Week 4 Hunters and Gatherers
Week 4 Hunters and Gatherers ANTH 330
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This 3 page Class Notes was uploaded by Amrita Gupta on Sunday February 1, 2015. The Class Notes belongs to ANTH 330 at University of Oregon taught by Dr. Lawrence Sugiyama in Winter2015. Since its upload, it has received 71 views. For similar materials see Hunters & Gatherers in anthropology, evolution, sphr at University of Oregon.
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Date Created: 02/01/15
12615 Natural selection the differential reproduction of genes or alleles based on effect on the host Adaptation trait selected for by natural selection Behavior explanations Proximate causal explanation 0 Environmental stimuli that cause behavior like day length presence of potential mate or competitor 0 Physiological and morphological mechanisms underlying behavior like testosterone levels Ultimate functional explanation 0 Adaptive significance singing male birds attract more mates and defend their territories better than birds that don t and are favored by natural selection Ontogeny effects of the developmental environment on the behavior Learning Experience Example language development based on exposure during a critical period Phylogeny evolutionary history of the trait when did it appear in the species Historyancestry Which related species have the trait Which don t Human behavioral ecology 0 Makes explicit use of evolutionary theory 0 And of life history theory 0 Seeks to understand how natural selection shapes human strategic decision about somatic and reproductive effort 9 the larger pattern of societies Conceptual framework 0 Hominids have been faced with the challenges of foraging over the last 4 million years hunting and gathering for the last 1812 million years Phenotypic gambit 1 natural selection produces traits that on average increase the relative reproductive success of their bearers definitionobservation 2 in the process selection is likely to have produced adaptations which compel people to choose from among a range of behavioral options in ways that on average tended to increase their fitness Phenotypic gambit humans will tend to select behaviors from a range of variants whose net effect is to produce fitnessenhancing consequences 0 Given a goalset of constraints which behavioral choice would optimize or maximize fitness 0 To test hypotheses human behavior ecologists have borrowed from models from biology ecology and economics Behavioral ecology method 0 Models focus on o The behavior of individuals making decisions about 0 The available set of behavior options using 0 Some proxy currency of fitness energy time calories that permits the costs and benefits of each option to be evaluated 0 Within a set of constraints that determine the options and benefits available 0 Once a model is chosen or produced then measure actual costsbenefits of different strategies of the particular group under study to gather values to plug into model Life History Theory Evolution LHT identifies fundamental tradeoffs faced o Examining how natural selection produced adaptations yielding agerelated context dependent tradeoffs between allocation of available resources to o Measureprioritize effort for growth bodily maintenance 0 Reproductive effort I Parental effort gestation lactation feeding protection I Alloparental effort providing childcare for extended family 0 Parental investment theory examines how individuals allocate resources between 0 Different juveniles 0 Current vs future offspring 0 Quantity vs quality of offspring 0 Individuals are expected to invest differentially in different juveniles as if in response to o 1 How likely is it that the juvenile is my own offspring o 2 How likely is it that the juvenile will be able to translate investment into future reproductive success I What is the phenotypic state of the juvenile How much does it need investment I Can the juvenile get investment elsewhere or acquire resources itself 0 3 What are my alternate potential uses of this investment mating effort otherfuture offspring Juveniles are expected to be sensitive to the condition of o Themselves phenotypic condition 0 Their potential caregivers sources of investment 0 Other avenues of investment for potential caregivers 0 Their own options within a given environment Juvenile responses 0 Increase attractiveness to investors Con ict 0 Fitness interests of parentchild are different 0 Offspring increase in foraging allows parents investment in additional offspring at some cost to foraging offspring Humans have delayed maturity longer lifespan asymmetric benefit transfers 12815 Grandmother hypothesis older women provide for descendants explanation for long lifespan postmenopause 0 As humans entered a feeding niche based on difficulttoacquire foods tubers nuts 0 Juveniles could no longer support themselves efficiently 0 Mothers had to forage where weaned offspring could efficiently forage for themselves at some cost to mother 0 Foraging for richer harder to acquire resources and provisioning their weaned offspring 0 Once provisioning evolved others could enhance their fitness by provisioning genetically related juveniles o The long postreproductive lifespan of women was selected for because fitness benefits gt benefits of continued reproduction 0 Selection for grandmother effect requires that women live long enough to realize the benefits of provisioning explain relatively low mortality across lifespan Demographicadaptationist approach 0 Reproductive age function of demographic factors particularly mortality rates 0 Delayed maturation increases prereproductive mortality risk cost must be offset by fitness benefits acquired during juvenile period 0 Long juvenile lifespan is fine for skill acquisition enhances later fertilityreduced mortality 0 Social parental aggressive foraging Tooby and DeVore hominid transition to reliance on game through hunting is probably necessary for maintaining energy costs of large brains Human niche is a cognitive niche reliant on complex problem solving allowed by evolution of the vast number of dedicated cognitive adaptations Social Intelligence Hypothesis 0 Hominids achieved ecological mastery sometime around 1812 million years ago 0 Other hominids then become the most complex selection pressure 0 Social intelligence led to large brains especially dedicated to sogial cognition and complex strategic planning abilities Runaway sexual selection 0 Human intelligence as sexual signaling device 0 Kaplan et al argued that the extended juvenile period long lifespan of humans co evolved with 0 Dietary transition to highquality difficulttoacquire foods 0 Increasing investment in learning knowledgebased skills and complex subsistence strategies