Taste worlds of humans vary because of taste blindness to phenylthioca
rbamide (PTC) and its chemical relative, 6-n-propylthiouracil (PROP).
We review early PTC studies and apply modern statistical analyses to s
how that a higher frequency of women tasted PTC crystals, and were tas
ters (threshold classification). In our laboratory, scaling of PROP bi
tterness led to the identification of a subset of tasters (supertaster
s) who rate PROP as intensely bitter Supertasters also perceive strong
er tastes from a variety of bitter and sweet substances, and perceive
more burn from oral irritants (alcohol and capsaicin). The density of
taste receptors on the anterior tongue (fungiform papillae, taste buds
) correlate significantly with perceived bitterness of PROP and suppor
t the supertaster concept. Psychophysical data from studies in our lab
oratory also show a sex effect; women are supertasters more frequently
. The anatomical data also support the sex difference; women have more
fungiform papillae and more taste buds. Future investigations of PTC/
PROP tasting and food behaviors should include scaling identify supert
asters and separate sex effects.