Origins: Animal, Human and Sociality
Origins: Animal, Human and Sociality BIOL 1001-001
U of M
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This 7 page Class Notes was uploaded by Mickayla Notetaker on Tuesday November 24, 2015. The Class Notes belongs to BIOL 1001-001 at University of Minnesota taught by Annika Moe and Craig Packer in Summer 2015. Since its upload, it has received 27 views. For similar materials see Evolution and Ecology in Biology at University of Minnesota.
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Date Created: 11/24/15
Lecture 19 Animal origins Monday November 16 21115 1112 PM Intro diversification of the animals Autotrophsproduce own sustenance Heterotrophsobtain sustenance through other organisms Need Digestive system sense organs Mobile animals need circulatory system musculoskeletal system Retention of traitshomologythe forearm example ancestor had a certain bone structure and can be seen now in extant organisms Parallel evolution analogy the dolphin and shark similarities Being in one environment it is advantageous to have certain traits Start out at singlecelled protists Multicellularity colonial protist and sponge Radial ancestryspokes on the wheel symmetric Single orifice that allows food to come in and waste out Jellyfish medusa anemone Bilateral ancestrySymmetrical left to right flat worms and other worms Paedomorphosiswhere adults retain the juvenile traits of their ancestors Coelomate ancestry coelom body cavity allows for greater mobility without getting all twisted up Protostome branchby the 32nd division they have a spiral symmetry Opposite ends of mouth and anus than Deuterostome Mollusks and arthropods and earthworms last two have segmented bodies Arthropod body size are restricted by their exoskeletons Deuterostome branchhave a radial symmetry like the radial ancestry echinodermsStarfish sea urchins Chordateslancelets sea squirts no brain or eyes but the early forms for a endoskeleton Flexible endoskeletons fish Homologiestype of symmetry raidal vs bilateral Paedomorphosis ancestral larvae gt adult descendants Openclosed gut coelom Developmental pathways esp gut All animals are multicellular Analogies limbs fins Circulatory system Internal organs eyes hearts brains Animals diversified from a single common ancestor and developed the necessary traits to obtain food Evolutionary innovations arose from 1 Moving from the oceans to fresh water a Acquisition of lungs in bony fish Allows fish to breathe air instead of through water 2 Moving from water to land a Paired appendages in amphibia Needed legs to walk on land instead of swimming 3 Moving further onto dry land a More efficient lungs waterproof skin and eggshells in Reptilia 4 Becoming active at night a Endothermyhaving a metabolism to keep them warm 5 Living in a threedimensional habitat a Large brain size New Section 1 Page 1 6 Relying more on learning than instinct All major vertebrate lineages arose within first 200myrs of living on dry land Therapsids the ancestors to the mammals Origins of the mammals covered with hair complex teeth females secrete milk Monotremecloaca single urination defecation and egg laying like reptiles but they secrete milk and covered in hair so mammals Marsupials reproductive tract is vastly different Gives birth to an embryo that finds its way into the pouch and latches onto a teat to complete its development Eutheriansplacental mammals long time developing in the womb and relatively advanced when its born Biogeography tree shrewgtprosimianslarge eyesgt New world monkeystail is like another appendage full usage and sideways facing nostrilsgtOld world monkeysgtApes New Section 1 Page 2 Lecture 20 Origins of Humans Tuesday November 24 2 15 112634 AM Remember from last lecture the evolutionary innovation that arose from living in a threedimensional world was that there was an enlarged brain size This is fundamental when talking about the evolution of humans Toumaifound in the Sahara desert Thought to be the last common ancestor of chimps and humans abt 64mya Its brain size was smaller325cc than a modern chimp350cc Ardipithecuslarger stature and shape of pelvis indicates they could walk upright but were adept at climbing trees Again they had a smaller brain325cc size than a modern chimp350cc Lucyfound in Ethiopia Had a larger brain475cc than even a modern day chimp350cc and clearly walked upright Whereas a chimp would walk crooked She was also a toolusing meat eater they used tools to butcher animals to eat Her species was a common ancestor to the genus Homo Relationships between brain size and body size The bigger the body size the bigger the brain size but it seems there has been selection favoring intelligence The mammals have bigger brain sizes than that of another species of the same size Brain size gets rapidly larger as we move toward modern species which is now around 1800cc39s Proximal mechanisms for rapid evolution of quotHumanquotness 0 Regulatory genes control how much RNA is transcribed and thus the extent of protein synthesis In some regulatory genes human genes are producing much more proteins than the other great apes but others are way less active than the apes Ecological factors associated with large brain size 0 Complex environment 0 Habitat arboreal species gt burrowing specieshas to do with the amount of complexity that daily activities in the habitat have 0 Food distribution fruiteaters are larger brained than leafeaters the fruiteaters have to determine which are good fruits to eat