1: Evolutionary Influences on the Body
- Page ID
- 297604
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Bioanthropological Perspectives on Health
By Amanda Feldman
Clinical Perspectives
- The following sections include information on clinical perspectives on evolutionary influences
- Information about the health impacts on populations change as we learn more over time and seek to improve our understanding
- However, how might cross-cultural knowledge and perspectives challenge or add to these discussions? As we go through the course, The Routledge Handbook of Medical Anthropology and other readings on Canvas will help us examine these topics further!
Homeostasis
- Self-regulating processes that maintain stability in the body
- Ex: sweating when hot, shivering when cold, etc.
- Disease is considered a homeostatic imbalance
- Stress – any factor which interferes with normal limits of operation
- Plasticity – ability to respond physiologically or developmentally when exposed to particular environmental conditions
Levels of Organization
- Cells – consist of molecules that form fluid and organelles
- Tissue – group of cells that work together to perform a function
- Organ – consists of two or more tissues
- Organ system – two or more organs work together to perform a set of functions
- Organism – organ systems work together to allow for the individual to function
- Population – group of organisms living in the same place at the same time
Evolution
- Change in the inheritance of traits in a population over successive generations
- Basically…
- There is genetic variation in a species (not all individuals look the same)
- Individuals are born with traits that have been passed down from their parents
- There is change in the trait frequencies (how common traits are in a population)…some traits are being inherited more often than they used to be inherited
- Organisms cannot involve; Evolution is a change in the population
Forces of Evolution
- These forces can cause evolution to happen:
- Natural selection – differential survival and reproduction of individuals due to differences in phenotype
- Phenotype is the outward appearance of the trait; Genotype refers to the genetic makeup of the trait
- Mutation – alteration in the nucleic acid sequence of DNA
- Genetic drift – loss of genetic variation that occurs due to chance
- Gene flow – transfer of genetic material from one population to another
- Sexual selection – traits are passed down due to mate choice; they do not necessarily improve survival
- Artificial selection – selective breeding to develop particular phenotypic traits
Primate Evolution
- There are 3 types of mammals:
- Monotremes – egg-laying mammals
- Marsupials – partial internal development; offspring continue to develop in external pouch
- Placentals – embryonic development is completed internally
- Primates are an order of mammals (placental mammals)
- Humans are one among many primate species
Primate Characteristics
- Arboreal adaptation
- Omnivorous, many have tendency towards frugivory
- Large brains, social complexity
- Greater dependence of learned behavior
- Emphasis on vision, decreased snout and olfactory areas
- Forward-facing eyes
- Postorbital bar or postorbital closure
- Upright posture
- Retention of clavicle
- Flexible limbs
- Grasping hands (prehensile)
- Dexterity
- Opposability
- Nails instead of claws
Homo sapiens
- Humans date back to ~195,000 years ago
- Current evidence suggests humans migrated out of Africa into Eurasia
- Hot climate adaptations
- Sweat glands
- Loss of body hair
- Melanin adaptations
- “Generalist specialist” species
- Ability to create complex, specialized tools
- However, not limited by one lifestyle; flexible lifestyles and ability to create a wide variety of tools
Human Skeletal Characteristics
- Foramen magnum is centered
- Forward facing temporal
- Small canines (small teeth, overall)
- Parabolic dental arcade
- S-shaped vertebral column
- Bowl-shaped pelvis
- Femur is slightly angled inward
- Big toe is in-line instead of opposable (non-grasping foot provides better support for bipedalism)
- Legs are longer than arms (arms are not used for walking)
- All primates have opposable thumbs, but humans have longer thumbs and more flexible hands
- Precision grip and fine motor control
- Large frontal bone (forehead)
- More delicate, gracile features in the skull (smaller brow ridge, smoother surface)
Neolithic Revolution
- Mesolithic age
- Pre-agriculture
- Hunting and gathering
- Neolithic age (~10,000 years ago)
- “Neolithic revolution”
- Agriculture, domestication, farming societies
- Bow and arrow
- Methods of warfare
- “Neolithic revolution”
Hunting and Gathering vs. Agriculture
- Hunting and gathering
- Pros: wider variety of food sources, more sustainable relationship with environment, more leisure time
- Cons: cannot support large population, nomadic, changing food source availability
- Agriculture
- Pros: can support population growth, ability for permanent residences, surplus food production, lead to adaptations for lactose tolerance and malarial resistance
- Cons: limitations in diet, malnutrition, requires a lot of work to sustain, ecological impacts, social stratification between classes, disease exposure, sanitation problems
Industrial Revolution
- 1760-1840
- Scientific and technological advancements
- Shifted away from hand production methods to use of machines
- Impacts:
- Rickets and vitamin D deficiency
- Repetitive tasks
- Poor sanitation and disease epidemics
Effects of Bipedalism
- It is rare for other mammals to have scoliosis (more common in humans)
- Bipedalism means weight is redistributed throughout the body (and gravity affects the wear and tear on joints)
- Narrow pelvis (due to bipedalism) and large brain size in infants affects childbirth
- In some human populations, back pain is not common
- Pain contributors:
- Sedentariness
- Diet, lifestyle, and stress impacts the body
- Specialization in occupation leads to people doing a lot of repetitive body movements for long periods of time (ex: carpal tunnel)
Back Pain
- Vertebrae – mostly spongy bone; discs between vertebrae provide cushioning
- Lower back pain most common; more common in child athletes
- Possible causes:
- Fractures
- Hernias – disc breaks or is squeezed
- High prevalence in bioarchaeological record – carrying heavy loads, horseback riding
- Genetic predisposition
- Osteoarthritis – wear on cartilage in joints
- Spondylosis – fractures in vertebrae
- Spondylolisthesis – slipped discs
- Stenosis – compression of spinal column, might compress nerve
- However, back pain is more likely not related to bone but is related to muscle pain
- Often influenced by:
- Stress
- Depression
- Work satisfaction
- Chronic pain
- Smoking (affects bone and is associated with several other effects on the body)