wk4-Human Evolution

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wk4-Human Evolution by Mind Map: wk4-Human Evolution

1. ancestors,relatives and major transitions

1.1. Darwin didn't mention humans

1.1.1. only one sentence at the end

1.2. not much fossil evidence

1.2.1. first Neanderthals 1956 not much significance

1.3. paleoanthropology

1.3.1. study of human origins

1.4. ancestral relatives

1.4.1. The Versity of Terrestrial Vertberates width of balloon=relative diversity of each grp during the Mesozoic # of primitive mammals shrunk significantly compared to the predominant reptile grps primates evolved about 66 mya just as the last of the dinosaurs flickered out

1.4.2. Primate Evolutionary Relationships 40 mya early primates split into 2 surviving grps we are most recent derivatives of primate radiation relatives and recent ancestors hominids hominoids great apes approximate times of origin of each major primate grp can be read from the time axis compared to the branch point from the main lineage Tarsiers now often placed in own grp Prosimians term used for early primates

1.4.3. Proconsul some apelike features and some monkey like length of trunk , anatomical features and movement date back to 19 mya originated in East Africa lots of fossils found there East African Rift Valley caused by rifts between plates

1.5. Major transitions in human evolution

1.5.1. Bipedalism =walking upright on two hind legs down from trees some dinosaurs and birds are bipedal occasionally primates will use bipedal gaits but not efficiently other primates can go bipedal for short distances hominids comfortable on two legs designed for bipedal locomotion Advantages of bipedalism food resources are scarce motion to look for food less exposure to sun free hands climate change occurring anti predator displays bipedal posture cultural reason competition from new world monkeys and old world monkeys most probably all factors contributed

1.5.2. Running sweating for thermoregulation arched foot and achilles tendon able to walk and run efficiently head stabilization early human scavengers selective pressure 2 get to dead prey b4 others persistent hunting we can run so we can outdo other animals (they overheat) technique is when we run after an animal until it gets exhausted may have lead to a high calorie diet

1.5.3. increased brain size modern chimp brains=350-400cm3 ape ancestors 5mya=same size as modern chimps modern day humans=1,350 cm3

1.5.4. use of simple stone tools fire,spears and other sophisticated tools (stone,bone)

1.5.5. Language complex structure 50,000ya things that show that ancestors started thinking in abstract ways signs and symbols in ritualized burial sites more than just few vocal calls and grunts

1.5.6. Agriculture 10000 ya

1.6. Hominid Evolution

1.6.1. not a simple progression most lineages went extinct cant be sure what species are difficulties in interpreting fossil records dont take into account variation within species

1.6.2. legs(bipedalism) and teeth(diet) and culture came b4 enlargement of brain size

1.6.3. Hoax 1911 discovered in England 1911 assembled Piltdown skull held a modern sized brain ape like large canine teeth and lower jaw other features of early human ancestors with additional fragments over collected over next 2 yrs 1950 found out with modern dating techniques that skull was a well crafted fake

1.6.4. Australopithecines Fossils Australopithecus Africanus Lucy-1974 2 types of Australopithicines main =robust gracile both generally vegetarian Evidence for bipedalism australopithecus=single australopithecines=plural hip and walking muscles indicate bipedal posture femur angle like humans not chimps feet comparison with human and gorilla fossilized tracks at Laetoli (Tanzania) Tool use at start only simple tools used australopithecus garhi Summary major grp of early bipedal hominids small brains only in Africa many forms/species mostly used existing objects as tools

1.6.5. Homo Homo Habilis denizen of Africa lower paleolithic age had basic tools evidence of meat eating more complex hunting and social system anatomical features Homo erectus middle Paleolithic located in China,India, Southeast asia H.erectus/H.ergaster anatomical features food tools fossils Homoerectus lifestyle Homo floresiensis (The Hobbit) Homo Neanderthals H. Sapiens stages of human evolution defined by style and sophistication of tools used Oldowan tools Acheulian tools Two Stone Ages Paleolithic (Old stone Age) Neolithic(New Stone Age)

2. Recent insight from genomics

2.1. 2010

2.1.1. Whole Neanderthal genome sequenced

2.1.2. helped see alignment of genes with normal human DNA (Eurasian DNA )

2.1.3. some genes encode for immune system proteins could have been selected for immunity advantages e.g. resistance to disease

2.1.4. 2-4% of Eurasian DNA comes from Neanderthals

2.2. Hybridisation between Neanderthals and humans happened

2.2.1. reproductive inbreeding was very low

2.2.2. maybe they avoided each other

2.2.3. hybrids might have had low fertility/survival

2.2.4. Mathias Currat

2.3. denisovans (Siberia)

2.3.1. archaic hominin grp

2.3.2. found three theath and a toes bone 41,000ya found in Siberia

2.3.3. Amazingly well preserved DNA siberian average temp=0C able to sequence the genome showed discovery of new species that is more related to Neanderthals

2.3.4. common DNA with Neanderthals 600,000 yrs ago

2.3.5. very little diversity within species chromosomes were very simple interbreeding with Homosapiens 4-6% of Melanesian genomes are from Denisovans suggests that early modern humans left Africa 60,000 yrs ago

3. What about today

3.1. extent to which humans continue to evolve

3.2. Does NS still act on humans

3.3. Misunderstandings

3.3.1. evolution=genetic change

3.3.2. evolution not only through NS genetic drift and SS also involved in driving evolution

3.3.3. Medicine can reduce the effect of deleterious traits many alive who would have died many still have limited access to medicine

3.3.4. Even with best medical care there are diff. in reproductive success

3.4. Pathogens and disease

3.4.1. e.g. Spanish Flu(influenza) pandemic in 1918 killed 1-3% of the world's population

3.4.2. AIDS

3.4.3. Dengue,Typhus,Malaria

3.5. Other examples

3.5.1. study kept track of human immigration in Canada looked at fertility of different individuals depending on locations

3.5.2. Lactose intolerance culture shaped genomics

3.6. Genetics of our behaviour

3.6.1. most behaviour of animals is genetically predetermined could be same for humans

3.6.2. evolutionary psychology subconscious things affect decisions e.g anorexia

3.6.3. HNC profiles odours tell info about immune system pheromones help identify mates based on MHC profiles