Code Talker, born sometime during the late 19th Century, was an elderly man who Big Boss encountered during the 1980s.
Code Talker features in the E3 2013 trailer for The Phantom Pain, with the subtext of "A Wise Man denied his homeland."
The original Wisemen's Committee was a secret group of the most wealthy and powerful minds from the United States, Russia (Soviet Union at the time) and China who formed the Philosophers after the first World War.
Code Talker could be one of the Wisemen's Committee; a chairman of the group from Russia. Forming the Philosophers resulted in the deaths of the Wisemen's Committee throughout the Great Depression in the 1930s. Under threat of death from the Philosophers, Code Talker goes into hiding to avoid assassination. By the time he comes out of hiding, he is a decrepit old man, approximately 100 years old by the time of The Phantom Pain.
And Big Boss meets him; one of the original Wisemen. The only surviving member of the Wisemen's Committee, as far as we know.