Lamarck was the french naturalist. He proposed that acquired characters are inherited from one generation to another.
Oparin belonged to Russia and proposed that the first form of life could have come from pre-existing non-living organic molecules (e.g. RNA, protein, etc.) and that formation of life was preceded by chemical evolution.
S.L. miller an American scientist proposed the chemical evolution of life.
Thomas malthus was from England and worked on populations. He proposed that population growth will always tend to outrun the food supply and that betterment of humankind is impossible without strict limits on reproduction.