Groundhog Day, Correlation, and Human Evolution

Minds designed for pattern recognition.

Posted Feb 02, 2017

Skeeze / Pixabay
Source: Skeeze / Pixabay

Do you think that Punxsutawney Phil actually determines the timing of the coming of spring? Preposterous! Few holidays rival Groundhog Day in silliness. Perhaps evolutionary psychology can help us understand what is going on here.

The human mind has many biases—including the basic tendency to see patterns in pretty much anything (Chambon, 2007). We tend to see correlations among all kinds of things, regardless of whether there is any empirical basis for seeing such patterns (Mullen & Johnson, 1990).

Before the large-scale advent of evolutionary psychology, social psychologists generally framed these kinds of psychological biases in terms of how ridiculous the human mind can be. The evolutionary psychological perspective (Geher, 2014), however, sheds unique light on why we are the pattern-seeking ape.

Minds Shaped to Process Correlation

Under ancestral conditions, humans did not have many of the awesome technologies that we have now. Ancestrally modern humans didn’t have weather apps for their phones (or phones), but they came to associate dark clouds on the western horizon as indicative of lightning storms coming their way. They didn’t keep track of birthdays via Google Calendar, but they responded differentially to infants, toddlers, teens, and elders based on physical and behavioral characteristics, such as the presence or absence of wrinkles, that were correlated with age.

In statistical terms, we talk about a significant pattern or relationship between two variables as a correlation (). And these days, we have some pretty sophisticated mathematical and computer-based processes for computing and discussing correlations among variables. Our pre-agrarian ancestors did not know how to compute a Pearson r coefficient, but their minds were shaped to have an implicit understanding of correlation nonetheless. This is because having an implicit understanding of variables that naturally correlate with one another was simply adaptive for our ancestors.

Groundhogs and the Coming of Spring

I live in upstate New York, and each year I spend countless hours cultivating my vegetable garden. I am pretty sensitive to the presence of groundhogs—with good reason. Groundhogs are enemy sine qua non when it comes to vegetable gardens here. I have seen them take out entire batches of cucumbers, pumpkins, lettuce, and more! Groundhogs are relentless, and the fences around the gardens in my part of the world are designed to keep these critters out.

Now, all this business about the groundhog “seeing its shadow” and the timing of the coming of spring, of course, contains a lot of nonsense. Then again, the presence of groundhogs in February in much of the world may well be telling.

Here it is, February 2, 2017, and the ground throughout Ulster County, New York is covered in frozen snow. I haven’t seen a groundhog poking around for months. If I saw a groundhog today, that’d be a sign of an unseasonably warm spell in upstate New York. And a warm spell in early February is likely predictive of a relatively short winter on average. In other words, temperatures in early February are correlated with the overall length of the winter season.

Bottom Line

Mark Van Scyoc/Shutterstock
Source: Mark Van Scyoc/Shutterstock

On the surface, Groundhog Day may seem like the silliest holiday. But when you apply an evolutionary framework for understanding it, the day actually makes some sense. The human mind evolved to see patterns in nature: Effective pattern-detection gave ancestral hominids a leg up in survival and reproduction. If you see a groundhog prancing around in early February, odds are that a relatively mild winter is upon us. And if that’s true, you'd better start planning your vegetable garden early, and you'd better start thinking about the barrier that you will build to keep out the groundhogs, rabbits, chipmunks, deer, and all other foes during the upcoming growing season.

Happy Groundhog Day from Darwin’s Subterranean World!


Chambon, Valérian; et al. (2007). "Visual Pattern Recognition: What Makes Faces so Special?". In Corrigan, Marsha S. Pattern Recognition in Biology. New York: Nova Science Publishers.

Geher, G. (2014). Evolutionary Psychology 101. New York: Springer.

Geher, G., & Hall, S. (2014). Straightforward Statistics: Understanding the Tools of Research. New York: Oxford University Press.

Mullen, Brian; Johnson, Craig (1990). "Distinctiveness-based illusory correlations and stereotyping: A meta-analytic integration". British Journal of Social Psychology. Wiley-Blackwell on behalf of the British Psychological Society. 29 (1): 11–28.