Human Evolution Forces Driving Change Natural Selection o Act on present variation o Environmental changes o Selection against traits not for them Gene Flow and Genetic Drift o Gene Flow Migration Gene exchange across populations o Genetic Drift Random change in frequency of alleles Chance events Bottleneck founders effect Mutation o Change in genetic code o Only source of new genetic material o Neutral advantageous deleterious Hominin evolution Hominin o Humans and their earliest ancestors Change in time and structure Epochs o Point in time Pliocene 2 0 5 0 mya Pleistocene 0 01 2 0 mya Holocene Present 0 01 mya Structure o Walking on two feet brain expansion What came first Bipedalism or big brain Bipedalism Lucy Bio cultural evolution Definition of a Hominin Locomotion o Bipedalism Later development o Larger brain size o Tool manufacturing o Language Pre HOMO Hominin Patterns Each had restricted geographic ranges Still somewhat tied to the trees No great increase in brain or body size Early HOMO evolutionary trends Smalled teeth Less Prognathism Brain size expansion o 400 cc 600 900 cc Defining the genus HOMO Physical attributes o Relatively large brain o Small face and jaws including teeth Behavioral attributes o Dependence on material culture for survival Homo Habilis Found only in Africa o Wider distribution that earlier Hominin o Species expansion First Homo found with tools Tool use o Brain expansion o Oldowan industry Core tool Single face hammer stone Preconceived shape o Tool making and use now central to adaptation Tools increase capability to eat greater range of Homo erectus A new kind of Hominin food Increase in o Body size o Brain size Different cranial shape o Brain organization and enlargement Changes in limb proportion o First obligate biped Found outside of Africa Geographic diversity o One genus Homo Species number debated Tall stature Large brain o Closer to modern human size Lengthening of limbs and legs o Obligate biped Going global o Evolved in east Africa Africa Georgia Java Asia ergaster o East Africa Nariokotome Boy Nearly complete skeleton Almost 6 ft tall at 11 o Ethiopia Female pelvis Large brained babies o Direct ancestor of Asian and European H erectus Dmanisi o Oldest hominin outside of Africa o Georgia Indonesia o Java Man first recognized human ancestor increase in brain size o Ngangong Java Later than H erectus in the rest of the world China o Similar shape to Java finds Zhoukoudian Cave Fire maybe Lantian Fire Europe o Oldest Hominin in W Europe Beeches Pit England Burnt animal bones Anthropogenic layers What accounts for these rapid change Cultural expansion Bio cultural evolution Tool technology Oldowan tools o Building toolbox Achulian tools o Found at most Homo erectus sites Not widespread in Asia o Bi face hand axe o Material from other places Clactonian industry o England H erectus sites More forethought and planning Able to process foods differently Fire Use Greatest contributor to human evolution Bigger brain higher energy budget Nutrition o Breaks down the food Releases nutrients Less work to digest o Less toxins o Better nutrition better reproductive fitness larger body size Protection Promotes cooperation Pre modern humans Paleo environment o Don t need trees or arboreal adaptations o Pleistocene Ice Age o Advances and retreats of continental sheets o Glacial periods Less rainfall and climate desert expansion Restricted movement o Interglacial periods More rainfall Movement possible o Northern regions more affected Climate change everywhere Geographic dispersal o Widely distributed in the OW Africa Asia Europe H neanderthalansis o 175 000 30 000 ya roots to 500 kym contemporaneous with H sapiens may have interacted evolutionary enigma o Europe and western Asia o Structure 40 yr at time of death intentional burial Larger brain than modern H sapiens Very robust Large muscles Larger bodies Cold weather adaptations o La Chapelle aux saints Old Man of La Chapelle missing teeth care for the elderly prehistoric bad day o Moula Guercy Cave Broken skeletal fragments Processed for consumption Canabalism o Shanidar Cave Shanidar 1 male severe traumatic injuries but lived to be 30 45 yrs o communal care o Paleolithic culture Prepared core technology Levallois technique No longer a core tool Now using flakes from the core Controlling flake size and shape Intelligence knowing how to break the rock the right way Built temporary shelters and lived in caves Hunted Simple technology lots of animals remains Continues use of fire Mousterian tool industry Worked flakes More forethought and planning and Tools for different functions scrapers skill points knives Frison effect Hunters Re sharpening changed shape Close range weapons Lots of injuries o Culture Speech Capable of speech Hyoid morphology Gene influencing speech production identical to modern H sapiens Ritual behavior burials Intentional burials Possible associated grave goods o Genetic evidence mtDNA and nuclear DNA mtDNA shows more dissimilarities between Neanderthal and modern H sapiens But only a tiny portion of the human Nuclear DNA shows some similarities AND better represents the total between the two genome genome Some European populations have 5 6 Neanderthal DNA More evidence needed but probable connection