Human Adaptations to Environmental Stressors and Health

Darker skin populations

Populations near the equator have higher eumelanin levels as a protective adaptation against UV radiation.

Chronic Mountain Sickness

A condition where individuals adapted to high elevations lose their adaptations and experience health issues.

Microbiota

The ecological community of microorganisms living in and on multicellular organisms, important for immune and metabolic functions.

Typology

A method for reducing a spectrum of variation into a smaller set of idealized categories.

Race as a Social Construct

Race is a culturally and socially constructed category that groups people based on perceived biological markers.

Subcutaneous vs. Visceral Fat

Subcutaneous fat is less inflammatory, while visceral fat is linked to higher inflammation and poorer metabolic health.

Critiques of Race

1) Human genetic variation is kleinal, 2) Most traits are discordant, and 3) Genetic variation is widely shared across species.

Hypoxia

A condition of low oxygen levels, often encountered at high altitudes, affecting physiological responses.

Ethnocentrism

The tendency to view one's own culture as superior and to judge the behavior and beliefs of culturally different people by one's own standards.

Polygenism

The belief that different human races are separate species that descended from biologically distinct origins.

Embodiment

The process of biologically incorporating social and material experiences throughout an individual's life.

Biological Adaptation

Changes in physiology or morphology that improve evolutionary fitness in response to environmental changes.

Genetic Determinism

The idea that genes alone determine physical appearance and identity, ignoring environmental and epigenetic factors.

Intergenerational Inheritance Model

A model focusing on how prenatal and infant exposure to environmental conditions affects adult health risks.

Epidemiological Transition

The shift from infectious diseases to non-infectious chronic diseases as the primary cause of mortality in societies.

Eugenics Movement

A movement aimed at improving the human species through planned racial purity and selective breeding.

Genetic Ancestry Tests

Tests that attempt to determine ancestral origins but do not encapsulate the entirety of an individual's identity.

Social Determinants of Health

Factors such as economic stability and education that influence health outcomes in populations.

Hygiene Hypothesis

The theory that lack of early exposure to infections can lead to inappropriate immune responses and autoimmune diseases.

Time Scales of Adaptation Model

A framework examining how the duration of exposure to environmental changes affects biological responses.

Bergman's Rule

Larger animals are found in colder environments to facilitate heat retention.

Kleinal Distribution

The pattern where certain traits have a close predictive relationship with geography.

HPA Axis

The hypothalamic-pituitary-adrenal axis controls the release of cortisol, a key hormone in the stress response.

Allen's Rule

Animals adapted to warm climates have longer limbs for heat dissipation, while those in cold climates have shorter limbs to conserve heat.

Genetic Diversity within Racial Groups

There is greater genetic diversity within racially defined groups than between major geographical distributions.

Acute Stress Response

A rapid mobilization of energy and physiological changes in response to immediate stressors.

Immanuel Kant's classification of race

Kant classified people based on visible differences like skin color and hair texture, mistakenly linking these traits to behavioral characteristics and arguing for fixed categories.

Monogenism

The belief that all human races originated from a single source, with variations attributed to environmental factors.

Anthropometrics

The measurement of human body features, historically used to distinguish between racial groups.

How does the environment influence human physical traits?

Environmental pressures can select for certain traits, leading to similar physical characteristics appearing in different populations independently.

What is genetic determinism?

The idea that genes alone determine physical appearance and identity, ignoring environmental and epigenetic factors.

Genetic determinism

The belief that genes solely dictate physical appearance and identity, which overlooks the influence of environmental factors and epigenetics.

Founder effect

The reduced genetic diversity that occurs when a population is descended from a small number of colonizing ancestors.

Time scales of adaptation model

Categorizes biological responses to environmental changes based on the duration of exposure, from immediate allostasis to long-term genetic adaptation.

Race vs. ethnicity

Race is primarily based on perceived biological markers, while ethnicity incorporates cultural elements such as language, religion, and social affiliations.

