Evolution’s influence on personality?

Evolutionary psychology is an approach to understanding human personality traits that I’m a little skeptical of. Evolutionary psychologists use Darwin’s discovery that an organism will develop mechanisms that facilitate its reproduction over time as justification for the view that the brain may similarly evolve in favor of traits that increase reproductive success.

One of the many topics that evo psych studies investigate is whether humans have evolved the capability to indirectly affect the sex of their offspring in order to produce offspring that will have maximal reproductive success in the environment in which they are born, known as the Trivers-Willard Hypothesis (TWH) (other animals do seem to have such a capacity). Specifically, the TWH states that when male fitness variance exceeds female fitness variance for a certain trait (i.e., when males who lack the trait have significantly less reproductive success than females who lack the trait), parents in better conditions are expected to produce more male offspring than females. Therefore, weak populations should alter their offspring ratio in favor of females, since female offspring will experience less of a reproductive setback based on their conditions than male offspring would.

Not surprisingly, findings are mixed. One study, cleverly titled “You are what your mother eats,” found, by examining food diary data from 740 pregnant British women, that mothers’ overall energy intake was positively correlated with producing male children. When the data were divided into three categories that represented the lowest, middle, and highest number of calories consumed, 56% of the women in the highest category had boys, while only 45% of the women in the lowest category did, a significant difference.

Oddly enough, the researchers also found that the amount of cereal a woman ate was also positively correlated with her chances of bearing a son. This is attributed to the fact that cereal is the most common breakfast food in the UK, so many of the women not eating cereal were not eating breakfast at all, and in turn were consuming fewer total calories than the cereal-eaters. Additionally, skipping breakfast decreases the amount of glucose in the body, so the researchers conjectured that the lower levels of glucose were interpreted by the body as overall lower resource conditions. In short, they argued that these findings demonstrate that a mother’s nutritional condition seems to be a significant predictor of her offspring’s sex.

Another study, titled “Beautiful parents have more daughters,” argues that physical attractiveness, “defined by the geometric concept of bilateral symmetry, the mathematical concept of averageness, and the biological concept of secondary sexual characteristics,” affects females’ reproductive success more than males’, since females tend to prioritize traits like stability and status for a male mate, while males prioritize attractiveness in their mates. The researchers rated parents’ attractiveness on a 5-point scale, and found that participants in the top category had significantly lower chances of bearing sons than parents in the bottom 4 categories, those who were less attractive, did. Again, they concluded that since attractiveness is a more important quality in female offspring, those parents who were highly attractive altered their offspring sex ratio in favor of females, the gender who would benefit more from the attractive phenotype.

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However, many studies fail to find evidence of the Trivers-Willard Hypothesis in offspring sex ratios. Since females use status as a criterion for male mate selection, one study predicted that parents of high socioeconomic status should be more likely to have male children, but found that this was not the case.

Because biological traits that increase individuals’ chances for reproduction are selected for, it seems logical that psychological traits may evolve in a similar way. This, in addition to the fact that humans have a propensity to draw causal relationships in almost every area of life, makes evolutionary psych very seductive. However, it is likely not a complete explanation for personality traits. One major shortcoming of this argument is that some traits that drastically reduce individuals’ chances for reproduction, such as homosexuality, remain common phenotypes. Evo psych also forces proponents to take a reductionist view of the mind, tending to reduce it directly to the sum of its parts, the physical brain. To me, it feels that context is often missing from evolutionary explanations of psychological traits, at least as far as the TWH is concerned. Could it really be possible that individual environmental traits can significantly influence a woman’s chances of bearing a son or a daughter?


Situations Matter

An excerpt from Sam Sommers’ book, Situations Matter, thanks to a recommendation by Annie Massa. A variation on one of my favorite themes: Context is everything. Can’t wait to read the full book.


