In 1963 he produced a book summarising the evidence the Commission had received, studies from other parts of the world, and further evidence from history. He built up on this basis a consistent picture of the creature and discussed its possible relation to Neanderthal man. The book was never actually completed, but 180 copies of a preliminary version were circulated to colleagues in Moscow. The book then disappeared for well over half a century. With the assistance of Porshnev’s family the manuscript has now reached the West and is published here in an English translation with the addition of notes, maps, illustrations and an index. This book casts a wholly new light on the Yeti, Bigfoot and the possible survival of human ancestors into the present day.