1st of all livelihood is a means of supporting one's existence, esp. financially or vocationally; living.
there r various sources of livelihood-- Hunting, fishing and gathering were the only means to survive during prehistoric times in harsh conditions. The life of hunter-gatherers followed a rhythmic, annual cycle. They followed the regular events of nature and moved after the game and good fishing places. Cultural features of these small societies have been impacted by the most dominant source of livelihood.