anth 196l lab 6

*did not turn in- take answers with a grain of salt*

conditions necessary for evolution

variation, inheritance, selective pressures

what conditions was Dr. Jablonski sure about

sure about variation and heritability

humans have a visible range of skin color- from different types of melanin

investigating the origins of this variation

Dr. J’s hypothesis

as humans evolved, we lost hair on our bodies, which increased melanin to protect from UV rays

if this is correct, we will see more melanin in populations that have more sun (more pigmented skin)

populations that experience less sun will less pigmented skin

patterns of UV radiation variability across the globe

closer you get to the equator, more UV rays

further you get, less UV rays

more UV rays at higher elevation

data that Dr.J would expect to find

confirms Dr. J’s hypothesis

general curve is that the further a population gets from the equator- the lighter their skin is

propose a mechanism that UV radiation might pose as a selective pressure on humans leading to evolution of darker skin

risk of skin cancer or other diseases caused by UV radiation (disproven)

higher visibility if sunburned

why would Dr. J be suspicious of the hypothesis that UV radiation is linked to skin melanomas?

cancer happens usually at a later stage in life, after people have reproduced-genes for cancer are therefore not passed on

doesn’t affect natural selection

what are two ways that a person can become deficient in folate

living in an environment where there is not a lot of plants with vitamin B

not eating enough vitamin B

too much UV exposure

propose a mechanism by which folate might have selected for the evolution of darker skin color

higher melanin protects against deficiency in vitamin B and folate by protecting from UV exposure

birth definancies can affect reproductive success

why aren’t all human populations heavily pigmented

some environments have less UV exposure

UV doesn’t affect them as much

which regions of the world allow lightly pigmented people to synthesize adequate vitamin D from sunlight all year long

closer to the equator and middle regions (dotted and small diagonal lines)

what regions allow adequate vitamin D synthesis for moderately pigmented people

the dotted region

what regions allow for adequate vitamin D synthesis for darkly pigmented people

none of them

do these regions match where people evolved

are people living in areas where they should be able to synthesize vitamin D

no

dark skinned people do have a region that is adequate for them, but they still live in all of these regions

what allows people to survive in regions of the world that do not allow for synthesizing

diet

fish, animal proteins, vitamin d plants

why are all populations darker than predicted in order to achieve optimal levels of vitamin D from sunlight

need to produce more folate to get more UV

why are women usually less pigmented than men

increased need for higher amounts of vitamin D when pregnant and breastfeeding

trying to maximize UV absorption