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Questions and Answers
Which factor contributed to the increase in life expectancy during the mid-19th century?
What health issues have increased morbidity in the modern era?
What is one major contributing factor to ecological disruption?
What was a significant health-related change that occurred during the Paleolithic era?
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What statement best reflects the concept of 'One Health'?
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What characterizes a polygenic adaptation?
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What marked the end of the Paleolithic period?
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What is one key characteristic of the last common ancestor between humans and chimpanzees?
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What adaptation is primarily associated with Homo erectus?
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What is a primary reason humans have a mismatch with sedentary lifestyles?
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What is the primary focus of dietary adequacy?
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Which of the following statements about fast-twitch muscle fibers is true?
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Why is the genetic diversity found outside of Africa considered a subset of that within Africa?
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Which nutrient category includes fats and water?
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What is a characteristic of slow-twitch muscle fibers?
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What does the term 'haplogroup' refer to?
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What does the Constrained TEE Hypothesis imply about total energy expenditure?
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Which of the following differentiates morbidity from mortality?
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What was a consequence of the shift towards an agricultural lifestyle?
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Which statement about hunter-gatherer populations is true?
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Which physical adaptation in Homo erectus supports the idea of persistence hunting?
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What is one reason humans evolved to avoid unnecessary energy expenditure?
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Which of the following statements about slow-twitch muscle fibers is true?
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What does the term 'cline' refer to in population genetics?
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How do genetic tests potentially challenge the concept of race as a genetically determined category?
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Which of the following accurately describes the adaptations of humans for thermoregulation?
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What is a characteristic of human muscles consuming approximately 40% of resting metabolic rate (RMR)?
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What defines population substructure in genetic terms?
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Study Notes
The Evolution of Human Health
- Early hominids lived in small, dispersed groups which limited the spread of pathogens.
- Humans and non-human primates share many parasite species.
- The Industrial Revolution in the 19th century led to a decline in infectious disease mortality and an increase in life expectancy. Contributing factors included improved nutrition, pasteurization, public healthcare, and vaccinations.
- The decline in infectious disease mortality was accompanied by an increase in chronic diseases like cancer, diabetes, heart disease, and autoimmune disorders. Contributing factors are air and water pollution, urbanization, processed foods, and sedentary lifestyles.
- The Third Transition of human health is characterized by globalization, ecological disruption, antimicrobial resistance, and factory farming.
One Health
- The "One Health" concept acknowledges that human, livestock, and wildlife health cannot be analyzed in isolation.
- Selective sweeps refer to beneficial mutations increasing in frequency through natural selection in a population.
- In a hard selective sweep model, humans migrating to new environments experience strong selection for novel beneficial mutations.
- Polygenic adaptation involves natural selection favoring multiple alleles in a population, each with a small effect on the adaptive phenotype. This is a faster mode of adaptation and most human genetic adaptations are polygenic.
The Paleolithic Era
- The Paleolithic period began with the use of stone tools by hominins around 3.3 million years ago, ending with the last glacial period approximately 11,650 years ago.
Sedentary Lifestyles as an Evolutionary Mismatch
- The last common ancestor of humans and chimpanzees exhibited many chimpanzee characteristics, including physical activity levels.
- Chimpanzees are twice as strong as humans, walk less than 1.5 miles per day, rarely sprint, have mostly fast-twitch muscle fibers, and struggle to cool efficiently through sweating.
- Homo erectus evolved adaptations for bipedalism, including a larger gluteus maximus, short toes, and head stabilization for running, suggesting persistence hunting.
- Humans evolved for regular, moderate amounts of endurance physical activity. We have more slow-twitch muscle fibers, evolved efficient sweating for thermoregulation, and have large glutes.
- Humans also evolved to avoid unnecessary energy expenditure, as evidenced by a higher percentage of body fat compared to chimps.
- Contemporary hunter-gatherers often maintain energy balance, with periodic scarcity and abundance depending on the season.
