Some on the eye Myopia: Near sightedness –The image focuses in front of the retina

Pathology of myopia varies Japan -44% of adult pop. U.S. – 20-25% of adults Reading and education level Are risk factors During one of the Chinese revolutions, they killed people with glasses because it meant they had read

Hyperopia Farsightedness At times confused with loss of vision at onset of age Note ostrich eyes are bigger than its brain

Ostriches are ridiculous

Presbyopia Greek Presby: “old person” Theory is that with age the crystallin lens loses elasticity. –Become far sited So they get bifocals –Ben Franklin

Astigmatism defect of the eye, where vision is blurred by an irregularly shaped cornea. A refractive problem Might be able to focus in horizontal plane, but not vertical

Evolution of the Eye Homologous organ First eyes 540 mya “arms race” idea

Adaptation: Birds have better vision Night birds can pick up U.V. Light Euglena bacteria has a light sensitive patch (2) Planarians have eyespots

Is it too complex to evolve piece by piece? –“what good is half an eye?” –Argument from personal belief But there are a lot of sub optimal eyes in nature. Even in people a myopic person has an advantage over the blind. Humans don’t have the best eyes by a long shot The mantis shrimp has eyes divided into three parts; trinocular vision. –We have 4 visual pigments, they have 16. Can pick up U.V. and polarized light

Sea Sickness In Part results from your brain focusing on stable side of boat, waves moving closs, and waves moving far away on the horizon.

Decibels Logarithmic unit, measures sound levels Originally a bell was the amount of sound lost over 1 mile of telephone line

Source of soundSound pressure sound pressure level PadB re 20 µPa immediate soft tissue damage50000approx. 185 rocket launch equipment acoustic testsapprox. 165 threshold of pain hearing damage during short-term effect20approx. 120 jet engine, 100 m distant6–200110–140 jack hammer, 1 m distant / discotheque2approx. 100 hearing damage from long-term exposure0.6approx. 85 traffic noise on major road, 10 m distant0.2–0.680–90 moving passenger car, 10 m distant0.02–0.260–80 TV set -- typical home level, 1 m distant0.02ca. 60 normal talking, 1 m distant0.002–0.0240–60 very calm room0.0002– –30 quiet rustling leaves, calm human breathing auditory threshold at 2 kHz -- undamaged human ears

Ear Wax Cerumen Cleans, lubricates (prevents itching), and protects From sebaceous and apocrine glands Two genetic types: Wet Dominant, Dry: recessive –Asians, Am Indians: Dry –Africans, Europeans: Wet Builds up in whales like rings in a tree Wet type ear wax flouresces under U.V. light

Taste & Smell: Chemical senses

McDonald’s Fries –Win best taste competitions –Not the method, potatoes, or machinery –Taste of fried foods determined by cooking oil –McD’s uses 7% cottonseed oil, 93% beef tallow: a fry has more beef fat/ oz than a burger –McD’s world locations 

Obviously there was criticism McD’s changed to pure veg. oil 1990 Problem: how to make them taste like beef without using beef? “natural flavor” –Explains why most of our food taste the way it does.

Natural Flavor vs. Artificial Flavor Both are man made 90% of our food $ is for processed food Canning, freezing, & dehydrating destroy flavor Big money in making flavor Name food brands Name the companies that makes flavor

International Flavors & Fragrances (IFF) World’s largest flavor company –Also makes smell of best selling perfume’s, deodorant, and soaps –2005: 1.9 Bil. Givaudan: 2 nd Haarman & Reimer: Largest German Takasago: Largest Japanese

Smell owns taste Aroma can be 90% of a food’s flavor What evolutionary benefit would organisms with a better sense of smell have? –Find food –Distinguish good food from bad Evolution puts pressure on us.

Flavors vs. smells Taste buds can detect ~ 5 basic flavors –Sweet, sour, bitter, salty, astringent, umami –About 4-10K taste buds on tongue, cheek, pharynx, epiglottis –Bumps called papillae Olfactory system can percieve thousands of different chemicals

Mastication releases gases Thin layer of nerve cells called olfactory epithelium receives gases and transduces them into smell signals Brain combines smells signals with simple taste signals and decides if its something you want to eat.

Food preferences & personality form early in life Babies will adjust to hot & spicy, bland health food, or fast food depending on what the people around them eat. Baby eating sushi

We don’t know it all yet Psychosomatic effects happen Color of food can determine perception of its taste People can grow accustomed to bad smells. –Come back from a long vacation and immediately take a good whiff of what your house smells like. Other people smell that whenever they visit you

Aroma & memory Nerve signals for smell go right past parts of our brain associated with memory. –Smelling salts (ammonium carbonate can wake you up by causing an inhalation reflex –Smells can bring back memories –Comfort foods –McD’s makes billions on this (Happy Meals)

Flavor in history Empires built, seas crossed, religions and philosophies changed over taste. Columbus went looking for flavor Salzburg Germany: Founded to protect salt trade Saffron is 12$ a gram

So artificial flavors cropped up from perfume companies after canning started German scientist playing with chemicals: suddenly lab smells like grapes  methyl anthranilate  grape Kool-Aid  purplesaurus rex

1.4 Bil a year ~10K new food products a year ~9/10 fail

Tech Spectrometers Gas chromatographs Vapor detectors Can discern chemicals at 1 ppb Human nose can tell % Dogs better still

Complex flavors Coffee, roast beast, strawberries; thousands of chemicals at once Chemical responsible for flavor of Bell pepper only need 0.02 ppb: a drop could flavor a swimming pool And its cheap: flavor in 12oz of Coke = ½ cent

Often though, 1 chemical provides the over-riding sense of the food. Ethyl-2-methyl butyrate = apple Methyl-2-peridylketone = popcorn Ethyl-3-hydroxybutanoate = marshmallow Hexanal = fresh cut grass 3-methyl butanoic acid = B.O.

So what? So natural flavor means its made using old technology Natural Getting amyl acetate from distilling bananas with a solvent Artificial Getting amyl acetate from mixing vinegar with amyl alcohol, adding H 2 SO 4 as a catalyst Both taste exactly the same, both happen in the same factory, but people want to see natural on their label.

Art or Science? Mouthfeel: Its not just flavor, TA.XT2i Texture analyzer uses 250 probes to create an artificial mouth that senses bounce, creep, crunch, density, chewiness, gumminess, lumpiness, rubberiness, slipperiness, softness, wetness, spread, spring- back, tackiness How do you juggle all of this with subtleties of flavor?

Genetics Dominant gene Phenylthiocarbamide, also known as PTC, or phenylthiourea tastes very bitter or not at all depending on genetics Discovered when a guy at duPont accidently spilled a bunch of crystalline PTC, some complained, some did not May explain why some people are more offended by cig. smoke

Super Taster ~25% of people of European dissent Maybe more fungiform papillae Linked to food preference, body type Coffee, alcohol, may be too intense Olives too salty

Things go horribly awry Ageusia (pronounced ay-GOO-see-uh) Loss of sense of taste –From neural damage anosmia - a loss of the sense of smell. –Cold –Parkinson’s –Alzheimer's