5. Supertasters

People who experience taste with greater intensity than the rest of the population are called supertasters. Having extra fungiform papillae (the mushroom shaped bumps on the tongue that are covered in taste buds) is thought to be the reason why these people have a stronger response to the sensation of taste. Of the five types of taste, sweet, salty, bitter, sour, and umami, a supertaster generally finds bitterness to be the most perceptible.

Scientists first noticed the differing abilities of people to taste a known compound when a DuPont chemist called Arthur Fox asked people to taste Phenylthiocarbamide (PTC). Some people could taste its bitterness; some couldn’t - whether people could depended on their genetic make-up (a variant of this test is now one of the most common genetic tests on humans). While about 70% of people can taste PTC, two thirds of them are rated as medium and only one third (approximately 25% of the wider population) are supertasters.

4. Absolute pitch

People with absolute pitch are capable of identifying and reproducing a tone without needing a known reference. It is not simply a better ability to hear but the ability to mentally class sounds into remembered categories. Examples of this include identifying the pitch of everyday noises (e.g. horns, sirens, and engines), being able to sing a named note without hearing a reference, naming the tones of a chord, or naming the key signature of a song.

Estimates of the portion of the population having absolute pitch range from 3% of the general population in the US and Europe to 8% of those (from the same areas) who are semi-professional or professional musicians. In music conservatories in Japan however, about 70% of musicians have absolute pitch. Part of the reason for this significantly larger percentage may be because absolute pitch is more common among people who grew up in a tonal (Mandarin, Cantonese, and Vietnamese) or pitch accent (Japanese) language environment.

3. Tetrachromacy

Tetrachromacy is the ability to see light from four distinct sources. An example of this in the animal kingdom is the zebrafish (Danio rerio), which can see light from the red, green, blue, and ultraviolet sections of the light spectrum. True tetrachromacy in humans is much rarer however according to Wikipedia only two possible tetrachromats have been identified.

Humans are normally trichromats, having three types of cone cells that receive light from either the red, green, or blue part of the light spectrum. Each cone can pick up about 100 graduations of color and the brain combines colors and graduations so that there are about 1 million distinguishable hues coloring your world. A true tetrachromat with an extra type of cone between red and green (in the orange range) would, theoretically, be able to perceive 100 million colors.

2. Genetic Chimerism

In the Iliad Homer described a creature having body parts from different animals, a chimera, from this mythological monster comes the name of the genetic equivalent chimerism. Genetic chimerism, or tetragametism, in humans and other animals happens when two fertilized eggs or embryos fuse together early in pregnancy. Each zygote carries a copy of its parents DNA and thus a distinct genetic profile. When these merge, each population of cells retains its genetic character and the resulting embryo becomes a mixture of both. Essentially, a human chimera is their own twin.

Chimerism in humans is very rare; Wikipedia states that there are only about 40 reported cases. DNA testing is often used to establish whether a person is biologically related to their parents or children and can uncover cases of chimerism when DNA results show that children are not biologically related to their mothers - because the child inherited a different DNA profile to the one shown by a blood test. This is what happened in the case of Lydia Fairchild: DNA tests of herself and her children led the state to think that she was not actually their mother.

1. Synesthesia

Imagine consistently associating numbers or letters with certain colours, or hearing a specific word which triggers a partic ular sensation of taste on your tongue. These are two forms of a neurological condition called synesthesia. Synesthesia is when stimulation of a particular sensory or cognitive pathway leads to an involuntary (i.e. synesthesia is not learnt) response in other sensory or cognitive pathways.

Synesthesia is most often genetic and the grapheme (letters, numbers, or other symbols) to colour form of synesthesia is the commonest. Other synesthetes can experience special-sequence synesthesia (e.g. where dates have a precise location in space), ordinal linguistic personification (when numbers have personalities), or sound to colour synesthesia (where tones are perceived as colours).

Although synesthesia is a neurological condition it shouldn’t be thought of as a disorder, because generally it does not interfere with a person’s ability to function. Most people are not even aware that their experiences of life elicit more sensory responses than other peoples might and the ones that are rarely consider synesthesia to have a negative impact on their lives.

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