The document discusses two competing theories for the evolution of the long neck in giraffes - the traditional theory that giraffes evolved longer necks to reach higher foliage during times of scarcity, and the alternative theory proposed in 1996 that neck length increased due to sexual selection for combat between males using their necks as weapons to compete for mates. Evidence for both theories is presented, with the sexual selection theory noting that only male giraffes engage in necking behavior and it can result in unconsciousness or death for weaker males.