A working definition of cog sci

With my college graduation just days away, it’s only natural that I’ve been doing quite a bit of introspecting: In what ways am I different from the 17-year old my parents dropped off at Vassar in 2009? How do my current beliefs and thoughts differ from those I had as I began my freshman year, and what aspects of my education have contributed to those developments? I think back to many of the classes I’ve taken over the four years: French, Latin, and Chinese, computer science, physiological psychology, the history of the English language, and anthropological linguistics come to mind. I feel that cumulatively, regardless of whether they counted towards the Cognitive Science major in the eyes of the Registrar, they have all contributed to my current understanding of the human mind.

In the fall, I’ll begin working on a PhD in cognitive science, so it seems just to expect myself to have a clear definition of the field. “It’s like psychology, right?” asks almost every curious relative, family friend, and dental hygienist I’ve encountered in the past. Others with more understanding of what cognitive science entails may see it as a lofty field, thinking about thinking, without practical applications. The conventional understanding of cognitive science, as articulated by Wikipedia, the hub of collective intelligence, is “the interdisciplinary scientific study of the mind and its processes.” While I certainly can’t disagree with this, such a pithy statement falls short for me.

The world is messy. I’ve always been tempted to impose order on it, applying logic to circumstances in which it may not belong, and I feel confident that I’m not alone in the propensity to reduce the world around me to causes and effects. However, causes and effects are meaningless in the absence of context, the world in which anything- and everything- occurs. Because this world is dynamic and constantly changing, explanatory reductions may be misguided; instead, context may be the only acceptable explanation for the perceptions and actions that we seek to understand. Cognitive science is, to me, the study of the mind- of any agent that perceives and acts in its world- that takes context as its starting point. In order to truly take context into account, the discipline necessarily draws from a number of fields, including psychology, philosophy, linguistics, anthropology, computer science and artificial intelligence, and neuroscience. Each field is simply one piece of the larger puzzle: alone, it has awkward edges and indiscernible shapes, but the amalgamation reveals a whole image that’s greater than the sum of all its parts.

On the first day of Introduction to Cognitive Science freshman year, I had no idea what cog sci was, except that “cognitive” meant something along the lines of “brain.” I created a Turing machine that could determine whether any string of x’s and y’s was a palindrome. All it needed was a set of rules, and the machine was infallible. But as soon as I added a z into the input string, it broke down completely: No Rule Defined, it told me. Because my human brain does not break down and halt in the middle of problem solving, it was evident to me that there aren’t Turing machines in our heads, but instead something else, something more complex than states and rules, that must shape how we think, sense, and act in the world.

Lessons on Chinese grammar, cultures of South American tribes, and programming a for-loop also triggered mind-related thoughts and curiosities in my foreign language, anthropology, and computer science classes. In Perception & Action, I learned more about ants than almost any human would desire to know. An ant colony is a miraculously intelligent system, another example of a product much greater than the sum of its parts. Context alone determines an individual ant’s role and how and when he will carry it out. The ant lives in a constantly changing world, but instead of causing a break down, as such a world would for a Turing machine, it encourages various behaviors that contribute to the colony’s overall success.

What does this mean for the study of human minds? It means that our perceptions, thoughts, and actions are inseparable from the contexts in which they occur. We are situated in the world, and numerous aspects of our world, like prior experiences, culture, and other people, play a prominent role in shaping what we may intuitively believe occurs only or primarily in our heads.

As I prepare to begin a new chapter in my Cognitive Science career, I expect (and hope) that my appreciation of context will color the ways in which I move forward. My devotion to the importance of context has taught me to question everything. It is important to question whether studies done under different circumstances (i.e., outside a lab) and with different subpopulations (i.e., not westernized college undergrads) may have resulted in different conclusions. It is important to question whether there may be ways of viewing the world that differ from my own view (i.e., as cyclical as opposed to linear, or correlational as opposed to causal) that may shape the research questions posed, methods employed, and findings extracted. I hope that by doing this, my mind will remain open to new possibilities, continually working toward achieving the most comprehensive understanding of the mind possible.