Year 13 Human Evolution

Year 13 Human Evolution90719 External Achievement Standard

Taxonomy.. Again!1. ORDERTaxonomyKingdomPhylumClassOrderFamilyGenusSpecies

AnimaliaVertebrataMammaliaPrimatesHominidaeHomoSapiens

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Why are we in these groups?Kingdom: AnimaliaConscious, not plants or protistsPhylum: VertebrataHave vertebral columnClass: MammaliaMilk feeding, live young

Order: PrimatesAdaptations associated with arboreal (tree) life1. Pentadactyl limbFive digits (most mammals have lost at some)Bones of lower arm and leg are separate giving more mobility (most mammals have at least partly fused now)Plantigrade foot posture where the entire foot contacts the groundForelimbs prehensile (can grasp objects branches)

Order: Primates2. EyesEyes face forwards 3. Stereoscopy (3-D Vision)Binocular vision in which the visual fields overlapBrain receives input from both eyes to both sides of the brain giving ability to judge distance

Stereoscopy

Order: Primates4. Colour visionPhotoreceptors- Rods and cones on retinaImportant for identifying edible fruit5. High Visual AcuityCan see fine detail due to the fovea (sensitive spot on the retina with a nerve fibre per photoreceptor rather than one per group)PrecisionOrder: Primates6. Well developed clavicleHelps with weight bearing, swinging and grasping7. SkinTips of the fingers and toes have ridges which increase the sensitivity to touchPrecision8. Nails instead of clawsGive broad base of support for fleshy end of finger- good for grasping

Order: Primates9. Smell reduced- can not use this to track prey10. Highly developed balance and awareness of body in space (Proprioception/ Kinaesthetic awareness)Essential for balance up trees, and ability to sense limb positions in space

Order: Primates11. Very large brainEssential for processing information rapidly12. ReproductionInvest greater resources in each offspringLong gestation as young need to be developedCarry youngSingular youngPectoral mammary glands as young suckle in sitting position

Order: Primates13. Singular uterus

Order: Primates14. Sitting postureSit in an upright manner to enable head movement without affecting balance

Order: Primates15. Social life: Live in groupsProtectionFind food LearnFind matesRearing of young

2. FAMILYFamily: HominoidsApes rather than monkeys (Old World Monkeys family: Cercopithecoidea)Apes, gibbons, orangutan, chimp, gorilla, humansSame as Cercopithecoidea as have 2 premolar teeth in each half of each jawMenstrual bleedingDIFFERENCES RELATED TO BrachiationSwinging in Branches by armsFamily: HominoidsBrachiation1. Very powerful arms that are longer than legs2. Flatter chest3. Scapular is at the back rather than the side4. No tail5. Can supinate forearm6. Larger clavicle

Family: HominoidsBrachiation7. Short lumbar region of spine8. More highly developed brain9. Lower molars have a Y-5 cusp patter10. No sitting pads (Ischial callosities)11. African Apes: Knuckle walking

Describe how each of the following can be related to arboreal lifeRidges on the skin and fingertipsA well developed clavicleSeparate tibia and fibulaProduction of single youngLong gestation periodStereoscopic visionColour visionLarge brain3. GenusFamily to GenusThe family of Hominoids splits into Genus 1: HomoGenus 2: AustralopithecusGenus: HomoLarge brainMore human likeGenus: AustralopithecusBipedalBrain significantly smaller but bigger than a chimpCanines reduced and non protrudingShorterLarge degree of sexual dimorphismNo evidence of stone tools but perhaps stick tools(Now extinct)Other genus:Chimps, Bonobos- PanGorilla- GorillaOrangutan- Ponga

4. SpeciesSpecies: HomosapienBipedalismHumans are the only primates that can stand and walk on two legs for extended periods of time

Species: HomosapienBipedalism1. Body is concentrated into a narrow column above feet therefore body weight is supported by bone2. SkullForamen magnum is situated in the middle of the skull as opposed to being at the rear as in apes

Species: Homosapien3. Backbone (COG)Has a gentle S shape to take weight directly above hipsApes have one curve and weight is carried forward of hips

Species: Homosapien4. Short hip girdleIn quadrupedal species the hip bone is longerHumans have a bowl shaped hip bone which is smallerThis help to transmit and carry weight better

Species: Homosapien5. Knee jointsDirectly below hip girdle so can walk without swayingWhen one leg is lifted, the other is only slightly out from the center of gravity so less tendency to swayA chimp has to lean the other way to keep balanced

Species: Homosapien6. FootHuman foot is a platform through which thrust occurs to push forwardLarge big toe that points forwardChimps foot is a prehensile structure therefore big toe points sideways High arch in human foot to make long distance walking possible

