Photo by Patrick Emerson*

The full moon is pregnant with foreboding interpretations, from the legendary werewolves who are supposed to transform under its malevolently shining face to a recent article about November’s upcoming full “supermoon” that faux-reassures, “despite all the rumors… there is no evidence linking supermoons to natural disasters.”

If you look at a full moon and shiver, you aren’t alone—but you are a bit of a mystery. In humanity’s past, the full moon should have been the safest time of the month, since our nocturnal predators tend to attack most on dark nights. The new moon should be spooky, as your hindbrain—unaware that you no longer live on the African savannah (unless you do!)—looks out for predators slinking in the shadows. This is presumably why the fear of darkness is such a common and instinctual one. But the full moon is bright: it should be comforting.

A paper by Packer et al. (2011) proposes a neat explanation for our nervous feelings about the full moon. They looked at African lions and their attacks on humans in Tanzania to estimate the predation pressures our ancestors might have experienced. Unsurprisingly, they found that lions catch more food on dark, moonless nights—specifically, lions have larger bellies following those nights. If lions wore belts, they would be letting them out a few notches at the new moon.

The clever distinction that Packer et al. then make is to look at when lions attack humans specifically. It turns out that lions attack humans when it’s dark, too—but also particularly in the evening. Humans tend to spend the late night in shelters, but are still out and about—and vulnerable to lions—right after sunset. The most dangerous times for humans, then, are when it is dark right after sunset: when the moon rises late. And when in the month does the moon rise late? In the days right after a full moon.

To make matters worse, lions are hungriest in the days right after the full moon, because all of those well-lit nights have been bad for hunting. They are on the prowl, and willing to try for tougher prey.

The  researchers suggest that we find the full moon spooky because it actually does bode ill. The full moon says: the next few evenings will be dark and full of hungry lions. Bad things are coming. Watch out.

Photo by M. LaBarbera

Reference:

Packer C, Swanson A, Ikanda D, Kushnir H. 2011. Fear of darkness, the full moon and the nocturnal ecology of African lions. PLoS ONE 6(7): e22285. doi:10.1371/journal.pone.0022285

(This paper is published by an open access journal, meaning anyone can read the paper for free.)

*Photos obtained from Flickr and used via Creative Commons. Many thanks to these photographers for using Creative Commons!