Unit 2 Class Notes - Week 3
Unit 2 Class Notes - Week 3 ANTH260
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This 6 page Class Notes was uploaded by Jessica Shook on Tuesday March 3, 2015. The Class Notes belongs to ANTH260 at Washington State University taught by Luke Premo in Fall. Since its upload, it has received 162 views. For similar materials see Physical Anthropology in anthropology, evolution, sphr at Washington State University.
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Date Created: 03/03/15
Male Competition Because male success is dependent upon access to females not food males compete for mates in a number of ways 0 By being more attractive o By beating up the competition 0 Not all malemale competition is physical violence 0 Ex sperm competition in multimale multifemale social groups Onemale multifemale groups 0 intense competition and infanticide Males compete with each other for access to groups of females Tenure of resident males in groups is often very short 0 When males join groups they often commit infanticide kill infants lnfanticide killing infants 0 Selection favors this strategy because natural selection usually acts on individuals and on relative tness sexuallyselected male reproductive quotstrategy 0 Lactation inhibits female cycling 0 Unweaned infants death makes females available for reproduction sooner 0 Because male tenure is short 2 years infanticide enhances male s reproductive opportunities in the context of onemale multifemale groups o If infanticide is a sexuallyselected male reproductive strategy then we would predict and some empirical data observations show 0 lnfanticide will be linked to changes in male residence or status 0 Males will kill unweaned infants only o Males won t kill their own infants 0 Infanticidal males will gain reproductive bene ts from their ac ons Primate Behavioral Ecology ll Evolution of Cooperation Outline 0 Different types of social interactions 0 The problem of altruism The solutions 0 Kin selection 0 Multilevel selection 0 Reciprocal altruism Different types of social interactions 0 Strategies used during social interactions can incur costs or impart bene ts to the tness of those involved 0 GRAPH from book cases between actor and recipient with a positive or negative tness effect Sel sh improves its own tness at the detriment of someone else Mutualistic both parties cooperate to get mutual bene t Altruistic the actor does something that decreases its own bene t to do someone else a favor a Highlighted to show cooperation that we will be focusing on 0 Calling reduces relative individual tness of altruists if it increases chance of being eaten Spiteful ill go out of my way to knock you down when in turn they pay a cost as well both worse off The Problem of Altruism Presence of altruism poses an evolutionary problem Altruistic acts are costly to self and bene cial to the tness of others So how can altruistic behaviors like alarm calling evolve by natural selection And yet altruism occurs in nature 0 Alarm calls 0 Territorial defense 0 Food sharing 0 Communal care of young The Solution for Altruism How can altruism evolve how can the frequency of altruists ever increase 0 Here s the trick 0 Social interactions must be nonrandom assortative such that altruists interact with other altruists more than with non altruists o Altruistic acts must be directed at other altruists o How do primates do this Kin selection Hamilton 1964 Assumes that altruism is underwritten by genes We know close relatives share genes through common descent Altruists that selectively aid kin will tend to aid those who carry same gene for altruism creating positive assortment Hamilton s Rule Altruistic acts will be favored by selection when o rb gt c r relatedness proportion of alleles shared between altruist and recipient a the probability that 2 individual acquire the same allele due to descent from a common ancestor n r value high with parents low to non family b bene t to recipient of additional offspring resulting c cost to the altruist of fewer offspring resulting o Hamilton s rule yields predictions about altruism Altruism is restricted to kin as r0 in nonkin Higher relatedness facilitates more costly altruism Multilevel selection Wilson 1975 o Altruism may evolve in a population when groups with greater frequency of altruists outcompete groups with fewer altruists However this can only occur when variation between groups is greater than variation within groups 0 This is unlikely to be the case in most primates but see humans Reciprocal altruism Trivers 1971 o If altruists take turns giving and receiving bene ts to and from each other and not cheaters then altruism can evolve Reciprocal altruism requires Frequent opportunities to interact in different roles Ability to keep track of help given and received Only help those who provided help in past bgtc Ex grooming dyads may be examples of reciprocal altruism at work in primates 0 COO Outline 0 Important components of paleoanthropology 0 Geologic time o Geographycontinental drift 0 Paleoclimatology Taphonom y How do fossils form 0 Dating techniques How old are the fossils nishes in week 4 Paleoanthropology o The multidisciplinary pursuit seeding to reconstruct and then explain the timing and nature of evolutionary change in the morphology and behavior of our hominin relatives quotPaleoquot old 0 Geologic time scale shows age in eon era period epoch segments Geography 0 Continental drift the movement of large tectonic plates on top of denser rocks beneath o 0100mm per year Paleoclimatology Climatic conditions of the past are analyzed with oxygen isotope ratios from deepsea cores 0 Cold periods alter the ratio of 016018 found in the ocean which in turn alters the ratio in foraminifera shells 0 Shown by drilling a deep sea core Dating deepsea cores n A number of sources Sedimentation rate estimates Volcanic glass in cores can be dated with KK or KAr Paleomagnetism 0 Movement of the magnetic north pole from AD 6001900 0 The north pole moveswanders o Equatorial paci c core RC1265 graph wreversals white part Taphonomy The study of how fossils and the fossil record form F055 0 Fossilizationmineralization the process by which organic material is replaced by minerals creating a stone copy of the organic original Why are they so rare Few conditions lead to the formation of fossils a Rapid burial in ne sediment n Gentle burial n Correct chemical environment mineralrich water
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