Human evolution Flashcards
what factors have effected human physiology
natural disasters effected evolution
species development slightly due to adaptation to climatic conditions
what happened to make humans dominant
cooking gave humans advantage
- requires fire
some toxins in fresh foods
was selection of the fittest the reason for human dominance
difficult to validate
what is an example of toxins in fresh food
cassava - staple for millions S America, Africa
many African cassava contain cyanide, toxic unless processed correctly
how is cassava processed properly
cut roots small pieces
boil in open pan - dont stand over it as HCN blinds
leave 2-3days so HCN volatilise
what causes toxins in cooked foods
heat causes significant chemical change - creates some molecules known to be toxic
what is an example of toxin produced when food is cooked
what is it produced from
acrylamide
from amino acid asparagine (potato contains this)
what are the benefits of eating raw meat and plants
high vitamin levels higher fibre content pick and eat weight loss modern raw food has oil - responsible for 30% energy
what are the cons of eating raw meat and plants
lot of chewing - lot energy used digestion difficulty - lot energy used high bacterial load pathogens toxic compounds short shelf life seasonal availability 33% chronic energy deficient
what was the effects of cooking food on the physiology of ancient humans
chewing - delivered small particles to stomach so less energy and less time
digestion of protein and polysaccharides improved
starch gelatinised - easier amylase digestion, more energy release
proteins more soluble, smaller food = easier protease digestion, more efficient nutrient uptake
longer shelf life
what causes a longer shelf life on cooked foods
smoke presence
lower water activity
decreased microbial load
what is the effect on collagen when cooked
triple helix structure unwinds
form gelatin which is water soluble and nutritious
what is the effect on fat when cooked
fat soluble vitamins dissolved in oil droplets in food
protects vitamins from oxidation
assits gut uptake
what is the effect on pathogenic bacteria when cooked
heat 72 degrees+
decrease microbial load
what is the effect on plant tubers when cooked
softens the many hard roots by hydrating the tissue and modifying cell walls
what is the effect on starch when cooked
gelatinises starch, easier to break amylase in the gut, increasing sugar supply
what is the benefit of cooking water
make use of soluble vitamins
what are the benefits on cooked food
more energy to hunt and gather food
increase fertility
time to relax - sheep and cows eat grass most of day for enough
how quickly do species react to environmental changes, example
Darwin studied finches in Galapagos islands (develop his theory of evolution)
islands separated from other species, easy measure effects of environmental change
e.g. drought, relied on hard-shelled seeds so bigger stronger beaks favoured, survive
what are the anatomical changes to mouth and teeth that have occurred due to eating cooked foods
more need for molars, less for sharp teeth
high energy food = less food entering more
fossil and archaeological records = decreasing mouth size, teeth size and type change
what are the anatomical changes to the digestives system that occurred due to eating cooked food
cooked food provide more energy - smaller meal, human stomach small for out weight
large intestine about 60% of that expected - where intestinal microbes break fibrous materials like resistant starch and non-starch polysaccharides
amylase more important due to increased gelatinised starch
which part of animal contains most energy
liver kidneys
most energy in fast way
what did homohabilus do for safety
slept in trees
was a climber
what did homoerectus do for safety
not strong enough arms to climb
had fire to scare
