All evolutionary changes that allow a species to change in response to the environment, are originally a result of

...are originally a result of eukaryotes evolving from prokaryotic ancestors and met a very important increase of complexity.

The truman doctrine was an american foreign policy whose stated purpose was to counter soviet geopolitical expansion during the cold war. it was announced to congress by president harry s. truman on march 12, 1947, and further developed on july 12, 1948, when he pledged to contain threats to greece and turkey