Complex sentence: Milligan-Whyte asserts that mankind has no future in clash of civilization because of the power of 21st century weapons, technology and science and that collaboration of civilizations is essential if mankind is to prevent its extinction as a living gene pool.
Split into simpler sentences: Milligan-Whyte asserts that mankind has no future in clash of civilization because of the power of 21st century weapons, technology and science. Therefore the collaboration of civilizations is essential if mankind is to prevent its extinction as a living gene pool.