and has to gather them while the leafeater can take any leaves that are around 0 Reliance on memory 0 Foodstoring bird species are relatively largebrained have to remember where they stored their winter supply of food 0 Chickadees have memory neurons in harsh climate MNgtKS figure out how to survive for a longer winter in MN than in KS How smart are they really Caledonian crowuses a twig as a tool to dig out food to eat from last lecture 6Relying more on learning than instinct 0 Culture the ability to pass on behavior through social learning 0 Mammals are essentially defined by the physiology of maternal care secrete milk and take care of offspring for a long time compare to other species so a greater chance for the offspring to learn skills from their mother 0 Chimps in west Africathey forage nuts that are too hard to crack open with their teeth and they bring the nuts to a place where they can smash the nut with a rock The offspring observe this and develop similar behaviors as their mother39s New Section 1 Page 1 Genus Homo 0 Defined by their ability to make tools 0 As the species evolved the complexity of the tools increased 0 Homo erectus are thought to be the first hunters and the first to create and use fire abt 400kya and they had small teeth which implied they might have been able to cook Lasted the longest of any hominid species abt 15my Always used the same toolkit for that 15my First hominid with a modern gait landed on heel pushed off on forefoot which was possibly an adaptation for running and long distance travel First species of Homo to leave Africa Africagt Asia 1217mya 0 Homo Floresiensis adults were three feet tall had more complex tools than erectus and Lucy and it occupied the island of Flores from 880000 to 12000 ya Debate whether it descends from homo habilis or even Australopithecus Data suggests that it is more closely related to apes than humans or the homo genus But the smaller brain and other traits indicate descent from H habilis Neanderthalsleft Africa 300000ya 2nd to leave Africa 0 Lived in Europe and middle east Made tools and quotcrudequot art like sculptures and painting Homo Sapiens third hominid to leave Africa 0 quot45000ya if this happened H Sapiens coexisted with Neanderthals for 20000yrs in Europe and Middle east quotginger genequot found only in Europeans and originated 100000ya 4 of genes in Europeans and Asians come from Neanderthals Neanderthals didn39t go back to Africa so there was no interbreeding with Africans The absence of Neanderthal mitochondria in modern humans suggests quottheirquot males mated with quotourquot females Modern humans originated in Africa 100000yrs ago 0 They had more sophisticated toolkits Art sculpture music and religion Spread from Africa to Europe Asia and Australia Artist Workshop found in South Africa Had mechanisms to create paint and other artist objects There are sophisticated sculptures and art found also flutes that were made out of bird bones and fired clay ceramics What made all these innovations possible Must have been Language Evolution of Language 0 Modern languages reveal common ancestry Languages that are similar show a common ancestry with the people of those languages The likely origin of language was in southwest Africa Emphasizes the origin of humans in Africa 0 Study of a family with a severe speech disorder shows that the FOXPZ gene is responsible for facilitating proper language the affected members of the family didn39t have functioning copies of it The human variant of FOXP2 gene which allows us to talk originated lt120000ya It is pleiotropic and influences both facial movement and neurological development Key events in Human Evolution 0 Enlarged brain size 0 Proximate cause changes in regulatory genes 0 Ultimate cause complex habitat reliance on memory 0 Consequence culture 0 Language 0 Proximate cause Human Variant FOXP2 gene 0 Ultimate cause Need for group coordination O Consequence Art music religion largescale societies Modern Evolution 0 200 Loci in each race of humans show active selection in different places suggesting they are still adapting to local challenges on each continent Livestock domestication900013000ya 0 Continuous close contact with other species Rinderpestgtmeasles New Section 1 Page 2 0 Change in diet dairy products Lactase enzyme appeared 300010000ya Evolved 4 separate times 0 Plant domestication500010000ya 0 High human population density near water Standing watergtmosquitoesgtMalaria Genetic resistance to malaria new alleles at 4 different loci appeared 33009300ya Rapid evolution in humans 0 Tibetans live at high altitudes which requires them to breath only 60 as much oxygen as at sea level but they don39t get mountain sickness Compared to the Han Chinese the Tibetans show evolutionary change in 230 genes as adaptation to high altitude life The Han and Tibetans only split apart 3000ya 0 Skin color and sunshine 0 places in the world that receive more UV rays are places where people who live there have darker skin color Chimps a cousin species in Africa have white skin but thick body hair that protects the skin from too much sunlight Too much sunlight results in breaking down Vitamin B complex which causes birth defects and male sterility so dark skin is necessary in strong sunlight Dark skin blocks sunshine inhibiting vitamin D production causing skeletal deformities light skin necessary in low sunlight 0 Hair and sweat 0 Fewer hair follicles allows I More sweat glands and more rapid evaporation of sweat Humans are hairless