Abstract

The indigenous populations Orang Asli (OA) of Peninsular Malaysia are divided into three major communities or tribes, namely the Negrito, Senoi and Proto-Malay. These tribes can be further divided into further sub-tribes based on unique linguistic, morphological and cultural characteristics. Many of these communities live in rural and forest fringes whilst the rest live in urban areas. Despite modernization, some groups such as Mah Meri, Temiar and Jakun still observe unique cultural practices including rituals music, dance, animism, herbalism and spiritual rituals. Previously, hunter gathering, fishing and swiddening were main activities but rapid development in recent years have caused many changes. Throughout the centuries, numerous anthropological and linguistic investigations have informed our knowledge about these populations but genetic histories of these populations remained obscure. We investigated the genomics of these 3 major groups and discovered that although all OA groups are genetically closest to East Asian (EA) populations, they are substantially distinct. Evidence indicates that these peoples are the descendants of the earliest human migrations out of Africa into South East Asia. Genetic affinity between Andamanese and Malaysian Negritos suggest an ancient link. Formal admixture tests provided evidence of gene flow between Austro-Asiatic speaking OAs and populations from South East Asia and South China suggesting a widespread presence of these people in SEA before the Austronesian expansion. Estimates indicate OAs diverged from East Asians probably during the late Pleistocene (14.5 to 8 YBP ). The continuum in divergence time from Negritos to Senoi and Proto-Malay in combination with ancestral markers provides evidences of multiple waves of migration into SEA starting with the first Out-of-Africa dispersals followed by Early-train and subsequent Austronesian expansions. We also investigated the effects of socio-demographic change and urbanization on the cardio-metabolic risks and found variable prevalence of obesity, cholesterol, hypertension and diabetes in various tribes.