Species: Homosapien7. Hand- ThumbLongerSaddle joint that allows oppositionFlexor pollicis longus flexes the tip of the thumbGives precision grip rather than just power grip

Species: Homosapien8. Teeth and JawsTeeth and jaws much smaller in humans than apesCanines about same size in males and females of humansCanines significantly larger in males than females of apesBowl shaped dental arcade in humans compared to the U shape in apesNo diastema in humansSpecies: Homosapien9. Brain HUGECortex of Cerebrum is folded lots giving more volume and surface areaGives reasoning, maths, language, artistic skills, abstract thought, imagination, perception of sensesCerebellum is large giving good balance and muscular co ordination

Species: HomosapienSpeechDevelopment of Brocas area giving the ability to organise sounds into meaningful sentencesWernickes Area is well developed giving the ability to interpret the sounds heard

Questions1. Discuss the importance of diet in the evolution of the primate brain (E)2. To which class of vertebrates to primates belong?3. Three important characteristics of primates that have contributed to their success are; Grasping hands, Well developed vision and Highly developed vocal communication.Explain why each of these characteristics is important for arboreal life (M)4. Ape and human hips, legs and feet differ frome ach other. Explain how one of these would differ between apes and humans and why it is different. Relate this to locomotion (M)

5. The Journey to todayAustralopithecines to Homos =](Different genuss!)Genus: Australopithecines(Bipedal, Brain significantly smaller but bigger than a chimp, Canines reduced and non protruding, Shorter, Large degree of sexual dimorphism, No evidence of stone tools but perhaps stick tools, Now extinct)Earliest known pre-humansFossil record of 4 million to 1 million years ago9 species within this genusFossils found in Africa, mostly in the East African Rift ValleyThis is an area where two tectonic plates are moving apart and volcanic activity caused the burial and fossilisation of animals including pre humans

Genus: AustralopithecinesFossils show that bipedalism preceded brain expansionGiving more freedom to the hands, bipedalism paved the way for intellectual activities such as tool makingAccording to teeth and skull anatomy, Australopithecines can be seen as Robust or Gracile (slender)Robust types are thought to be specialised herbivores and evolutionary side branchesMost became extinct and did not lead to humans but side branches of the evolutionary treeAustralopithecines AfricanusSum up and write down what you call tell about this species by your evolutionary tree.Forward foramen magnum therefore considered to be bipedalSmall canines, parabolic tooth row, less protruding jaw, lack of simian shelf, and lack of diastema

Australopithecines Africanus

Australopithecus AfarensisSum up and write down what you call tell about this species by your evolutionary tree.LUCY!!Bipedal due to features of the knee, hip, big toe and valgus anglePrimate like (primitive) due toStrong sexual dimorphismSmall brainLarge caninesParallel side tooth rowsSlightly curves and longer phalanges

Australopithecus Afarensis

Australopithecus Robustus and Australopithecus BoiseiSum up and write down what you call tell about this species by your evolutionary tree.Both seen as robust speciesDifferent to A. Africanus and A. Afarensis due toHuge flat molars (herbivores)But smaller incisors and caninesProminent sagittal crest*Wide cheek bones (zygomatic arches)** Suggests massive temporal muscle to raise the lower jaw powerfully

Australopithecus Robustus and Australopithecus Boisei continued..Huge molars and jaw muscles, as well as small incisors and canines suggests. (pg. 396 Study Guide)Australopithecus Robustus (South Africa) and Australopithecus Boisei (East Africa) continued..

Ardipithecus RamidusSum up and write down what you call tell about this species by your evolutionary tree.Forward foramen magnum suggesting bipedalismRelatively large caninesLonger arm bones than A. Afarensis

Australopithecus AnamensisWhos great great great great great Grandad is this?Sum up and write down what you call tell about this species by your evolutionary tree.Humerus and tibia that have been found show bipedalismLarge canines, thick enamel covering teeth

Australopithecus Anamensis

The Evolution of BipedalismThe most important event in human evolutionFossils and datingFossils are created when an organism that dies is covered in mud, river sediment or volcanic ash. The hard parts are replaced by minerals of surrounding materials (usually sedimentary rock). Older fossils are found deeper.

How old are the fossils? Dating!Absolute datingThis gives you the date in years (from 10s of thousands to 100s of millions)This is done through knowing the rate at which radioactive isotope decay at. The rate of decay is constant and called the half life. Commonly carbon 14 and carbon 12 are used to date wood or boneCommonly potassium - argon is used to date rock in which a fossil is lying which is OLDER than 400,000 years

How old are the fossils? Dating!Relative datingTells you the age of a fossil relative to anotherE.g this fossil is older than that one.Can do this by measuring the nitrogen/ fluoride ratios of two bones, the one with less is older as bones lose this as they get older