With 250 million competitors, it is the most extreme race on earth and there can only be one winner.With 250 million competitors, it is the most extreme race on earth and there can only be one winner.With 250 million competitors, it is the most extreme race on earth and there can only be one winner.
Allan Pacey
- Self - Sperm Expert: University of Sheffield
- (as Dr Allan Pacey)
Chris De Jonge
- Self - Fertility Expert: University of Minnesota
- (as Dr Chris De Jonge)
Joanna Ellington
- Self - Sperm Physiologist
- (as Dr Joanna Ellington)
Geoffrey Miller
- Self - Evolutionary Psysiologist: University of New Mexico
- (as Dr Geoffrey Miller)
Alex Travis
- Self - Reproductive Biologist: Cornell University
- (as Dr Alex Travis)
Curtis Cripps
- Sperm
- (uncredited)
Raymond G. Rempel
- An 'Athletic' Sperm
- (uncredited)
Mara Stevens
- Sperm
- (uncredited)
Gill Stoker
- Sperm
- (uncredited)