- Muscles consume about 40% of resting metabolic rate (RMR) and undergo hypertrophy or degeneration based on usage.
- Many systems, including the circulatory, skeletal, and nervous systems, are activated during physical activity or degenerate under sedentary conditions.
Human Settlements and Domestication
- Human settlements with plant and animal domestication arose 4,000-12,000 years ago in various locations.
Clines and Substructure
- A cline refers to the gradual decrease in frequency of variants (alleles or phenotypes) as one moves away from a geographic region where they are more common.
- Population substructure within a cline refers to the clustering of allele frequencies due to non-random mating.
Genetic Ancestry Tests
- Direct-to-consumer ancestry tests compare a test-taker's haplogroups to the frequency of haplogroups in reference populations.
- Haplogroups are groups of similar haplotypes (DNA sequences) that share a common ancestor.
- Ancestry tests identify the reference populations with a high frequency of the test-taker's haplogroups, providing insight into their ancestral origins.
- The genetic clustering in a reference population depends on the individuals included in the database.
The Constrained TEE Hypothesis
- Total energy expenditure (TEE) can be broken down into components like basal metabolic rate (BMR), physical activity, thermogenesis, immune function, digestion, reproduction, and more.
- The Constrained TEE hypothesis suggests that TEE is limited at high levels of physical activity.
Morbidity vs. Mortality
- Morbidity refers to the rate of a disease in a population.
- Mortality refers to the proportion of deaths in a population.
Health of Hunter-Gatherers
- Hunter-gatherer populations experience low rates of chronic diseases like heart disease, hypertension, diabetes, and cancer.
- Their expected lifespan at birth is around 30-40 years due to high infant mortality from infectious diseases.
- Once reaching age 15, they have an expected lifespan of 72 years.
Critiques of the "Paleo Diet"
- There is no single Paleolithic diet, as macronutrient composition and plant vs. animal-derived foods vary widely across populations.
The Consequences of Agriculture for Human Health
- The shift toward a carbohydrate-based diet following agriculture led to skeletal signs of nutritional deficiencies in the archaeological record.
- Agriculture resulted in dramatic increases in population size, increases in infectious disease, and greater inequality.
- The effects varied due to differences in geography, politics, culture, and population size.
What is a Hominin?
- Hominins are a group that includes humans, our ancestors, and great apes.
- Hominids are a broader grouping encompassing humans, our ancestors, and other great apes like chimpanzees, gorillas, and orangutans.
- Hominoids include all apes, including lesser apes like gibbons and siamangs.
Dietary Adequacy
- Dietary adequacy refers to the extent to which one's food intake meets their nutritional needs.
- It is assessed using a 24-hour dietary recall.
- Six broad categories of nutrients are essential: carbohydrates, protein, fats, vitamins, minerals, and water (macronutrients and micronutrients).
Fast-Twitch vs. Slow-Twitch Muscle Fibers
- Fast-twitch muscle fibers can quickly split ATP (adenosine triphosphate) and rely on anaerobic metabolism. They contract quickly and are good for generating short bursts of strength or speed.
- Slow-twitch muscle fibers are more metabolically efficient and rely on aerobic metabolism. They contract slower but possess greater endurance than fast-twitch fibers.
Human Genetic Diversity
- Most human genetic diversity originated in Africa, where Homo sapiens evolved and persisted for over 100,000 years.
- Genetic diversity outside of Africa is a subset of what exists within the continent due to the founder effect and genetic drift.
Why did hominins evolve bipedalism?
- The answer is complex and the subject of ongoing scientific inquiry.
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Description
Explore the transformation of human health from early hominids to the modern era. This quiz covers critical developments such as the impact of the Industrial Revolution, the rise of chronic diseases, and the concept of One Health that connects human, livestock, and wildlife health. Test your knowledge on how these changes shape our understanding of health today.
