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1. What are the main changes in the characteristics of the skull during hominization? Which characters should be considered ancestral and which derived? · Bipedalism: The foramen magnum goes forward (to the anterior part of the skull) to make humans being able to walk in just two legs. · Brain size (expansion of cranial capacity): The brain have been getting bigger throughout hominization and that’s because of the use of fire and the trade-off between the gut and the brain; men had “healthier” food because it was cooked and they didn’t need a strong digestive system as well as they could cook meat which have a high amount of calories.

· Jaw: It gets less prominent. · Teeth: They get smaller. It was caused because of the change of the diet from vegetarian to omnivore. Since ancestral and derived characters are relative to the homo we are talking about, I will take the Homo sapiens as the “youngest” and the A. Africanus as the “oldest”. Derived characters: Bigger brain capacity, forehead and chin. Ancestral characters: Foramen magnum (although the position changes). 2. What is the function of the sagittal crest? The muscles that assist the closing of the jaws are attached there. It’s typical of mammals and reptilians that have a powerful biting. 3. Why did the canines tend to decrease? As well as the jaw decreased, the canines did the same, and this was because of the change on diet (from herbivore to omnivore). 4. Why did the face tend to get flat? The evolution of an orthognathic face in humans is related to the reduction of teeth’s size, chewing muscles and jaw. 5. Which parts of the skull did increase in size first? In the hominization process, we can observe an increase of the neurocranium (anterior part of skull) whereas the splanchnocranium (face) is reduced. The canines do also get reduced. 6. Have the brow ridges disappeared in modern humans? The brow ridges are not very prominent in modern humans. 7. What are the implications of the increase of the anterior part of the skull with regards to brain mass? Which brain areas are located in this part of the skull? The increase of the anterior part is related to the growth and development of the frontal lobe of the brain, located at this area inside the skull. 8. What cognitive processes are located in that area of the brain? The frontal lobe is involved in higher mental functions such as creative thinking, planning of future actions, making decisions, emotions, as well as working memory, language and motor control. Therefore we can conclude that much of the behavior along the hominization process like the creation of tools in homo habilis or the use of language are due to the growth of this brain area.

9. What is the relation between the position/orientation of the foragmen magnum, the posture, and the locomotion? In bipedal hominids, the anterior position of the foramen magnum helps to balance the mass of the head above the vertebrae and its inferior orientation reflects the anatomical relationship between the cranium and vertebral column. Also the anterior position let humans walk on two legs.