looks at the human distinct physical features which might have been able to support speech production
• the crucial observation that human ancestors made a significant transition to an upright posture, with a bi-pedal (on two feet) locomotion
• some effects of this change can be seen in differences between the skull of a gorilla and that of a Neanderthal man from around 60, 000 years ago
• moreover, there are certain human physical features, considered partial adaptations, which are relevant for speech