Evidence for genetic determination in human twins of olfactory thresholds for a standard odorant.

Olfactory thresholds for four odorants were determined in groups of monozygotic and dizygotic human twins. Odorants were presented in an ascending dilution series in odorless solvent, using a three-way forced choice method. For two of the tested odorants, 5 alpha-androst-16-en-3-one and isoamyl acetate, the thresholds showed a strong genetic component.

Behavioral reactions to gustatory stimuli in young chicks (Gallus gallus domesticus).

Freely-moving, posthatch chicks were individually presented 2 concentrations each of quinine, citric acid, fructose, sucrose, sodium saccharin, and distilled water and their behavioral reactions were videotaped and analyzed. Already during the first posthatch day distinct rejection responses to quinine and citric acid could be recognized. Prolonged head shaking and beak clapping episodes were the most dominant features of these reactions.