The aim of this work was to study taste sensitivity to phenylthiocarbamide (PTC) amongst Bedouin tribes and compare the Bedouins with Arab and Jewish populations. Data obtained by the classic method of serial dilutions in 317 healthy male Bedouins, aged 16–70 belonging to different tribes, were examined. We discovered significant differ­ences in chemosensitivity to PTC in the Bedouin communities. A high frequency of the t allele was documented in the Bedouin tribes of Hamada, Muzeina, and

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... Bedouins" and a relatively low level of the t allele frequency in the Gebelia tribe. The frequencies of non-tasters amongst Arab groups were similar in values to those of the Gebelia tribe. Three other Bedouin tribes showed very high values for the non-tasters' frequencies. The revealed intertribal differ­ences can be explained by the genetic drift in isolated populations, on the other hand, this may be the result of endog­amy.