Evolution 3

Evolution and Human Biology

• Presenter: Fiona O'Shea, School of Human Sciences, University of Western Australia

Learning Objectives

• Demonstrate understanding of evolutionary principles and processes.

• Utilize evolutionary theory to explain the modern human condition and the challenges we face.

Evolutionary Change

• Caused by differential survival and reproduction.

  • Variation: Differences among individuals in a population.

  • Differential Reproduction: Some individuals with advantageous traits reproduce more successfully.

  • Selection: Environmental pressures influence which individuals survive.

  • Heredity: Traits are passed on to offspring.

Evolutionary Pressures

• Biotic Factors:

  • Competition: Struggle for resources among individuals.

  • Predation: Impact of predators on survival.

  • Disease: Influence of parasites and pathogens.

• Abiotic Factors:

  • Climate: Effects of temperature, precipitation, etc.

  • Topography: Influence of physical geography on living conditions.

  • Habitat: Type of environment organisms live in.

• Overall Process:

  • Acts on phenotype across all life stages and can influence populations across many generations.

  • Result: Genetic change in a population over generations.

Natural Selection in Human Populations

• Genetic adaptations to environmental changes:

  • High Altitudes: Adaptations in Tibetan and Andean populations.

  • Arsenic Tolerance: Observed in Puna Indians of the Argentinian Andes.

  • Lactose Tolerance: Emergence in agricultural communities.

Environmental Influences on Body Structure

• Cold Environments:

  • Larger body weight and shorter limbs enhance heat retention.

• Warm Environments:

  • Smaller body weight and longer limbs enhance heat dissipation.

Ongoing Evolution

• Urban dwellers likely possess DNA variants granting resistance to infections.

  • Increased resistance to diseases such as TB and leprosy observed in urban populations.

  • Regions in Africa exhibit resistance to HIV.

• Environmental modifications have relaxed selection pressures:

  • Availability of clean water and healthcare services.

  • Increased reliability of food supply.

Relevance of Evolution to Human Biology

Medicine

• Evolutionary Medicine: A field applying evolutionary theory to health and disease.

  • Understanding the rapid evolution of emerging diseases (e.g., H1N1, SARS, COVID-19).

  • Investigating disease origins helps shape research (e.g., HIV related to SIV).

Treatment of Disease

• Challenges like antibiotic resistance impacting treatment effectiveness.

• Implications for vaccine development and drug formulation:

  • Use of drug cocktails and alternative sourcing due to resistance concerns.

Disease Vectors

• Transmission modes impact disease effects:

  • Malaria (vector-borne), waterborne diseases (cholera, dysentery), airborne diseases (common cold).

Historical Gene Impact

• Historical gene advantages can be detrimental today:

  • Hereditary conditions like hemochromatosis influenced by high iron diets.

  • Thrifty gene linked to obesity and metabolic syndrome.

Evolutionary Trade-offs

• Skin Pigmentation:

  • Balancing UV protection and vitamin D synthesis effectiveness.

• Female Pelvis:

  • Compromise between bipedal locomotion and the birthing process (obstetric dilemma).

Applications in Forensics

• Utilizing evolutionary principles in DNA analysis:

  • Assessing matches between crime scene samples and population profiles.

Applications in Agriculture & Horticulture

• Application of evolutionary concepts to enhance crop yields and livestock.

  • Practices involve selective breeding known as "applied evolution."

Influence on Human Behavior

• Evolutionary heritage reflected in human behavior:

  • Emotional responses, familial relationships, parental care, mate selection, and long-term partnerships.

Evolution Essentials

• Core components of evolution include:

  • Reproductive systems, inherited variations, changing environments, selective pressures, and varying reproductive successes (fitness).

Evolutionary Mysteries

• Ongoing questions and areas for research in the field of evolution.

Notable Quote

• "Nothing in biology makes sense except in the light of evolution" - Theodore Dobzhansky.