanced machine: functions are deterministic and predictable

Characteristics of Mechanism

• Laws relate
• Life is described mechanically
• There are no confusing ways
• Based on Descarte's thinking, where the human body is comparable to a machine
• The heart beat is due to contractions and electrical impulses that occur without some "vital" energy

Vitalism

• Life processes require a vitalistic explanation that is something in addition to chemistry
• It is something like the soul

Characteristics of Vitalism

• An energy exists
• Life is not mechanical
• Scholars were supporting
• The vitalistic movement

Vitalism Examples

• In vitalism the process, regenerating in salamanders, expresses intelligent regeneration that provides specific strength
• Mechanism and vitalism continue even though science is mainly mechanical still

Vitalism Conclusions

• Though it has declined, it remains relevant, philosophical in biology's roots
• It is philosophical and important when studying consciousness, health, and life's origin