Anthro2050 1st Edition Lecture 24 Outline of Last Lecture I Sites and Geology Continued II Humans and Apes Outline of Current Lecture II Humans and Apes Cont Current Lecture Humans and Apes Cont Chins Apes and early humans had no chins it started appearing closer to modern humans Human chins have a thicker enamel than apes without chins most changes in body below cranium are due to bipedalism major shift in centre of gravity for balance vertebral column curvature made so the spine better supports un upright body thorax shape apes funnel shaped narrow at the top then spread out at the bottom bipedal hominids barrel shape narrow at top and bottom to give extra support to organs pelvis apes more narrow and set to the back with bipedalism the pelvis widens and is more set to the side to allow for two legged walking valgus angle angle between the femur and the proximal tibia This angle brings the knees in closer to the center of gravity allowing for easier walking without falling over In quadruped apes this angle does not exist as it is unnecessary which is why apes walk in a swaying motion when they try to walk on two legs This angle forms in humans only after they learn to walk which is why babies just learning to walk also walk in that swaying motion big toe apes have an off set fully opposable big toe while human big toes are close to the other toes and are not opposable this is because apes use the feet like hands and need the toe These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute to aid in grasping while human feet need to be rearranged to support walking and balancing on two legs as well as taking all the body weight on two feet ratio of arms to legs in quadrupeds the arms and legs are close to equal length In knuckle walkers and brachiates the arms are longer than the legs In bipeds the legs are longer than the arms In the human fossil record we see this transition from longer arms to longer legs thumbs apes have a small thumb that is not very mobile what makes humans distinct is the ability of the thumb to cross the palm and touch the tips of other fingers Apes cannot do this
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