Tem

Silverton, Jonathan. Dinner with Darwin, Chapters 5-8

• 5: Soup

• Umami (savory)

• 1909 Kikunae Ikeda. broth of dried bonito and seaweed. discovered the flavor linked to glutamic acid. salts of the same - sodium glutamate - MSG.
• evo-expl for glutamates in seaweed. through osmosis, maintains cell hydration in saline environment.
• [Dashi So, what is Dashi?]
• glutamates also in tomatoes and parmesean cheese -- pasta marinara explained.
• Why do we taste umami? Marker for protein and nutrients. breast milk 10x glutamate of cow milk.
• Isn't MSG just salt? 58: salt not detected below 1:400. socium glutamate detected to 1:3,000 - umami taste varies. some people just report salt. early 21st century, pair of proteins isolated for umami receptors in tongue.

• Salt

• two salt tasting receptors, one for low concentrations one for high.

• Bitter - green in cabbage family - from glucosinolates - defensive for insects.

• Also, compounds in tea, alkaloids, bitter. also in chocolate, poisons like strychnine and drugs like cocaine.
• Lots of compounds trigger bitter, but also animals vary in range of bitter receptors. cats 6, mice 35, humans 25. Whether bitterness is experienced as good or bad depends upon the "smell image" (brain interaction with tongue/olfactory bulb).

• Sour

• mild acid, in unripe fruit to prevent eating early. sour signals acids that might be dangerous for our cells, but mild sour is pleasant.
• kids 5-9 have heightened sour tolerance. theories 65: encourage nutrient consumption, but why not after 9? or, broadens palette in kids.
• example of individual variation in sour detection. PTC polymorphism - 65 funny story about scientists going to the zoo in Edinburgh 1939 to investigate.

• 6: Fish

• fish smell from TMA, releases ammonia, functions to maintain water balance in live fish.
• Smell

• Is it true that humans have an impoverished sense of smell?

• Differences between taste and smell -- 1. taste has more possibilities: 35 receptors for bitter; 400 for OR (olfactory receptors) -- really 600 with alleles. 2. individual wiring. 70

• Evolutionary explanation: We had less need for smell once we started walking upright. Might make sense to have smell receptors wired like an alarm and taste receptors for lots of information. mice can smell carbon dioxide? wow.
• details comparison to elephants: 2,000 OR. rats and mice about 1,000.
• 72: main discussion of retronasal olfaction - "smell image" (not his term, but in the rno lit) jasmine as sweet - coincidence!
• We have a taste/smell system that can discriminate a trillion smells, more that visual discrimination.
• So, we have an impoverished smell alarm system compared to other animals or our past, but a virtually limitless taste palette.

• back to fish

• how fish swim, fish have myoglobin in stead of hemoglobin. fish store fuel as oil. up to 20% fat in muscle. rapid acceleration from white muscle found in big predator fish.
• fish muscle vs. animal muscle -- taste differences.
• garum -- possibly first industrial food

• 7: Meat

• evidence from tapeworms (3 species) that go back 2-2.5 mya. Shared food chains between lions/antelope or hyena prey. evidence from cave art. Not by meat alone, also evidence of grinding technology 32,000 ya for plant consumption. isotopic analysis of human bones shows food preferences. woolly mammoth also good for housing material.
• Timeline: 72K out of Africa, 40-50k diversity in diet (possibly food/pop dynamic)
• Ohalo II (current Israel): wheat, barley (bread cakes), fish, but also gazelle, grebes, ducks and geese, aurochs, pigs, and goats. But by 12,000 ya evidence of large and small animals scare in arch record.
• food/pop dynamic: live births 5.4 in hunt/gatherers. 9.7 with farming. One of the main products of agriculture is humans.
• domestication stories: modern chicken from red jungle fowl (cross bred with grey jungle fowl for yellow skin color), Asia. Chicken houses of Rapa Nui
• 90: the remarkable navigational skills of the polynesians. what I learned today.... Sheep.... Cattle from Aurochs, but european cattle not descended from European aurochs.
• disgression on "rewilding" - Modern Aurochs
• Fertile Crescent animal domestication was from local stocks.
• Domestication syndrome --- less seasonal breeding, piebald coast, shorter muzzles, smaller teeth, smaller brains, curly tails, juvenile and docile behavior. Demonstrated by Russian wolf breeding experiment to be linked to selection for docility. Possible explanation in the "neural crest" - structure in embryo. docile might also select for other characteristics of the neural crest. still no certain theory.