Week 10 Early Hominids 6 steps to becoming humans 04 01 2014 o bipedalism 6 mya o lose large projecting canines 5 5 mya o material culture 2 5 mya o hyoid bone speech shape changed to make it possible to produce speech 2 5 mya o cooperative hunting w tools long distances 1 mya o domestication 11 000 BCE o over all this time brain size was increasing o 3 obligate steps are bipedalism lose canines and material culture bipedalism o foramen magnum hole in the back of your skull and allows your spine to enter at a 90 degree angle o pelvis shortened from front to back o long legs don t need long arms anymore o double arched foot allows flexibility and spring step o non opposable big toe hallux non honing chewing o apes large projecting canins act like knives large masticular muscle pulls sideways o hominids thinner tooth enamel not dealing with crunching down on hard things blunted small teeth masticular muscle pulls vertical crush we grind our food apes shred their food thicker tooth enamel Why did homonids emerge o Darwin s Hunting Hypothesis reason for hominid emergence Bipedalism freed hands for carrying weapons Humans needed and had higher intelligence to make tools Once tools acquired there was no need for large projecting canines for hunting or defense didn t know about chimp tool use we know this doesn t fit bc we have evidence that contradicts o Patchy Forest Savannah Hypothesis Forest got patchy with drying and cooling in East Africa Food became more dispersed Bipedalism allowed for easier travel between forest patches and to carry food o Provisioning hypothesis Monogamous fathers increase reproductive success by providing food and predator protection to mothers and offspring also need bipedalism for this Fossil skeletal evidence shows little sexual dimporhism suggests males were cooperative and didn t compete with eachother Little sexual dimorphism more cooperation less male competition o Advantages increased ability to see long distances and over grass greater ease to transport food and offspring ability to run long distance free hands future tool making and use energy savings Bipedalism Tradeoffs o Negatives more exposure to predators they see you when you see them standing and walking while carrying can lead to back injury arthritis slipped disks over long term hard on circulatory system to pump to brain and legs varicose veins if foot is injured cannot travel Evidence of Bipedalism o pre australopithecines o Australopithecines we have chad found in Africa have foramen magnum so we know he was bipedal Orraorin tugenensis have femur and other leg pieces that show bipedalism Ardipethecus kadabba modern day Ethiopia see loss of the canines so transition of teeth Ardipethecus ramidus ardy had opposable toe but also had evidence of bipedalism Had the large canines but they were smaller Woodlands grasslands lake shores Australopithecus anamensis 4 mya molars grinding non honing canines Australopethecus afarensis lucy lost opposable toe but had curvature in finger bones that would assist her in climbing mix of hominin and ape characteristics Australopethicus platyops lived at the same time as lucy but far more forests flat teeth face small brain Australopethicus aficanus grassland areas long arms nad short legs no curved fingers Australopethecus garhi Related to homo Lived in grassland areas and along lake shores think about food sources Oldowan pebble tools coppers scrapers diggers homo habilis used these not austral Austalopethecus aethiopicus has saginal crest skull flat face larger brains really big back teeth Australopethecus boisei larger brain jaw muscles Austral robustus really big teeth and thick enamel on teeth Probably ate really hard fruits and nuts Austral sediba very recent find in southern Africa small australopethicine very similar pelvis to us skin imprint in the stone that the fossil was found in so they can tell about the skin Summary of changes o Pre australopethecines to australpethecines slight increase in brain size modified honing to non honing canines lost vegistal orboreal traits lost hallux and gripping mechanisms so only bipedal now o australopethicines to homo big increase in brain size size reduction in our face back of cranium gets bigger teeth size reduction front face gets smaller o all changes due to envionrmental pressures 4 3 14 The Rise of Homo Spp plural of all the homo species Obstetrical Dilemmas o Problem bipedalism requires narrow bony birth canal but increased intelligence bc of tool making and hunting requires bigger skull Harder for big skull to come out of narrow birth canal o We are 2 to 3 times the brain size of australopithecine o We also have broad shoulders which makes it difficult to come out of the birth canal o Adaptations come out Shortened gestation so that we are smaller when we Relaxin hormone when a women goes into labor her body releases this hormone and it relaxes ligaments and joints in the pelvis Rotation in the birth canal Broadended pelvis wider hips are an outward sign that birth canal is bigger Unfused skull in newborn easier to come out of the canal Birth assistance social belonging to a social group helps facilitate birth Males have narrower hips so they have easier movement o Females have wider hips our spines are not at 90 degree angle walk a little differently Why are tools important o Being able to hunt our own food helps us eat more better food o Fire cooking lead us to who we are today Allowed us to access foods that would be poisonous or unable to eat Opened up new supplies of food and more calories More calories more energy that the brain is consuming more intelligence Homo Habilis o 2 5 1 8 mya o found Oldavai Gorge Tanzania also Kenya Ethiopia Malawi and South Africa o lived simultaneously with Australopethicus boisei rounded skull gait similar to australopithecines smaller jaw and teeth bigger brain brain always gets increasingly bigger better precision grip TOOLS o Adaptive Flexibility 2 5 mya envionrment warmer temps more habitat diversity incl grassland habitat diversity indicates new food sources more enegery for brain increase in brain growth homo habilis teeth and tools scavenging plant foraging food processing used the oldawan tools Homo Erectus o 1 8 3 mya o new improved features o teeth jaws face smaller as your brain gets bigger the back side of your cranium has to get bigger so the front side of your cranium gets smaller o Heavy browridge helps in sunny places homo sapiens are the only