PSY231 - Evolutionary Psychology - Chapter 1 - Introduction to Evolution PDF

PSY231 - Evolutionary Psychology Chapter 1 - Introduction to Evolution When you hear the word “evolution,” what comes to your mind? Outline 1. The origin of Natural Selection theory 2. Introduction to evolution and adaptations 3. Criticisms and advantages of Darwinian theory 4....

PSY231 - Evolutionary Psychology Chapter 1 - Introduction to Evolution When you hear the word “evolution,” what comes to your mind? Outline 1. The origin of Natural Selection theory 2. Introduction to evolution and adaptations 3. Criticisms and advantages of Darwinian theory 4. How evolutionary biology has helped to shaped modern science Important Question: Observing Zenitsu’s palpable hatred towards Tengen Uzui, we can ask ourselves: why do humans have jealousy?  Trends observed in fossil records (Jurmain et al., 2009; Trinkaus & Zimmerman, 1982; Walker, 1995). 1. Skeletons of mens contain more fracture and dents than Skeletons of women 1. Most injuries in skeletal mens skulls were located in the left frontal sides, suggesting attacks using right-hands Why do you think is this the case? Animal Biology Let’s take a look at finding from Animal Biology and Ethology. The beak of a species of bird is highly adaptive to the diets that are readily available in its environment. Why is this the case? Key Figures Pre-Darwinian Era Jean Baptiste Lamarck (1744-1829) French zoologist, naturalist, and soldier Popularized the term biologie -> The study of life as distinct science. Believed there are 2 major causes of species changes: 1) a natural tendency for each species to progress toward a higher form and 2) the inheritance of acquired characteristics. (e.g. enlarged glands, giraffe “strives” for long neck) Key Figures Pre-Darwinian Era Thomas Maltus (1766 – 1834) English scholars and economist Published An Essay on the Principle of Population in 1798 which inspired Charles Darwin to study adaptations. Posited a notion of which organisms exist in numbers far greater than they can survive and reproduce, resulting in “struggle for existence”. Favorable variations are preserved whereas unfavorable variations die out. Who is Charles Darwin? Charles Robert Darwin (1809 – 1882) English geologist and biologist. Published “On the Origin of Species” in the 1859 after returning from a 5 years voyage to Galapagos Island. Darwin sought to explain both the diversity of biological life and why is this diversity appears to be highly purposive The origin of “Natural Selection” Theory As Darwin observed and collected animals from Galapagos Islands, he postulated a theory called the Natural Selection. 1. Collected variety of finches, 2. Observed that all of the finches were actually highly different from one another. 3. Presumed that: a common ancestor of finch has now “branched off” into different species due to ecological and dietary variations. 4. The beaks adaptation must also be due to intergenerational “struggle for existence” Evolution Evolution is defined as changes over time in an organism. As postulated by Lamarck, Maltus, and Darwin, changes in life form is natural and worth to be studied. However, just saying that something changes over time does not answer the question “why did an organism change?” 3 important “ingredients” of Natural Selection A. Variation - a quality that differentiates one organism from another similar organism such as wing length, cell structure, social cunningness, trunk strength, bone mass, etc. B. Inheritance - variations must be transferable to the next generation of offspring C. Differential Reproductive Success - All of the above produced a different success rate when encountering the adaptive problem of survival.  Objections to Darwinian’s Theory of Evolution 1. No strong explanation on the mechanism of inheritance 2. Since evolution is gradual, how can a semi- evolved biological structured be useful? 3. Religious creationists object to the idea of evolution by selection. Inheritance is particulate: the role of Gene Gregor Mendel demonstrated that offspring do not receive the “blend” of both parents’ qualities but those qualities are transferred as particulate. Genes: smallest unit of heredity Genotypes: the complete sets of genes of an organism In essence, Mendel’s work supported some aspect of Darwin’s theory.  Adaptations - what are they? Evolved solutions to specific problems that contribute either directly or indirectly to successful reproduction. Selection favors a mechanism when its benefits outweigh the costs relative to other designs existent at the time (pg 19). This mechanism, overtime, becomes an Adaptation. Examples of known Adaptations: Sweat Glands - physical form Calluses - physical form Taste Preferences - psychological adaptation Mate Preferences - psychological adaptation Addressing issues of Early Stages of Adaptation Given that evolution is slow and gradual; what good is a partial eye, or partial wing? Partial forms still provide small, incremental survival and reproductive benefits. Partial wings, can aid in thermoregulation, and mobility when catching preys or avoiding other animals. Additionally, just because the benefit of an early adaptation is difficult to be conceived, it’s not a good argument against why such adaptations are developing in the first place.  