Evolutionary Trends in Skulls- Cerebral Cortex, Dentition (18) Flashcards
What portion of the brain shows the greatest degree of development
- Outer portion of cerebrum= cerebral cortex
Where is the largest enlargement of surface area of the brain and what does this area control
o Compared with apes, frontal lobe= largest enlargement of surface area
o = higher functions of thinking, reasoning, planning, processing
♣ In humans= 47% of total cortical surface
♣ In apes= 33%
What did larger brains require anatomically
o In humans more of skull used in housing brain than in apes
♣ Consequence= the brow tends to be vertical and lacks prominent brow ridges possessed by apes
why are humans noses prominent
o less brow + more forhead + shortening of snout, = given human flatter face
♣ Although bones in nose still protrude
• For this reason, humans have far more prominent nose than any other primate
what occurred first, bipedalism or brain increase size
bipedal locomotion
what is an endocast
impressions of inside of skull made from rock or some other solid material)
What else, besides increase in cranial capacity, do endocasts show
o Gradual increase in number of convolutions and size of frontal lobe evident
o Trends seen in homo erectus fossils
♣ Over time species lived increase from 750cm3 to 1250 cm3
♣ As brain expanded, face tended to become flatter and noticeable forehead began to develop in later members of species
• Probably due to expanding frontal lobe
What is change in canine teeth in humans
o Canine teeth do not project beyond level of other teeth and interlock (like in Old World)
♣ Look more like incisors
What has small canines and relativly small incisors resulted in
o take up less room in jaw
♣ // shape of tooth row (dental arcade) evolved into different shape
what are the dental arcade shape of humans and apes
• instead of U pattern in apes, become more parabolic
Were afarensis teeth similar to apes and how
o lower jaw and face that was more like ape
♣ Teeth were large, and as in apes distinct gap between canines and incisors, with rows of teeth parallel rather than curved
where canines still prominent in homo habilis
yes
