Modern Human Variation and Adaptation Flashcards
Biological determinism
cultural and biological variations are inherited in the same way
eugenics
“race improvement” through forced sterilization of members of some groups and encouraged reproduction amongst others
meaning of race in human biology
race has no real meaning, in any racial group there will be individuals who fall into the normal range of variation for another group or one of several characteristics
polytypic species
a species composed of local populations that differ in the expression of one or more traits
are humans polytypic
yes
for a polytypic species, even within local populaions, theres a great deal of
genotypic and phenotypic variation between individuals
what are the four levels of adaptation?
genetic
developmental
acclimatization (physiological)
Cultural (behavioural)
what is the most climatically dispersed species?
humans
human variation is the result of
adaptations to environmental conditions
three levels of physiological response to environment
short term
long term
acquired
long term physiological response
evolutionary changes characterize all individuals within a population or species
ex. bipedalism
short term physiological response
temporary physiological response is called acclimation
ex. sweating or shivering
acquired physiological response
longer term adaptive responses are called acclimatization
ex. increased lung size and RBC count for populations living at high altitudes
homeothermy
complex evolved physiological mechanisms to maintain a constant body temperature, done by mammals and birds
homeothermy allows for the development of…
complex brains
bergmanns rule
body mass tends to be greater in populations that live in cold environments
allens rule
limb length tends to increase in hotter climates and decrease in colder climates
long term adaptation to heat evolved in our ancestors
sweat glands (fur covered animals dont have these- thus they are linked to are lack of fur) vasodilation
allens and bergmans rule are true from
all mammalian species
for heat retention the perfect body shape would be
a sphere
rationale behind allens and bergmans rules
because heat is lost at surface, greater mass allows for greater heat retention and reduced heat loss
longer limbs have more surface area and thus are able to radiate off more heat and cool off quicker
allens and bergmans rule combined
as mass increases the relative amount of surface area decreases proportionately
examples of allens and bergmanns rules
elongated arms and limbs in populations close to the equator
inuits are shorter and rounder
skin colour is a
evolution to solar radiation stress
cold adapted people have…
sustainable patterns of vasoconstriction and shivering that also maintain bloodflow
5 climate adaptations to cold stress
vasoconstriction shivering elevated basal metabolic rate clothing and shelter (cultural) allens and bergmans rules
in areas where food resources are limited or sporadic, people tend to evolve towards…
relatively short statures
need less food
function of melanin
blocks UVB rays and protects DNA in cells from being damaged
how is melanin production incited
UVB rays trigger melanocytes which then produce melanin
more solar stress= more triggered melanocites = more melanin production
we create our own vitamin D, but it requires
solar radiation
why is lighter skin adapted to colder climates
because it allows for more solar radiation in and thus a sufficient amount of vitamin D will be produced- avoids things such as rickets
Uv radiation helps synthesize vitamin D, but depletes…
folic acid, which is necessary for DNA synthesis and spinal development
selective advantages of dark skin
protects from folate degredation
especially important for pregnant mothers
also protects from skin cancer and sun burn
cancer was probably not a huge factor in human evolution since
Most get it after having children
adaptations to high altitudes
larger lungs and greater RBC production (helps oxegenate tissues bettwe even when not much is available)
smaller body size
ability to consume milk after the infant stage is a
human biocultural adaptation
polymorphisms
characteristics with different phenotypic expressions
a genetic trait is polymorphic if…
the locus that governs it has two or more alleles
geneticists use polymorphisms as a tool to understand…
evolutionary processes in modern populations
evolutionary processes can also be understood within a __________ context
cultural
Wolff’s law for skeletal adaptation
bone is not a static structure- it is a living organism that responds to stress and lack of use
stresses can tell us how they were used
how did culture impact the rise of the sickle cell allele
slash and burn agricultural practices resulted in rainwater being left to stand in stagnant pools and thus mosquito breeding areas close to human settlement
rise in malaria and thus rise in sickle cell allele
in all mammalian populations, infants and young children are able to digest
milk
what happens to the gene that codes for lactase production as a mammal ages
usually it is switched “off” in adolescence since its weird for mammals to drink milk after infancy
the geographical distribution of lactose tolerance is related to…
a history of cultural dependance on fresh milk products
closely related to populations whose ancestors herded milk producing animals
