Evolutionary Biology Quiz

Diversity of Life

• Earth is home to approximately 8.7 million species.
• Explaining this vast biodiversity with a unified theory has been challenging.
• Debates continue, with some theories challenging natural selection.

Mechanisms of Evolution

• Five fundamental mechanisms drive biological evolution:
  • Natural selection
  • Sexual selection
  • Genetic drift
  • Gene flow
  • Mutation

Observations Before Darwin & Wallace

• Change occurs over time.
• Traits have a purpose.

Darwin & Wallace's Explanatory Challenge

• Understanding why changes occur.
• Explaining how new species arise.
• Defining the function of traits.

The Origin of Species (Darwin 1859)

• Natural selection hinges on three pillars:
  • Competition:
    • Unlimited resources lead to exponential population growth, resulting in a struggle for existence.
  • Variation:
    • Individuals differ in their competitive abilities.
    • Advantageous variations lead to selection.
    • Individuals best adapted to their environment are more likely to survive.
  • Heritability:
    • Variations are inheritable.
    • Differential reproductive success drives the evolution of particular populations.

Natural Selection Scrutinized

• Populations generally exhibit exponential growth.
• Sufficient time has elapsed for evolution to occur.
• Variation is indeed heritable.
• Some traits, like sexual dimorphism, appear to have no survival benefit; their function likely lies in mating/reproductive advantage

Genes

• Genes dictate physical appearance and bodily functions.
• They contain instructions for protein production.
• Proteins are essential for bodily structure and various life processes.
• Genes reside on strands of DNA (deoxyribonucleic acid).
• Gregor Mendel (1865): Organisms possess two versions of each gene (alleles), one from each parent.
• DNA replicates and transmits to offspring.
• Genotype (genetic makeup) vs. phenotype (observable traits)
• Genetic variation arises from:
  • Sexual reproduction
  • Mutation
  • Genetic drift
  • Gene flow

The Selfish Gene

• Genes are the units of selection in biological evolution, not individuals or traits.
• Genes are inherently self-interested.
• Biological fitness is measured by the number of gene copies passed on.

Sexual Selection

• Intersexual selection:
  • Preferential mate choice, often driven by female choice and gametic investment.
• Intrasexual selection:
  • Competition among members of the same sex for access to mates (e.g., status, combat, resource control).

Evolution of the Human Species

• Homo sapiens span 200,000 years.
• Cognitive revolution (70,000 years ago).
• Industrial revolution (200 years ago).
• Digital revolution (20 years ago).
• Hunter-gatherer societies (small, family-based groups; likely egalitarian).
• Division of labor. High child mortality, but potentially long lifespan.

Evolution and Human Behavior

• Evolution and psychology are intertwined.
• Genes influence cognition, behavior, learning, and culture.
• Physical and behavioral traits are gene-dependent; the forces shaping the body also shape the mind.

Evolutionary Psychology (EP)

• EP aims to understand the mind's design through natural selection.
• Not a specific area of study, rather, it's a method applicable to many areas.
• The mind is specialized for information processing.
• Its design reflects adaptations to ancestral hunter-gatherer environments.

Five Principles of Evolutionary Psychology

• 1. Physical System: The brain operates under physical laws
• 2. Natural Selection's Design: Neural circuits evolved to solve ancestral problems.
• 3. Hidden Mental Processes: Much mental activity is unconscious.
• 4. Specialized Circuits: Circuits for specific adaptive needs.
• 5. Stone Age Minds: Our minds are products of our evolutionary history.

Environment of Evolutionary Adaptedness (EEA)

• Modern environments often mismatch the adaptive solutions forged in the EEA.
• Mismatch example 1 (fear): Fears of ancestral threats (e.g., snakes, spiders) are more common than modern ones.
• Mismatch example 2 (diet): Modern diet mismatches the EEA; cravings for energy-dense foods are maladaptive in a world of abundant, processed food.

Evolutionary Psychology Example: Aggression

• Aggression as a context-sensitive solution to various adaptive problems (resource acquisition, intrasexual competition, mate defense, etc.).
• Seven evolutionary arguments for aggression.

Criticism of Evolutionary Psychology

• Challenges to Methodology: Difficulties in testing backwards inferences and reliance on "just so stories."
• Ambiguity about EEA pressures.
• Gender bias, potential for misinterpretations, non-adaptive explanations, and more.

Comparative Evolutionary Psychology

• It addresses the limitations of EP's dependence on EEA speculation by focusing on evolutionary theory in comparisons.
• It uses comparisons with other species and development studies.
• It combines perspectives from developmental psychology, phylogeny, and cross-cultural studies.
• Unveiling the relationship between universal behaviors and behavioral variation.

Intersexual and Intrasexual Selection

• Natural selection prioritizes survival, while sexual selection focuses on mating success.
• Intrasexual selection: Competition between same-sex individuals for access to the opposite sex.
• Intersexual selection: Mate choice based on preferences for specific attributes.

Parasite Theory

• Parasites are a significant mortality factor.
• Sexual selection pressures: attractiveness as a signal of strong immune system.

Averageness Hypothesis

• Composite/average faces are generally perceived as more attractive than non-average faces.

Parental Investment Theory (Trivers 1972)

• Parental investment is any investment increasing offspring survival that comes at a cost to the parent's investment in other offspring.
• Mating and rearing investments.
• Relative gamete size (eggs larger than sperm).
• The sex investing more in offspring is often more selective.
• The sex investing less often competes for mates.

Mate Preferences

• Significant sex differences in mate preferences observed across a wide range of cultures and societies.
• Males often prioritize fertility, while females prioritize resources.

Problems With EP Approach

• Intra-cultural variation.
• Biased samples.
• Socially desirable responses.
• Contributions from other disciplines (e.g., social psychology).

Mate Preferences: Facial and Odor Preferences

• Masculinity preferences.
• MHC (major histocompatibility complex) compatibility preference, particularly in ovulating women.

Social Roles & Evolutionary/Social Psychology

• Evolutionary vs. social psychology arguments for mate preferences.
• Social structure as an influential determinant.
• Gender equality and its effect on mate preference differences.

Test your knowledge on the principles of evolution, the mechanisms driving biological change, and the contributions of Darwin and Wallace. This quiz covers important concepts related to the diversity of life and the challenges of explaining evolution.