| Chapter 2: | Humans |
*Other pre-Homo and Homo species are not included in this list.
Sources. Goodman et al., 1998, 2005; National Geographic, February 1997, July 2010; Pickering et al., 2011; Pollard, 2009; Stauffer, Walker, et al., 2001; Tattersall & Mearns, 2000; White et al., 2009.
Humans are unique. They are apes but not chimpanzees. Little can be learned about human behavior from the study of chimpanzees. To understand human beings, one must go further back, to the ancestor of all apes, including the gibbons, so-called lesser apes. All apes lack tails, have mobile shoulders, and can stand erect. Climbing and feeding in an upright posture (sitting or hanging) and walking along branches using long arms for support define the ancestral locomotion common to all apes (Chivers, 1984). An interesting feature shared among all hominoids (apes and humans), but absent in monkeys and other primates, is a ligament in the shoulder, the coraco-acromial ligament, and associated projections of the shoulder joint, that permits unique locomotor and feeding motions (Ciochon & Corruccini, 1977). This shoulder flexibility combined with leverage and power allows a chimpanzee to swing a stick over its head in a threat display, and a quarterback to accurately throw a football into the end zone from midfield.