The discovery and use of fire was very important to early man for several
  They discovered that most animals are afraid of fire. So a campfire gave
  some protection to the group or tribe.
  They could camp in better locations. The fire, which gave them protection,
  allowed them to choose places for camping. They no longer had to look
  for trees to climb into or rocks and cliffs to shelter under.
  It kept them warm. This goes with the second reason. They could move
  into colder climates and hunt the animals that lived there. They could then
  return to their campfire to warm up.
  It was a healthier way of life. Cooked food is less likely to carry disease.
  People began to cook their food consistently. As a result, it would have
  been easier for the young and the old to survive.
  It was a more social grouping. They could now gather in larger groups,
  feeling safer and more secure. This allowed them to exchange stories, and
  just talk to other people.
What went on earlier and later is, of course, still unknown. By the time we
reach the upper Paleolithic stage, their occurrences become more profuse and
the tools more diverse and beautiful.
Distribution and Characteristics of Mesolithic Cultures
Transition between Pleistocene and Holocene Periods Towards the end of
the geological period of Pleistocene (Ice Age) and the beginning of the
geologically Holocene (Recent, Ice-free Age) period, and between the
hunting-gathering upper Paleolithic and the Neolithic or a universal stage
indicating the beginning of food-production and village-farming economy,
the place of the Mesolithic as a distinct archeological level has been well
acknowledged in archeology. In the Indian situation, on the one hand, we
would assign this level to the preceding upper Paleolithic, and on the other, it
should be earlier than the first manifestation of the village-farming economy
in the regional context. Correspondingly, it should also be possible to ascribe
it to a geological context of the late Pleistocene-early Holocene phase.