delinquent noun [C]. âº a âperson, usually âyoung, who âbehaves in a way that is âillegal or not âacceptable to most âpeople: âjuvenile delinquents.
Sahelanthropus may have walked on two legs. The oldest evidence for walking on two legs comes from one of the earliest humans known, Sahelanthropus. Walking upright may have helped this species survive in the diverse habitats near where it livedâincluding forests and grasslands.
Scientists claim that walking on two legs was one of the keys to humans' development from ancient ape-like ancestors. Walking on two legs saved energy and allowed the arms to be used for activities like hunting, crafting simple tools and interacting with objects. Charles Darwin proposed long ago that having two limbs free to use tools constituted a key element of advanced intelligence [source: National Geographic].