All early hominids (from 2 million to 30,000 years ago) and modern Homo sapiens, until 15,000 years ago, lived as hunters and
gatherers. We took our food directly from the environment. We dug roots, picked berries and killed animals and fish.  Note that it would be nearly impossible to live as a hunter - gatherer today. In fact, it is illegal to hunt and gather on public lands except during special hunting periods.

Size and density of Hunting and Gathering societies were small by today's standards. They usually consisted of fewer than 40 people. There were thousands of these societies scattered about the planet. Population densities were about 0.6 persons per square mile. A hunting and gathering society needed several hundred square miles of territory as they were constantly on the move looking for new food supplies. They had no permanent settlements.

Social Institutions were fewer and primitive by today's standards.

    The Family is the major if not only institution. Most societies allowed divorce and it appears to have been very common in some. Infanticide (15 to 50% of all live births) and abortion appear to have been common.
    The Economy was primitive. Males were hunters; females were gathers. Except in Arctic, gathering (women) provided 60 to 80% of food supply. Except were the climate is extreme, hunters and gatherers are thought to have worked about 15 hours per week.
    Religion was based on animism, the belief that spirits inhabit virtually everything in the world.
    Politics was somewhat democratic with decisions reached through discussion and consensus. Some did have a chief or headman but their power was limited.
    Education was informal. There were initiations into various stages of life (e.g., birth, puberty, marriage, death).
    Art and leisure consisted of music, dancing and storytelling. Games were based on physical skill and chance. There are no records of these societies having games of strategy.
    Warfare existed but was rare and ritualistic. There was little to fight over.

Stratification was minimal. Private ownership of land was virtually absent. With constant moving it was difficult to anyone to accumulate much wealth.

External links about hunters and gatherers

    Paleolithic 40,000 to 12,000 BCE
    Neolithic 12,000 BCE
    The Aboriginal and Torres Strait Islander
    Navajo Silver
    The History of India
    The Fremont (Utah)
    Cherokee History

For further reading I suggest: Human Societies: An Introduction to Macro sociology by Gerhard Lenski, Jean Lenski and Patrick Nolan. McGraw-Hill, Inc.