Related Clues:

• Steps in human evolution
• Earth rulers in a 1968 film
• Extras in the opening of '2001: A Space Odyssey'
• Monkeys' uncles?
• Bronx Zoo houseful
• Siamangs, e.g.
• Gorillas and chimps
• Real swingers?
• 'Great' beasts
• Follows suit
• 8-Down and others
• Zoo houseful
• Big galoots
• Forest swingers
• Kong and Young