This summer, Benjamin Zubaly is working at Dr. Jaime Palmer-Hague's social neuroendocrinology laboratory where the two researchers are seeking to clarify and demonstrate how status in humans affects the sex of offspring.
Benjamin is among the winners of TWU’s 2022 Undergraduate Student Research Awards (USRA). These awards recognize high-calibre students and support them to fully pursue their potential as researchers and scholars. Benjamin is working under the supervision of Dr. Jaime Palmer-Hague, associate professor of psychology, on the project entitled, "How Does Status Influence Offspring Sex Ratio? Dominance, Prestige, and Facial Width-to-Height Ratio."
The project aims to understand how, in humans, different forms of parental status may and may not influence the sex of offspring. As well, their project hopes to clear up many inconclusive avenues of research in evolutionary psychology.
Testing hypotheses based on the evolutionary literature
Despite existing theoretical backing for the hypothesis that status influences offspring sex, the literature exploring this topic has been inconsistent, Benjamin notes. He comments, “We believe that this inconsistency may stem from the lack of differentiation between two forms of status that have recently been explored in the evolutionary psychology literature: dominance and prestige.”
While dominance status is achieved through force or threat of force toward other individuals, prestige status is achieved through freely conferred deference by other individuals. Research suggests that dominant and prestigious individuals differ on a variety of morphological, physiological, and psychological characteristics.
If supported, their hypothesis will help the researchers to understand the phenomena of offspring sex variation better and give other researchers the opportunity to build on their findings.
Benjamin and Dr. Palmer-Hague have formulated three hypotheses that they plan to test in two studies.
Their first hypothesis is that parental dominance status influences offspring sex while parental prestige status does not. If supported, their hypothesis will help the researchers to understand the phenomena of offspring sex variation better and give other researchers the opportunity to build on their findings.
Their other two hypotheses explore associative mating—the tendency for individuals to mate other individuals with similar characteristics—based on parental dominance and whether this also has an effect on offspring sex.
Designing two focused studies on the effect of dominance status on offspring sex
The focus of their first study is on how dominance status influences offspring sex. Referring to their first hypothesis, Benjamin says, “We think that dominance may influence the sex of offspring while prestige may not, and the literature on whether status influences offspring sex may not be conclusive because only status in general has been measured, not differentiated into its two distinct forms."
To test this hypothesis, the researchers will measure dominance and prestige in parents and see whether each of these, in isolation, predicts the sex of the parents’ children.
Exploring whether associative mating influences offspring sex
The second study builds upon Dr. Palmer-Hague’s previous research by testing whether the combination of high dominance based on either trait measurements or facial ratings predicts the sex of offspring.
One study by Dr. Jaime Palmer Hague suggests that highly dominant women may increase their probability of bearing male offspring by sexually selecting highly dominant men. She found that, in mated couples, when a father was highly dominant the mother’s level of dominance was positively correlated with having a first-born son.
“There are plenty of hypotheses about why and under what conditions offspring sex will vary, but none have been unerringly supported for humans,” Benjamin observes. “By attempting to replicate and extend Dr. Palmer-Hague’s previous findings by testing our second and third hypotheses, we could open up this field for more research.”
Accordingly, their third hypothesis is that facial width-to-height ratio (fWHR) is the facial cue of dominance that highly dominant women use to sexually select highly dominant men. They will test this hypothesis by using male fWHR and female dominance to try to statistically predict the probability of having a first-born son.
Goals of advancing in the field of psychology
This fall, Benjamin is entering his third year of the BA Honours in Psychology program. As well, Benjamin is active in campus leadership. He looks forward to serving on the 2022–2023 TWU Student Association (TWUSA) team as the Social Sciences Representative.
After graduation, Benjamin plans on pursuing graduate studies in psychology, “Most likely in clinical psychology, personality psychology, evolutionary psychology, or the psychology of religion,” he said. Following his education, Benjamin hopes to pursue an academic career in psychology.
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