so as to be able to sweat during bursts of physical activity Exercise gt increases brainderived neurotrophic factorgtimproves metabolism and other things that keep our brain and body healthy New Section 1 Page 3 Lecture 21 Evolution of Sociality Tuesday November 24 2 15 1225 PM Benefits of grouping 0 Behavioral ecology the adaptive significance of behavior Many animal species are social animals and live in large groups Probably an adaptation Prey 0 Dilution effect less likely to be attacked in a larger group One animal by themselves is guaranteed to be eaten but if they are one of a larger group their chances of being eaten is 130 or so 0 Selfish herdreduces own risk of being attacked by the predator wildebeest with calf will go on the opposite side of the herd to avoid the predator and use the companions as cover to protect the baby 0 Confusion effectreduces chances that attack will succeed Depends on similarity schools of fish will swarm all around and the similarity and chaotic movement confuses the predator and the attack isn39t as successful Individuals reduce their risk of being caught by predators by living in groups Predators 0 Improves hunting success against largedifficult prey Hunting dog in a pack almost always succeeds in attacking a larger prey 0 Improves access to resources through group territoriality Lions will attack other lions that come into their territory and kill them They are protecting their territory and resources 0 Geography of savanna landscapes lions need to ambush their preybut cover is sparse When they find a good hiding place they will defend it fiercely because they are able to get more food in that territory 0 Sociality is most likely to evolve 0 High population density 0 Savanna landscape geography where some places are better for survival if you live there 0 Group selection can work when larger groups cooperate to kill smaller groups The selfish trait is not selected for because you need to work with others to survive attacks from other groups 0 Gang attacks in chimps and humans I Territoriality seeming to be the basis for the attacks on other individuals from another group 0 Behavioral ecology of sociality 0 Group living confers individual advantages to predators and prey O In some circumstances group selection can become as important as individual selection 0 Evolution of Human Behavior 0 Human nature I Genetics of complex human traits I Origins of large scale societies 0 Human societies I Huntergatherers50000ya I Pastoralists10000ya I Agriculture6000ya I Citystates3000ya I Nationstates1000ya 0 Evolution of Human society New Section 1 Page 1 0 Measuring heritability compare similarities of identical twins with fraternal twins Control for environment by comparing twins reared apart Proportion of similarity due to genetics is called heritability I Heritability can only be measured in populations not specific individuals I Perfect heritabilityh21 grown children are exact same height as their parents I No heritabilityh20 grown children may be any height I Partial heritabilityOlth2lt1 tall parents have taller children on average I Behavioral traits are partially heritable Homosexuality is thought to be heritable 60 men and 25 in women 0 Homosexuality I 36 of people in every human society I Possibly maintained by pleiotropy III Genetic trait that is advantageous to one sex but alters sexual orientation in the opposite sex 0 quotgay man genequot on the X chromosomehighly fertileattractive heterosexual women have higher reproductive success while sons may become gay 0 quotlesbian genequotHighly masculine men have higher reproductive success while daughters may become lesbians O Religiousness50 I Religion is a human universal I Neurological basis of religious feelings and attitudes acceptance of supernatural is higher in Swedish men with fewer serotonin receptors III Epileptic patients that frequently experience quotreligious ecstasyquot have a significantly smaller right hippocampus I If there is a biological basis for religiosity what are the selective advantages III High levels of religiosity significantly reduce the risks of depression in adolescent girls Through a greater sense of connectedness III High levels increase cooperativeness in adults especially men Complex human behaviors are often influences by genetics Many of these traits affect survival and reproduction Human Ethics 0 War a human universal I Patriotism is probably innate as is dehumanizing the enemy I Moral codes also shame men who don39t put their lives on the line quotshamingquot may also be innate Human cooperativeness O Reputationmemory we know who you are and we saw what you did I Language 0 Group membership I Huntergatherer bands are egalitarianresources are shared I Cooperation within the same group but hostility to neighboring groups as in Chimps and lions I Within a vast society religious institutions restrict membership to a subset of well behaved individuals and monitor their behavior 0 Transition from huntergatherer bands to tribes facilitated by religious ideas that untie large numbers of people Tribes could quickly mobilize many men for warfare forcing neighboring bands to tribalize too or be defeated Good for common group 0 With the advent of agriculture wealth could be passed to the next generation Societies became despotic as accumulated resources Good for self family 0 Original social system was egalitarian and the longing for fairness is universal New Section 1 Page 2
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