Biosocial domain is physical changes in human development, in infant the start experiencing normal body functional right from birth this follow by certain changes in behaviour for instance like sucking, arm stretching and embracing of mother for protection from strangers and any danger. They continue to develop some ongoing reflexes throughout their lifetime example like bleaking, breathing, yawning and swallowing.
Infants spend alot of time sleeping an average of 16-21 hours a day and their sleeping hours reduce as they grow older (Michelsson, Rinne,&Paajanen, 1990; Peirano, Algarin,& Uauy,2003; Buysse, 2005) ). Majority start seeing and hearing right from birth but their over roll vision improves from age one month (Seidel, Rosenstein, & Pathak, 1997). ), they prefer human faces compare to others stimuli ( Dannemiller & Stephens, 1988). ).
At age three months they can differentiate human faces (Morton, 1993). Infant can distinguish different sound right from early age for instance positive and negative(emotional) sound, loud and soft voices( ), at four to five months infants may prefer or like the sound of musical instrument, (Krumhansl & Jusczyk, 1990,). Infant experience different stages of movement until they put their first step, they start by crawling, standing and stepping then finally walking (Thelen, 1989).
Reaching and grasping develop from four to five months of age (Pownall&Kingerlee, 1993; Von Hafsten, 2004). Among some African culture, adult but pressure on infants to walk right from early stages. (LeVine, 1994; Munroe, Munroe, &Whiting, 1981) same thing among the Australian native they coach infant to walk at early stages unlike the Anglo Australian(Kearine, 1986). Infant’s development both in developing and developed world are affected by low-birth-weight, mortality, malnutrition, poor nutrition and over nutrition.
In previous studies by UNICEF showed that India has the highest percentage of low-birth-weight babies at 30 per cent compare to Australia and New Zealand which had 6-7 per cent. (UNICEF,2008B). High mortality rate, poor nutrition and malnutrition are the key factors that affect infants growth or development in developing countries especially Africa where as Western world infants suffer from over nutrition for instance it was found that infant consume 20 per cent more calories than they need(Briefel, Reidy, Karwa, Devaney, 2004).