View
216
Download
0
Category
Preview:
Citation preview
Problems of survival (3): Diet and the omnivore’s dilemma
The human diet
I forager vs. chimp diet
I cooking
I recent evolutionary changes
Solving the omnivore’s dilemma
I sweet and bitter tastes
I learning biases: neophobia
I taste-aversion learning
I social learning
I culture (spices and cuisine)
Human forager vs. chimp diets
vert. nuts/ othermeat roots seeds fruits plant insects
Onge 79 19 0 0 0 2Anbarra 75 8 0 4 0 12Arnhem 77 19 0 0 0 3Ache 78 0 0 1 9 11Nukak 41 0 0 40 0 20Hiwi 75 15 0 5 2 3Gwi 26 37 0 37 0 0Hadza 48 30 0 15 0 0
CHIMP 2 0 5 60 29 4
Dietary percentage of foraged foods, from Kaplan et al. 2000
The advantages of cooking
Change in digestibility from cooking:
Starch source Raw Cooked % increase
Wheat 71 96 34%Oats 75 96 28%Barley 93 99 6%Green banana 49 97 96%Plantain 54 100 87%Potato 97 51 91%Pea 80 91 14%
(from Carmody and Wrangham 2009)
Recent changes: Lactase persistence
I evolved in dairy farming communities in central Europe
I first evolved about 7500 years ago
I evolved independently in Africa and Middle East
Recent changes: Amylase copy number
I amylase digests starch in saliva, varies by copy number
I more copies means more amylase
The Omnivore’s Dilemma
The human diet
I forager vs. chimp diet
I cooking
I recent evolutionary changes
The omnivore’s dilemma:
I which foods are toxic?
I which foods are most nutritious?
I how can we know?
Solving the omnivore’s dilemma: sweet and bitter tastes
I newborns react more positively to sugar solutions than water
I most infants dislike bitter and sour tastes
I around 4 months, infants develop liking for salty tastes
reaction of a two-week old baby to taste of sugar and lemon juice
Solving the omnivore’s dilemma: Neophobia
I rats are also food neophobic; eat a small amount at first
I willingness to try new foods is greatest during the first twoyears
The omnivore’s dilemma: Social learning
I young rats prefer foods mothers ate when pregnant andnursing
I young rats forage where adults are foraging
I adult rats prefer food if have smelled on breath and body ofother rats
I howler monkey infants: copy mom when eating leaves, notfruits
The omnivore’s dilemma: Social learning
I young rats prefer foods mothers ate when pregnant andnursing
I young rats forage where adults are foraging
I adult rats prefer food if have smelled on breath and body ofother rats
I howler monkey infants: copy mom when eating leaves, notfruits
The omnivore’s dilemma: Social learning
I young rats prefer foods mothers ate when pregnant andnursing
I young rats forage where adults are foraging
I adult rats prefer food if have smelled on breath and body ofother rats
I howler monkey infants: copy mom when eating leaves, notfruits
The omnivore’s dilemma: Social learning
I young rats prefer foods mothers ate when pregnant andnursing
I young rats forage where adults are foraging
I adult rats prefer food if have smelled on breath and body ofother rats
I howler monkey infants: copy mom when eating leaves, notfruits
The omnivore’s dilemma: Learning in utero
Babies’ intake of carrot-flavored cereal compared to plain cereal
(from Mennella et al. 2001)
The omnivore’s dilemma: Social learning
I human babies more likely to take novel food from mom thanstranger
I human babies more likely to take novel food from stranger ifstranger eats first
I human babies choose food eaten by actress speaking theirown vs other language
The omnivore’s dilemma: Social learning
I human babies more likely to take novel food from mom thanstranger
I human babies more likely to take novel food from stranger ifstranger eats first
I human babies choose food eaten by actress speaking theirown vs other language
The omnivore’s dilemma: Social learning
I human babies more likely to take novel food from mom thanstranger
I human babies more likely to take novel food from stranger ifstranger eats first
I human babies choose food eaten by actress speaking theirown vs other language
Summary
The human diet
I humans depend more on meat and extracted foods than otherprimates
I human diet is more nutrient-dense
I human foods are hard to acquire (brain evolution?)
I cooking is universal, increases available nutrients
I humans are evolving adaptations to cultural dietary changes
The omnivore’s dilemma: how to choose safe, nutritiousfoods?
I taste preferences in newborns
I neophobia (especially high among toddlers)
I babies prefer what mother ate (learning in utero)
I children prefer what familiar people eat
I cultural traits can be fitness-enhancing (spices)
Summary
The human diet
I humans depend more on meat and extracted foods than otherprimates
I human diet is more nutrient-dense
I human foods are hard to acquire (brain evolution?)
I cooking is universal, increases available nutrients
I humans are evolving adaptations to cultural dietary changes
The omnivore’s dilemma: how to choose safe, nutritiousfoods?
I taste preferences in newborns
I neophobia (especially high among toddlers)
I babies prefer what mother ate (learning in utero)
I children prefer what familiar people eat
I cultural traits can be fitness-enhancing (spices)
Recommended