Negative effects of UV radiation

Include sunburn, skin cancer, premature aging, and degradation of folate, which is essential for cell function.

Epidemiological transition

The shift from infectious diseases being the primary cause of mortality to chronic diseases in post-transition societies.

Impact of genetic ancestry tests

Can mislead individuals into believing their genes solely define their identity, neglecting the importance of social and cultural factors.

Social determinants of health

Encompass factors such as economic stability, education, and community context that influence health outcomes.

Environmental factors and genetic diversity

Can lead to differential survival and reproduction, shaping genetic diversity through mechanisms like natural selection and adaptation.

Health implications of metabolic health

Refers to the risk of developing diseases like cardiovascular disease and type 2 diabetes, often influenced by body fat distribution and overall health.

Variation of social determinants in urban environments

Can vary dramatically, impacting access to resources and health outcomes among different populations.

Adaptations in high UV radiation areas

Populations often have darker skin due to higher eumelanin levels, which protect against UV damage.

Effects of psychosocial stress on health

Can lead to elevated cortisol levels, which may result in metabolic diseases and other health issues due to chronic stress exposure.

Body response to acute stress

Mobilizes energy, increases heart rate and blood pressure, and inhibits non-essential functions like growth and reproduction.

Acclimatization

Physiological adjustments made by individuals over time to adapt to new environmental conditions, enhancing survival and function.

Genetic drift

The random fluctuation in gene frequencies within a population, which can lead to changes in genetic variation over time.

Visceral and subcutaneous fat

Visceral fat is located near organs and is associated with inflammation, while subcutaneous fat is found under the skin and is generally less harmful.

Role of the microbiota in the immune system

Plays a crucial role in immune system function, influencing responses to pathogens and maintaining overall health.

Embodiment in health

Refers to how individuals biologically incorporate their social and material environments from conception to death, affecting their health outcomes.

Significance of melanin in adaptation

Protects against harmful effects of UV radiation and varies in type and concentration among populations based on environmental exposure.

Allostasis

Allostasis is the process of achieving stability through change in response to stressors.

Homeostasis

Homeostasis is the maintenance of a stable internal environment.

Prenatal exposure

Prenatal exposure to environmental conditions can significantly influence the health risks faced by individuals throughout their lives.

Intergenerational inheritance model

The intergenerational inheritance model examines how maternal health impacts fetal and childhood health, influencing disease risk in adulthood.

Fight-or-flight response

The fight-or-flight response is an autonomic reaction governed by the sympathetic nervous system that prepares the body to either confront or flee from stressors.

Human energy allocation model

The human energy allocation model illustrates how individuals distribute limited energy resources between maintenance and production functions to optimize survival.

Race in biological context

Race is often incorrectly viewed as a biologically determined category, while it is actually a socially constructed concept with more genetic diversity within groups than between them.

Cortisol

Cortisol is a stress hormone produced by the adrenal glands that regulates metabolism, immune response, and helps manage stress.

Autonomic nervous system and stress

The autonomic nervous system regulates involuntary bodily functions and responds to stress through activation of the sympathetic system, enhancing readiness for action.

Acute stress response

The acute stress response involves rapid physiological changes, such as increased heart rate and energy mobilization, to address immediate stressors.

Four time scales of adaptation

They are allostasis (seconds to hours), acclimatization (days to months), developmental adaptation, and genetic adaptation.

Acclimatization

Acclimatization involves physiological adaptations to new environmental conditions that occur over days or weeks.

Biological adaptation

It is the process of change in physiology or morphology resulting from an altered environment, aimed at improving evolutionary fitness.

Genetic adaptation and natural selection

Genetic adaptation occurs through natural selection, leading to heritable changes in a population's genetic code that enhance survival.

Impact of stress on autonomic nervous system

Stress activates the sympathetic nervous system, leading to physiological changes that prepare the body for 'fight or flight' responses.

Fight-or-flight response effects

It triggers the release of epinephrine and norepinephrine, leading to increased heart rate and energy mobilization.

