Data on susceptibility to motion sickness were collected on a sample of 535 individuals divided into eight groups. The prevalence of motion sickness among Tibetans and Northeast Indians (28%) was slightly higher than Northwest Indians (26%). Generally speaking, females (27.3%) were more susceptible than males (16.8%). Among different groups, the highest incidence of susceptibility to motion sickness (SMS) was recorded in schizophrenic patients (30%), while the lowest in rowers (zero percent). Ears and eyes are the most potent receptors of provocative motion that causes sickness. Individuals with greater spatial and motor control, reflected in sports like rowing, athletics and professions like armed and paramilitary forces, were less susceptible to motion sickness.

The SMS was significantly higher in individuals who suffered from spatial disorientation (35.05%), migraine (26.31%), gastrointestinal disorders (26.82%) and those who were more sensitive to unpleasant odours (24.64%) and preferred sweet flavours (24.48%) than their counterparts. These correlates have been utilized to explain the genesis of sickness using threshold model. Genetic and environmental pathways are strongly advocated. Past episodes of motion sickness acted as a strong psychological attribute in determining further episodes. The roadway buses and trucks proved more effective passive transportation types that caused sickness. The voluntary stabilization of the head and neck movements and gaze control proved very effective natural measures adopted by 38% subjects to avoid or limit motion sickness. About 50% of susceptible individuals became less susceptible or fully acclimatized to motion sickness due to habituation. The mean age at acclimatization was 21.98 ± 5.93 years.

Malawi is a country in South-East Africa with a population of approximately 10 million, over 95% of whom are negro of Bantu origin. The country is divided into 24 administrative districts, each of which provides details of births which are compiled centrally at the Ministry of Health. Using data reported annually by health facilities from 1987-1990, most districts had twinning rates in the range 16 to 24 per 1000 maternities, figures consistent with those of other negro populations in Africa. Two adjoining districts (Rumphi and Mzimba) had rates which were considerably higher, almost 30 per 1000. Although ethnic origin is not recorded in the latest Malawi census, language spoken in the home, which was last recorded in 1966, can be used as a proxy. Rumphi and Mzimba are the only districts with an overwhelming majority of Tumbuka speaking population. These people, who are of both Tumbuka and Ngoni ethnic origin, therefore have an unusually high twinning rate (29.57 per 1000 maternities). The rate for the main ethnic group in Malawi, the Chewa people, was 21.21 per 1000. The district of Thyolo, with a mixed ethnic population, had by far the lowest rate (13.75 per 1000).