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77 votes
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Is there an RGB equivalent for smells?

There are about 100 (Purves, 2001) to 400 (Zozulya et al., 2001) functional olfactory receptors in man. While the total tally of olfactory receptor genes exceeds 1000, more than half of them are ...
AliceD's user avatar
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43 votes
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Are drugs made bitter artificially to prevent being mistaken for candy?

Short answer A bittering agent may be applied to therapeuticals to prevent pediatric poisonings, but many drugs inherently taste bitter by themselves. Background Bitter taste is thought to have ...
AliceD's user avatar
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35 votes
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Why does my room suddenly look 'reddish'? My eyes seem to adapt to color

Short answer The phenomenon you describe can be explained by the negative afterimage effect, which indeed is elicited by adaptive processes in the retinae. Background In the retina there are three ...
AliceD's user avatar
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35 votes
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Did predators evolve eyes first?

Short answer Complex eyes may have evolved first in predator species, specifically in box jellyfish. Trilobites are another group of animals where complex eyes may have evolved first. The trilobites ...
AliceD's user avatar
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33 votes
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Can one see flickering of a light bulb at 50 Hz?

Short answer Yes, the flickering of a light bulb may be noticeable, and yes, that's directly related to the mains frequency. However, since the flickering of a bulb is about two times higher than the ...
AliceD's user avatar
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27 votes
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Why is loud music much louder after pausing and resuming it?

Hearing is capable of sensory adaptation such that prolonged constant stimulus is perceived as less intense. In hearing, the adaptation to loud sounds is called acoustic reflex and is mediated by two ...
Domen's user avatar
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20 votes

Did predators evolve eyes first?

AliceD's answer is great but just to address your points 1 and 2. Eyes are expensive. From a study on fish loosing their vision in caves. The cost of vision was calculated to be 15% of resting ...
Sam Dean's user avatar
  • 301
13 votes

Did predators evolve eyes first?

Eyes evolved multiple independent times in convergent evolution. Almost all the vertebrates have eyes. Those few that doesn't lost their eyes through evolution and live in deep ocean of in caves where ...
Victor Stafusa - BozoNaCadeia's user avatar
12 votes

Why do I still see a bright light after looking directly at it?

Short answer The effect you describe is called a negative after image. It can be explained by adaptation effects of the photoreceptors in the eye. Background source: Dresden University Steadily ...
AliceD's user avatar
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10 votes
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What is the smallest touch sensation that a human can feel?

Short answer The detection threshold of static indentation stimuli on the palm of the hand is approximately 10 to 40 micrometers, dependent on the exact location under investigation. Background The ...
AliceD's user avatar
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9 votes

Is there an RGB equivalent for smells?

There are many, many more parameters than 200! As an example, look at the nomenclature system for olfactory receptors (ORnXm). "OR" is the root name (Olfactory Receptor superfamily) n = an integer ...
Drunken Code Monkey's user avatar
9 votes
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Can a color-blind person see color with filter glasses?

Short answer Optical filters can optimize color contrast, but never restore color blindness. Filters remove colors, they can never add something. However, glasses like this can prove helpful for ...
AliceD's user avatar
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8 votes
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Can frogs see clearly under and above water?

Short answer Frogs are nearsighted on land and farsighted under water. Background Frogs are reported to be nearsighted on land, but farsighted underwater (source: Chegg Study). Nearsightedness (...
AliceD's user avatar
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8 votes

Can one see flickering of a light bulb at 50 Hz?

A lamp flickers at 2x the mains frequency, i.e. 100 or 120 Hz, and that is typically not noticeable to human eyes. It is visible to chicken and insects. That being said, a low quality lamp or a lamp ...
StessenJ's user avatar
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7 votes
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Why do humans not have a powerful sense of smell?

Humans' poor sense of smell is a myth, borne of 19th century speculation rather than actual data. This is described in an excellent recent paper in Science , "Poor human olfaction is a 19th-century ...
Raghu Parthasarathy's user avatar
7 votes

Why do humans not have a powerful sense of smell?

