I was doing my usual studying thing, reading Life History of the Ache, when I had a crazy idea.
Ok, the behavior of an organism is affected by its genes and environment. This interaction, through our evolutionary past, has been acted upon by natural selection: gene-environment interactions that result in more successful reproduction than others is propagated through the gene pool until they are commonplace. That’s one train of thought.
Here is the other: Earth experiences seasons based on its axial tilt and revolution around the sun. Humans do not have a seasonal reproductive period, so babies can be born at any season. A human baby born in a certain season experiences different harmful environmental stimuli, like freezing weather, heat, predators. So, it would be beneficial if human babies had custom behaviors to maximize their own survival depending on the time they were born.
Ok, now mash those trains together (don’t worry, they’re pilotless freight trains). What if… humans have certain personality tendencies depending on the time of year they were born which were the result of genetic-environmental interaction? Or, what if some general aspect of western astrology (a yearly-repeating cycle of personality attributes) had a phylogenetic explanation?
A quick perusal of a zodiac book in my old bedroom and some internet sleuthing quickly dashed my inquiry. No study has found that astrological readings correlate with personality traits. But, if someone does explore this further and finds something significant, I wrote it down first lol.
Luna F, Alonso V, Fuster V, and Edo MA. (2008) Child age influence on the seasonal death risk during the first year of life (spain, 1975-1989). Am J Hum Biol 20:278-84.
This article finds that babies over a month old have a higher chance of dying in winter while babies under a month old have a higher chance of dying in summer. Sweet! I mean, horrible… but it supports my theory.