Human Biological Variation Midterm
Human Adaptation: Homeostasis and Stressor
adaptations that allow them to change and survive in different environments, the ability to maintain homeostasis is an adaptive success homeostasis (maintain/restore stable internal physiological environment within tolerable limits) stressor (disruption of normal functioning and interferes with homeostasis)
Hardy Weinberg theory of genetic equilibrium: principles and utlity
allele and genotype frequencies in a population must remain constant or are in equilibrium from generation to generation unless specific disturbing influences are introduced
The "eternal triangle": Genotype, Phenotype, and Culture (Paul Baker)
attempts to understand the causes for phenotypic differences in the biology and behavior of human populations phenotype should be conceived as interaction between genotype, physical environment, and culture
phenotypic plasticity and reaction norms
based on the mechanimsm associated with phenotypic plasticity (ability of single genotype to generate a range of phenotypes in response to environmental conditions)
point mutation
change in 1 base pair of DNA
histone methylation
chemical cahnges in chromatin structure that lead to how DNA strands are wrapped around a histone protien
Describing vs. classifying human variation
classification schemes in biology of human diversity as "race" we describe/categorize people based on skin color
exons
coding DNA, transcribed by mRNA and involved in protein synthesis
structural gene
coding sequences code for proteins, which are constructed by amino acids (collagen, enzymes)
haplotypes
combinations of genes or nucleotides in close proximity and inherited as a linked unit
stress and health
direct physio effect through activation of stress response and indirect effects through health relatd behaviors
problem of evolutionary convergence
distantly related populations are similar for certain traits if they evolved under the same selctive pressures
great chain of being
early classifications used this system of the universal heirarchical ladder (implied or explicit rank order of superiority from euro--> asian-->american-->black)
developmental origins of health and disease (DOHaD)
environmental events occurring during sensitive developmental periods that can induce effects on human biology that persist into adulthood
epigenetics
epigenetics (differences in how DNA is read without changes in the DNA itself) epigentic mechanisms 1. DNA methylation 2. Histone methylation
fetal origins moderl (david barker)
fetal undernutition/ permanent physiological programming --> developmental response--> low muscle, insulin resistance, high visceral fat, hypertension--> increased cardiovascular and metabolic disease risk in adulthood
general objectives and timing of developmental plasticity
fine tune an individuals physiology during development to match the local ecological conditions, induce long term adjustments in bio structure and function of the phenotype
Altman bonobo research
foraging in east african dump--> increased size, earlier sexual maturity, enhanced sexual dimorphism
mitochondrial DNA
found in mitochondria, maternally inherited, high mutation rate, high copy number in each cell
isolation by distance
high gene flow btwn geographic close populations human genetic diversity form geographic clines (people tend to be more genetically similar to people who line near them then 2 people who live father away0
Samuel Morton: Cranial Measurement
hypothesis: difference among race particularly among brain size (intellectual capabilites) 1. brain capacity order: english, chinese, SE asian, american indian, african thoughts at the time 1.humans could be divided into fixed number of race 2.moral intellectual capabilities not evenly distributed among races 3.mental capabilites are associated with certain racial features
primate foundations of developmental plasticity
increased bio flexibility in primate systems with long lifespan and slow growth, physio flexability allows enviro tracking
frameshift mutation
insertion or deletion of DNA that leads to misreading of codon
biological programming (david barker)
insult experience during a senstive time of development can affect the growth and organization of specific biological systems
nondisjuntion mutation
lack of seperation between homogolous chromosomes during meiosis when combined with a normal gamete--> leads to extra chromosme
developmental plasticity
long term, irreversible changes that result from exposure to environmental stressors during growth and development
classic markers
mendellian inheritance, protein polymorphisms ex. blood groups
synthetic theory of evolution
merging of natural selection and genetics through mutation
DNA mathylation
methyl groups attach to regions adjacent to specific gene promoters
introns
most non-coding DNA
polygenic
multigene inheritence, traits infleunce by the actions of two or more genes and often produce variation
genetic switches
not actually genes but sections of the DNA that turn nearby genes on/ off
population thinking
not typology
SNP's
occur bz of alteration in single nucleotide via point mutation
polymorphism
occurrance in a discrete gene trait of two or more genetic variations
how race becomes biology: Gravlee's biocultural approach
overfocus on genetics so.... 1. consider multple levels of analysis 2. use developmetnal and life course perspectives 3.look at individual levels of racism 4.look at institutionalized racism
hardy weinberg breakdown
p= frequency of the dominant p^2 = homozygous dominant (RR) q= frequency of the recessive q^2 = homozygous recessive (rr) 2pq= frequency of Rr (heterozygous Rr)
hardy weinberg equation
p^2 +2pq +q^2 = 1 (p+q=1)
Functional Adaptations: Acclimitization and developmental acclimitization/ plasticity
phenotypic changes during the lifetime of an individual to help maintain homeostasis in response to a stressor
anthropometry
physical measurement of the human form
acclimitization
provides important buffering mechanisms to maintain internal stability (homeostasis)
regulatory gene
regulate the timing and expression of other genes, turns DNA on or off ex. HOX gene (highly structured genes that control sequential patterns during development)
Herbert Spencer: social darwanism
scientific racism of applying evolution framework to describe social evolution competition to survive to maintain and improve characteristics of human racial groups
pleitrophy
single gene inheritence that affeccts differet traits
craiometery
size and shape 1. cephalic index (breadth/depth of skull) 2. facial form (progmatic [projecting midface], or orthognathic [straight faced])
Stephen J Gould
the mismeasure man thought morton manipulated data to inform hypothesis on brain size reflected intelligence subconciously
population genetics
the study of how frequency and distribution of alleles, genotypes, and phenotypes within and between populations focus on the change in the genetic composition of populations over time and geographical space
complex or polygenic traits
traits whose properties are controlled by many genes
gene- environment interactions
typically not based on a one-to-one correspondence bwteen genes and expression of traits ex. Tooth crowding and malocclusion (result from changes in diet and food prep, softer food reduces stress on chewing muscles, reducing the underlying bone)
How to address the question of "Are we still evolving?"
