evolution and the human body Flashcards
what are some examples of why evolution does not make perfect organisms
- historical constraints: NS uses existing structures/genetic variation engineers don’t, pandas thumb
- adaptations are compromised: peacock’s tail attracts females but avoids predators
- NS works with available variation: best rather than ideal, slight imperfections are the sign of NS
- Mismatches between our genes and rapidly changing environments during last 10,000 yrs - e.g. obesity
what animals have poor colour vision and give an example
nocturnal primates; tarsiers
when did colour visions develop
as monkeys and apes became diurnal
what skills do monkeys and apes have with respect to vision
they can distinguish young vs old leaves and types of fruit
what % of myopia in the west vs asia
30-40% in the west
70% in asia
why does asia have a high rate of myopia
eyeball length is long
what % of HGs had myopia
<3%
what % of myopia in 19th century Denmark farmers, craftsman, and university students
3%: farmers
12%: craftsmen
32%: university students
in the 1960s what % of Inuit elders had myopia compared to most school children
<2%
what are two hypotheses of the causes of myopia
- common close focussing causes the eyeball to elongate as children (no experimental support in humans)
- lack of normal visual input cause myopia in monkeys (children who spend more time indoors get myopia independent of reading, and complex visual input may be needed for normal eyeball elongation)
was myopia low in the paleolithic era
yes
what would have happened if myopia existed in the paleolithic era
would have negatively impacted skills as HGs
what skills can you have with poor eyesight
specialized tasks like close work, art, crafts, etc
what is the connection between NS and glasses
glasses shield us from the effects of NS
how are photoreceptor cells installed in vertebrate eyes
backwards
where are photoreceptor cells located
on the outside
where does wiring in the vertebrate eye face
the light
what does our backwards eye promote
retinal detachment
blind spot
where does the recurrent laryngeal nerve run from
it runs from the brain to muscles of the larynx
what does the laryngeal nerve do
allows us to speak
is the laryngeal nerve’s link direct
no
it loops under the aorta: 3x longer than needed
where did we inherit the laryngeal nerve wiring
from fish: gills, heart, and brain are closely packed
what animals have a poorly constructed laryngeal nerve system
ostrich: 1 m long neck
giraffe: 5 m long neck
brachiosaurus: 10 m long neck
how do we breath and eat
there is one tube from the mouth for both breathing and eating: ancient vertebrate adaptation