But how about peacock’s plumage? Here comes Darwin’s 2nd theory which is Sexual Selection: This theory arose to explain certain observable attributes in animals that seem to not solve the problem of survival (useful for mating but carries little survival value for oneself) Advantages of Darwinian’s Evolution: 1. It explains the origin of new species 2. It explains the why some feature of an organism is highly “purposive” for a particular task 3. It connects multiple species into one grand tree of life  Clarifications on evolution - Evolutionary changes at the level of a population can also come from founder effects and genetic bottleneck - Evolution is not “intentional” and “forward-looking.” The giraffe does not “extend” its neck intergenerationally so “Gene’s Eye that the newer group of giraffe can have longer neck. Thinking” Rather, long-necked giraffes out-survived the short- neck giraffe (the opposite scenario can also be applied) and their genes get represented in the subsequent generations more. - Evolution is gradual. It can take dozen, hundreds, thousands, and even millions of generations to see changes. - Evolution can also be artificially created Artificial Selection Across numerous decades, humans seem to be able to influence the course of evolution of a species. Take dogs for instance. Dogs are direct descendant of a species of wolf known by the name of Canis Lupus. According to evolution by selection perspective, wolves who were unafraid of humans were kept and bred. “When wolves are selected for tameness, successive generations of wolves become tamer, and friendlier towards humans.” Artificial Selection This video illustrates Dmitry Belyaev’s work in artificial production of tame foxes. https://www.youtube.com/watch?v=HsIibD-TLcM Note: artificial creation relying on 1 single trait can also create other unintended changes in the subsequent generation of that organism (i.e. byproduct, such as specific color)  How do we determine an adaptation? Three standards must be invoked: Reliability: is it developed in most if not all members of the species? Economy: does the mechanism solve the adaptive problem Taste Preference for without extorting huge cost from the organism? fatty and sugary food is an adaptation that Efficiency: does the mechanism solve the adaptive problem well solves the adaptive and effectively? problem of food scarcity that beset our ancestors In short, not all mechanism can be considered an adaptation. in the previous environment. We’ll talk more about misconceptions surrounding the notion of adaptation in the following lectures. Exercise Let’s circle back to the question posited at the beginning: What function does jealousy serve? Evolutionary Theory contributions: - Ethology: Konrad Lorenz’s (1965) coined the term fixed action patterns that are observed in many species, notably in fishes and birds. - Evolutionary Psychology: Chagnon (1983) posited that Yanomami males engage in coordinated aggression against the neighboring tribes to increase access to important resources* In short, integrating findings from Biology, as well as understanding principles of Evolution, can help us gain a better understanding about human psychology.  Spicy Topics for us to learn: Why do we feel jealous? Which group of women are more likely to commit infanticide? Is there really such a thing as the expression “this lady is a tramp?” What’s the “Crazy Bastard Hypothesis?” Why do we have the capacity to be altruistic? How do bullying behaviors manifest across gender? Do men have the ability to detect which women is more fertile? What kind of qualities that can make you more attractive to member of the opposite sex? Are humans inherently monogamous creature? And many more… Summary 1. The origin of Natural Selection theory “Lamarck, Maltus, Darwin” 2. Introduction to evolution and adaptations “Evolution is changes overtime in an organism. Adaptations are evolved mechanism to a specific problem.” 3. Criticisms and advantages of Darwinian theory “Darwinian subscribes to the notion of changes overtime that are brought about by environmental inputs, Creationist object” 4. How evolutionary biology has helped to shaped modern science “Ethology is a field of biology that is inspired by evolutionary principles; modern psychology also starts to use evolutionary lens to explain human behaviors.”