until recently no, however yes because of the evolution of food production (malaria, sickle cell, lactose, skin color) evolution is not just natural selection, there are multiple factors (mutation, gene flow, genetic drift, natural selection)
transcription and translation
DNA--> RNA--> amino acids--> proteins
Johann Blumenbach
"father of physical anthropoloy" defined the classical race in 1795 1. 4 group scheme of geography (europeans, asian, american, african) 2. 5 group scheme of physical characteristic (caucasion: white, mongolian:yellow, ehtiopian:black, american:red, malayan: brown) studies skeletal morphology--> the field mves toward focus on the skull and the era of measurement and explicit hierarchy begins
Francis Galton: eugenics
"race improvement" and controlled selective breeding sterillization and anti-immigrant movement natural selection in species as away to improve/control hereditary traits
Modes of biological adaptations (Gabriel Lasker)
* Gabriel Lasker proposed in 1969 science paper that stated 1. human biology has a repertoire of adaptive processes or "modes" that allow for adjustment to environmental change 2. humans must cope with ecological change that occurs on multiple levels and timescales
early scientific approaches to human variation
1. Carolus Linneaus 2. Johann Blumenbach
Types of human adaptation: Cultural/behavioral and biological
1. cultural/ behavioral tools, tech, language, medicine, subsistence strategy and diet, aspects of culture can be adaptive by increasing survival and fitness 2. biological
3 modes that allow for adjustment to environmental change
1. darwinian or genetic adaptors 2. acclimitization 3. developmental plasticity
human genetic variation and the concept of race
1. human genetically extremely homogenenous 2. human racial classification based on diff criteria are nonconcordant (diff traits= diff clustering) 3. evolutionary convergence
hardy weinberg 5 condition
1. matins is random with respect to the trait being studies 2. mutation is not occurring at the locus being studied 3. the population is infinite which limits the possibility of random genetic drift 4. no migration in or out of the population, thus no gene flow 5. natural selection is not acting on the trait being studied
Key events leading to fall of race concept
1. modern synthesis 2. sherwood washburn "the new physical anth" 3. population thinking 4. Human developmental plasticity and secular trends
monogenesis vs. polygenesis
1. mono -human race were the result from chances in a single origin 2. poly -races were seperate bio species and emphasized heirarchy (multiple humans with diff species: race)
Rise of Race concept
1. most early studies of human variation were focused on description and classification not understanding 2. physcial anthro begins as technique to describe an classify modern humans 3. early studies of human var shaped european colonialism and ethnocentricism 4. evolutionary theor provides a framework for understanding human var, early attempts were problemative
evolutionary forces shaping genetic variation
1. mutaiton 2. gene flow (increased genetic variation within populations and decreased genetic variation between populations) 3. genetic drift (decreased genetic variation within populations and increased genetic variation between populations) 4. natural selection
key factors to stress and health
1. percieved lack of control 2. lifestyle inconguity 3. lack of social support 4. inability to acheive full social engagement
Types of genetic and DNA markers
1. polymorphisms 2. classic parkers 3. complex or polygeneic traits 4. SNP's 5. Haplotypes
Genetic/Darwinian Adaptations
1. reflects natural selection, developed over many generations (measured through fertility and mortality) 2. expected when enviromental stressors due present over long period of time, stressors cant be buffered using other means limits the ability to make future changes in physiology of morphology
continuous variation and nonconcordance
1. variation typically continuous in most traits of interest to those studying traits 2. nonconcordance (diff traits lead to diff pop groups, but they vary independently of each other--> thus choice is arbitrary)
carolus linneaus
1758 used a systematic attempt at assigning varieties of race (homo sapiens, hs. americanus, hs. europeous, hs asaiticus, hs ferus, hs montrous) used a form of biological determinism by traits like skin color, head size & shape, facial shape, geography, and percieve intelligence and behavior to categorize
modern synthesis
1930/40's started with synthetic theory of evolution, and bridged macro and micro evolution turing the focus onto populations focus on pop: watched variabel populations to see that change in allele/gene frequencies over generational time and populations evolve not individuals
Sherwood Washburn: the new physiccal anth
1951 sought to bring physical anth into the realm of modern synthesis by changing perspective and moving from methods and classsification to processes of mechanization of evolutionary cahnge unifying theoretical framework for understanding human variation and change through time
Frank Livingstone: "On the non-existence of human races"
1962 suggests the focus on clinal variation in geography other then the unchanging view of discrete racial groups is inconsistent with out knowledge of human adaption and evolutionary change
Richard Lewontin: patterning of genetic variation
1972 looked at allele frequencies within and wout of populations to understand genetic change of variation 1. variation btwn races (10) 2. variation brwn pop (5) 3. variation within pop (85) race no longer valid because variation in the population is the highest
human developmental plasticity: franz boas and secular trends
Franz boas 1. Immigration studies 1912 2. elements from environment effect growth and development, the plasticity of the human , not just in weight and height but also in cranial shape (facilitated the demise of the race concept because markers that were once thought as set were not plastic) secular trend 1. change in phenotype occur over generational time
general adaptation syndtrom
Hans Seyle the ability to return to homeostasis unless ongoing stress then exhaustion