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Lecture 2

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Marc A Fournier

Lecture 2: Gender, Society, and Culture (I) -Proximal determinates or accounts of human nature and individual differences: recent contextual or developmental factors that may play a role in how we come to acquire the attributes that we have. -Distal determinants: factors that have their origins in the far past and far in a way proceed our generation. Part I: The Structure of Evolutionary Theory 1. The Evolutionary Process a. Variation: people differ in their design characteristics; we are different from each other physically and psychologically b. Inheritance: Some of the differences between us are heritable. We have the ability to pass our design characteristics to our offspring. Not all design characteristics are inherited. c. Selection: the observation that not only do we differ in our design, but our design can have an impact on reproductively successful we are. The properties of our design can have effects on our rates of reproduction. - Darwin made this observation that as generations pass, some characteristics will become more common with increase of coordination and success in the environment; some design features will become increasingly prevalent as they contribute with each successive generation to the survival and reproductive success of those who have those characteristics. - You can see a pattern with changes in the environment and changes in the common features of a species as it improves their survival and reproductive success. Given a long enough time period, nearly all members of that species should come to acquire that characteristic. - Natural Selection: the evolution of adaptive characteristics because of the survival benefits bestowed on those having them.  Focus on survival. - Eg: giraffes are vegetarians and those with the longer necks survived longer and therefore the trait of long neck passed through the generations. This is called a species typical characteristic because you can characterize a species just by seeing the characteristic. - Sexual Selection: The evolution of adaptive characteristics because of the reproductive benefits bestowed on those having them. Not only do we acquire characteristics because of their survival advantages, we also acquire characteristics because of their reproductive advantages. - Intrasexual competition: competition within a given sex. Members of one sex are often in competition for preferential sexual access to members of the opposite sex (usually males competing for access to females). Those characteristics that are linked to successful competition will increase in frequency by virtue of the reproductive advantage they bestow. Those characteristics should become increasingly prevalent as they are passed on to more and more of the successive generations. - Eg: Antlers of stags have become increasingly more common throughout the generations as the ability to use antlers to compete for does increased reproductive success. - Intersexual Selection: the members of one sex come to a consensus of what is desirable in the other sex and those members of the opposite sex with those characteristics would be the desirable mates, the ones with the most reproductive advantage and are the most likely to pass on those characteristics to the next - Eg: the peahens are attracted to the peacocks plumage. 2. Products of the Evolutionary Process - Adaptation (“Evidence of Special Design”): design properties or characteristics that are selected and coordinated towards solving recurrent problems in a physical or social environment. Mostly Species-typical meaning that most or all members share that characteristic. A characteristic is adaptive because they perform some function that makes it that way. - Spandrels (“By-Products”): design properties that do not directly contribute to adaptation but are linked to an adaptive property or design and so become incidentally incorporated into the design specifications. - Eg: All humans have white bone. Therefore it is species specific. However, it is not an adaptation because it in no way helps our reproductive success. Humans need calcium and as a by-product our bones are white. The fact that our bones need calcium is probably adaptive but the property that bones are white is not. Therefore, white bones are spandrels and not adaptations. Therefore, just because something is universal doesn’t make it adaptive. - Random Effects: a final product of the evolutionary process. Design properties that are adaptively neutral – don’t make a difference between ability to reproduce or survive. - Adaptations are Species –Typical meaning they are shared characteristics between members of a species. They are also “Suspiciously” Functional meaning that they evolve with a specific function that help the species better survive in its environment. Adaptations that evolve are often economic, efficient, complex, specialized and reliable. Adaptations can be referred to as condensed records of ancestral conditions meaning the design features carry with it its ancestral history; these characteristics summarize the problems that our ancestor confronted and solved to produce the generation we have today. - There is a tendency to think that the adaptations we have today are not just good designs, but they are optimal solutions to the problems our species has confronted or we may be confronting today. This is not the case. Just because something is deemed an adaptation, does not mean that it is ideal or optimally designed. Reasons why adaptations are not optimal designs: 1. Time Lags: there is always a lag in time between the emergence of an environmental problem and the emergence of a solution in a species to solve that problem. Adaptations occur over generations. In that time, the environment can once again change causing the adaptation to be non optimal. Eg: hedge hogs which curl up into a ball when faced with a predator. This response may be ideal in their natural environment; however, it does not work very well when faced with an 18 wheeler. Therefore, an adaptation will only be adaptive today if present day circumstances are similar to historical circumstances. 2. Local Optima: as a characteristic evolves, every instantiation of that design has to be superior to the one before it. Evolution is a stubborn process, every step forward must be the step forward that leads to the biggest improvement for the reproductive success of that species. Eg: image you have to climb a mountain but you are blind folded and not allowed to use your sense. To ensure you reach the top of the mountain you use your feet and feel around and take the highest step in front of you until you think you reach the top. This could work however; you might reach to a point and think you are at the top of the mountain when in fact you are just at a local peak. You could not reach the top because your rule does not allow you to take a step down- even if you only needed to take a few steps down to reach the next peak and go up again. Evolution does not have the ability of having a generation with a poorly specified design in an effort to pursue a better design several generations later. Therefore, evolution might reach a “local peak” of evolutionary success but may not always reach the “top of the mountain.” 3. Insufficient Variation: Selection can only operate on the various designs that have already appeared within the species (as a mutation, etc.). - Just because something is adaptive or performs a specific function today, does not mean it evolved to perform that specific function. An Exaptation is a feature, now useful to an organism that did not arise as an adaptation for its present role, but was subsequently co-opted for its current function. Sometimes things that are functional today, evolved to serve a different function than they do today. Evolution loves to use old parts for new purposes. Eg: Bird’s wings were adapted for insulation. Now they are used for flight. 3. Personality as a Product of the Evolutionary Process - The Environment of Evolutionary Adaptedness (EEA) or the Pleistocene Epoch is the period of time when most evolutionists believe that most of human evolution took place. This period, from about 1.6 million years ago to about 10,000 years age, demarcates the period of the last ice age during which the ancestral conditions and selection pressures under which an adaptation evolved. - How did we as a species deal with the terrible environment during the Pleistocene Epoch? We evolved to become an incr
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