Developmental adaptation

Developmental adaptation describes physiological or morphological changes that occur during growth in response to environmental conditions.

Difference between homeostasis and allostasis

Homeostasis maintains a stable internal environment, while allostasis adjusts physiological parameters in response to external stressors.

Stress and metabolic health

Chronic stress can lead to poor metabolic health by increasing the risk of conditions such as obesity and diabetes.

Genetic drift

Genetic drift refers to random fluctuations in gene frequencies within a population, which can affect evolution over time.

International biological program

It explores the diversity of environments people live in and how these environments affect their health outcomes.

Psychosocial stress in health

Psychosocial stress can lead to allostatic responses that impact physiological function and overall health.

Psychosocial stress

Can lead to allostatic responses that impact physiological function and overall health.

Founder effect

Leads to reduced genetic diversity in populations descended from a small number of ancestors, impacting adaptability.

Intergenerational inheritance of health model

Emphasizes the relationship between maternal health, fetal health, and adult health, highlighting how prenatal and infant exposure to environmental conditions can influence the risk of disease in adulthood.

Poor metabolic health

Often indicated by conditions such as hypertension and is associated with increased risk of cardiovascular disease and type 2 diabetes.

Autonomic nervous system

Comprises the sympathetic nervous system, which activates stress responses, and the parasympathetic nervous system, which promotes relaxation.

Chronic stress

Can result in elevated cortisol levels, leading to metabolic disturbances and increased risk of various diseases.

Human energy allocation model

Posits that individuals must divide their finite energy budget between maintenance of bodily functions and production related to growth and reproduction.

Immune system

Protects against pathogens and is essential for maintaining overall health through innate and adaptive responses.

Gut microbiota

Aids in immune function and metabolic processes, playing a critical role in overall health.

Adipose tissue

Includes subcutaneous adipose tissue, which is less harmful, and visceral adipose tissue, which is associated with negative health outcomes.

Hygiene hypothesis

Suggests that a lack of early exposure to pathogens may lead to inappropriate immune responses and increased autoimmune diseases.

Cortisol

Regulates metabolism, immune response, and energy levels, and is released during stress to help the body cope.

Epidemiological transition

Is the shift from infectious diseases as the primary cause of mortality to non-infectious chronic diseases in post-transition societies.

Environmental factors

Can influence human physical traits, leading to adaptations in traits, such as skin pigmentation, influenced by UV radiation exposure.

Visceral fat

Is located near organs, produces inflammatory molecules, and is associated with higher health risks compared to subcutaneous fat.

Melanin

Protects against UV radiation effects and plays a crucial role in the adaptation of populations to varying UV exposure levels.

UV radiation

Can cause skin damage, sunburn, and increase the risk of skin cancer, while also facilitating vitamin D production.

Brown adipose tissue

Generates heat through non-shivering thermogenesis, playing a role in thermoregulation.

Acute stress responses

Include increased heart rate, elevated blood pressure, rapid breathing, and energy mobilization while inhibiting energy storage and growth processes.

Psychosocial stress effects

Can lead to chronic health issues, including metabolic diseases, by affecting hormonal balance and immune function.

High altitude adaptations

Include increased breathing rate, higher hemoglobin concentration, and enhanced lung capacity to cope with low oxygen levels.

Acute mountain sickness

Is a condition that occurs when individuals rapidly ascend to high altitudes, characterized by symptoms like headache, nausea, and dizziness.

UV radiation exposure and melanin production

Are related, as increased UV exposure stimulates melanin production.

Higher UV radiation exposure

Stimulates increased melanin production, providing protection against UV damage and resulting in darker skin pigmentation.

Allostasis

The process of achieving stability through physiological or behavioral change in response to stressors.

Acclimatization

Physiological adjustments that occur in response to environmental changes over days to weeks, allowing individuals to maintain function.

Innate immunity

Includes physical barriers like mucosal membranes, antimicrobial proteins, and various blood cells that provide immediate defense against pathogens.