There are several factors in human. we are upright, which brings the nose just about as far away for scents as it can get, you want your nose as close to the ground as possible for the most efficient ...
John's user avatar
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7 votes
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What would happen if you "rewired" your eyes with your nose?

"Rewiring" the brain isn't quite that simple: simply splicing a nerve to another doesn't necessarily mean the axons of that nerve will then grow into area. I am unaware of any studies that cross these ...
Bryan Krause's user avatar
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6 votes

How statistically significant was the "sweaty T-shirt" experiment?

@bshane has already provided an excellent answer to the question. However, I just found a recent review published in Molecular Ecology (Winternitz et al., 2016) in which the authors performed a ...
AlexDeLarge's user avatar
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6 votes
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What causes the tonotopic organization of the inner ear?

The frequency tuning in the cochlea is due to a number of factors. The primary factors of cochlear frequency tuning are generally ascribed to the passive physical characteristics of the basilar ...
AliceD's user avatar
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6 votes
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Why is peripheral vision not bleached by daylight?

Short answer In photopic lighting, peripheral vision is mediated by cones. Background The rods are indeed saturated at daylight, and even at twilight (source: Nature). However, the cones are active ...
AliceD's user avatar
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5 votes
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Are resonances the reason receptors work?

Photoreceptors themselves dont act as oscilators, a single receptor is either 'on' or 'off' - it does not respond differently to different wavelenghts. Humans have Trichromatic vision, which means ...
Nicolai's user avatar
  • 4,391
5 votes

Understanding the "Waterfall Illusion"

The motion after-effect (MAE) is believed to be primarily due to adaptation of direction sensitive cells in the middle temporal area (MT) (Fig. 1.). The directional cells in this area of the cortex ...
AliceD's user avatar
  • 52.5k
4 votes

How can bobcats feel the mice under the snow?

You can smell roughly where your pan is cooking, but you can hear it with more precision, in order to pin point something you would tend to use your ears, especially if it is under snow. Cats use all ...
bandybabboon's user avatar
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4 votes
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What causes Pseudomonas fragi to smell sweet?

The strawberry-like odour that you perceived is mainly attributed to three ethyl esters, namely the ethyl esters of butyric, hexanoic and 3-methylbutanoic acid. There are other odour-active volatiles ...
Johnny's user avatar
  • 1,509
4 votes
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Why do coliform bacteria smell so bad?

E. coli and other bacteria metabolize tryptophan into odoriferous skatole and other indole compounds. If you're culturing these organisms in medium that contains tryptophan, that may be what you're ...
Alex Reynolds's user avatar
3 votes

Is there an RGB equivalent for smells?

Yes, it certainly is. But I cannot guarantee that all have been properly determined. For that, we would have to find the basic unique values (like the Red, Green and Blue in the case of colors). ...
Overmind's user avatar
  • 131
3 votes

What is mold detection threshold in humans?

It depends on the mold. For example, humans can smell octenol in ppb concentrations[1], presumably long before any toxic effects of this or other compounds produced by molds. Octenol is produced by ...
R Stephan's user avatar
  • 3,850
3 votes

Nature of sight/ color perception?

The color you perceive is ultimately dependent on the relative contributions of the color photoreceptors in the retina, namely the red, green and blue cones. The sensation of color, therefore, is ...
AliceD's user avatar
  • 52.5k
3 votes

What causes the tonotopic organization of the inner ear?

To add to Christiaan's answer, the length of the hair cells also changes along the basilar membrane. They are longer and floppier near the apex. There are many levels of mechanical interaction ...
Bzrs's user avatar
  • 223
3 votes

Do ants use something similar to the honey bee "waggle dance" to instruct the rest of the colony where to find a food source?

I can only help you on one question about if ants perform a similar communication such as the "waggle-dance" to tell other ants if there is food elsewhere? Ants will send out scout ants or forages, ...
Jack Bug Boy Weatherington's user avatar

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