APES VS. HOMININ BRAINS & BEHAVIOUR

=Non-skeletal Differences between Apes and Hominins= [image:http://i.imgur.com/TuWc6Ez.png?1] '''Brain''' Humans have a larger brain (relative to their overall size) than any other mammal. The greatest difference or area of enlargement is in the '''grey matter''' of the '''cerebral cortex''' (outer layer). This region of the brain is folded many times to increase its surface area and plays a key role in memory, attention, motor instructions, perceptual awareness, thought, language, and consciousness (complex mental processes). '''Skin''' Humans don’t actually have fewer hairs but finer, shorter hairs. We also have a far greater number of sweat glands that can produce up to 12L of sweat per hour! This would have given our ancestors the ability to maintain high activity under the tropical sun. '''Speech''' Humans are the only animals that can communicate by spoken language. After bipedal walking the development of speech was probably the most significant advance in human evolution because it enabled complex ideas to be communicated quickly. The initial production of the sound occurs in the larynx (voice box), however, the wall of the pharynx contains muscles that permit the sound to be modified, producing vowel sounds such as ‘ee’, ‘ahh’, ‘oo’. [image:http://i.imgur.com/AXrQPJ8.png?2] In great apes the pharynx is much shorter than in humans and cannot make the full range of vowel sounds. The hominin brain also developed two areas dedicated to the Interpretation of phonetic sequences ('''Wernicke’s area''') and the organisation of sounds into meaningful sequences ('''Broca’s area'''). [image:http://i.imgur.com/nCvSd8g.png?2] '''Parental Care''': Apes take care of their young for much longer than other species, whose young are often relatively independent shortly after birth. The period of juvenile dependence is even greater in humans because we have a narrower pelvis that would not accommodate our enlarged brain / skull during childbirth if it were fully developed. This is why a modern human baby continues much of its development outside the womb. Early development focuses on the growth of the brain and learning in the protective environment of the family group. This means that greater parental care is required for a longer period, but it also provides the opportunity for a longer period of learning. This may also explain why humans, unlike other animals, have a life expectancy that extends well beyond their reproductive years (grandparents can help during this period of dependancy).