Human Evolutionwww.okc.cc.ok.us/deanderson/index/human_evolution.ppt

The Evolution of Humans

Theory of EvolutionScience has overwhelming evidence that all life is constantly evolving

Natural SelectionOne mechanism of evolutionMain concepts of natural selectionOverproduction of offspringInherited variation in offspringCompetition Best adapted in a given environment survive and reproduce to increase their kindThey are naturally selected

Overproduction of OffspringElephants (very slow reproductive rate)If all the offspring of one elephant pair survive and all their offspring survive then:750 years = 19,000,000 elephants1200 years = Enough elephants to cover the earth!BeetlesA handful that weighs 10 mg each82 weeks61,000,000,000,000,000,000,000 tonThe weight of the earth!

The Evolution of Humans

Variation of OffspringOffspring of the same parents are different from each other

CompetitionSince more individuals are born than can survive for an extended period of time, they compete for resourcesFoodLiving spaceMates

Best adapted to a given environment are selected to surviveBrown bearsAdapted to survive in OklahomaPolar bearsAdapted to survive in Alaska

The Evolution of HumansThe Ecological TheatreThe Stage: East AfricaThe Setting: A time of unrest...GeologicallyThe rift zone - uplifts, rifting, volcanoesClimaticallyA series of glaciationsGlobal climate changeChanges in sea level

Sequence of Human EvolutionHundreds of fossils have been foundSome of the major fossils will be discussed in this presentation

Australopithicus afarensis3.5 million years agoNicknamed LucyWalked uprightSmall brainSkeleton human likeFeetPelvisUpright stance

Comparative AnatomyGorilla pelvis adapted for knuckle walkingHuman pelvis adapted for upright walkingLucys pelvis very similar to human pelvisLucyHumanGorilla

Knuckle WalkingRequires an elongated pelvis and long arms

Lucys pelvis allowed her to walk like a human instead of an ape.

Fossilized FootprintsFootprints left when a a pair of Australopithecines walked in the ash of a recently erupted volcano

Skull AnatomyThick brow ridges like a chimpanzeeCranial capacity 400 cc. Chimp 350 cc.Teeth similar to human teeth

Lucy: A Transitional FossilTransitional fossil shows characteristics of two kinds of animalsRepresent the transition from one organism to anotherApe characteristicsSkullCranial capacityHuman characteristicsWalked uprightFeetPelvis

Australophithicus africanus2.8 million years agoCranial capacity 460 cc

Homo habilisCranial capacity 630 ccFlatter face than AustralopithecinesUsed toolsNicknamed handy man

Homo erectus1.8 million to 35,000 years ago1,000 cc cranial capacityLarge brow ridgesSloping foreheadMore advanced tools than H. habilis

Homo erectusSkeleton very similar to modern manUsed fireTraveledFossils found in Africa, Europe, China, Indonesia

Homo neanderthalensis135,000 to 25,000 years agoCranial capacity up to 1750 ccLarger than modern manNo chinSloping foreheadBuried dead with tools and flowers

The Evolution of Humans The Cro-Magnons and the Neanderthals

Homo sapiens200,000 years ago to presentPhoto is a skull 100,000 years old1400 cc cranial capacityVertical foreheadPronounced chin

The Evolution of HumansWhat about the Neanderthals?

The Evolution of HumansWhat about the Cro Magnons?

Modern Homo sapiensSmall front teethSmall brow ridgesRounded cranium

Sequence of Human EvolutionOne of several possibilitiesHomo sapiens

Evolution of SkullCranial capacity increases for a larger brainFace become flatterBrow ridges become smallerForehead becomes higherChin develops

Tools used to learn about our evolutionary pastStudy of fossilsComparing DNAComparing chromosomesComparing protein sequences

PaleontologyStudy of fossils Allows us to see anatomical similarities between us and organisms that lived in the pastAllows us to see how our ancestors have changed over time

Comparing DNAHuman DNA compared to:Chimpanzee 99% sameGorilla97.7% sameOrangutan 96.3% sameAnother human 99.9% same

The Evolution of Humans The Great Leap ForwardDue to evolution of a mechanism that allows speech and language?Characterized by the appearance of... Use of symbols...Complex tools...Innovations in hunting techniques and strategies...Increased population size, development of social systems...Houses, boats, long distance trade, ornaments Art, music, rituals...

The Evolution of Humans