I have a theory, which is mine, that there is an entity or intelligence (which I will not name, since that would be unscientific) which resides in the Arctic and makes midwinter use of reindeer in a complex specified task. This theory of mine guides my research, which may not be mine, but as long as it can be interpreted to support my theory of an Arctic Artificer, I can appropriate it as mine, which is just as good.

My theory predicts that there is a peak of artificer activity in late December. The hypothesis that reindeer activity generates a polar distribution force for the delivery of artifacts generated by the Arctic Artificer is consistent with a large body of evidence. It also makes testable predictions. For example:

1. It predicts that reindeer ought to begin to spread out their levels of activity throughout the day and night in midwinter, to be better prepared to handle the complex specified task, which requires 24 hours or more of sustained activity. Reindeer activity could be monitored to test this prediction.
2. It predicts that reindeer activity should be correlated with late December deliveries of artifacts to households around the world.
3. It predicts that the polar distribution force is regulated, at least in part, by solar radiation. It might be possible to observe the incidence of solar radiation in the arctic, and to block the effects of reduced solar radiation with some really bright lights.

If the hypothesis is corroborated by these and other experimental tests, it might facilitate the delivery of artifacts, and/or the early detection of the appearance of the Arctic Artificer. Which would make my theory really important, and ha-ha-nanny-boo to those who deny the existence of an artifact production center somewhere near the North Pole.

I am pleased to report that there is a paper in the prestigious journal Nature which has evaluated my prediction A, and even though the authors had no idea that they were testing Arctic Artificer Theory, I can stretch this tenuous link to a tiny and irrelevant prediction which could also be interpreted to support many other alternatives as support for my grand theory, which is mine and reflects the glory of the Artificer, blessed be his unnamed name. (Oh, and if you can't guess what I'm talking about here, here's a clue.)

But seriously, there really are observations of circadian activity in arctic reindeer that suggest something interesting is going on in reindeer brains in midwinter and midsummer. It doesn't really support any claims of toyshops at the North Pole, but you knew that already.

Here's the real story. We exhibit circadian rhythms in many processes: sleep-wake cycles, temperature variations, hormone rhythms, blood pressure, and behavior. We have an internal clock that is ticking along at about a day, and even if you deprive us of all external cues, for instance by putting us in a cave and removing all signals from the outside world, we still cycle along rhythmically. The rhythm is the rate of our internal clocks, though, which are slightly different from the actual cycle of the sun. One way we feel this difference between what our body's clock is saying and what the world around us is saying when we experience jet lag.

Arctic animals experience an interesting natural version of the experiment of putting a person in a cave: in midwinter the sun sets and doesn't come back up for days, weeks, or months (depending on how far north you are), and likewise the sun stays above the horizon for prolonged periods of time in the summer. Animals from temperate latitudes, when deprived of solar cues, continue to exhibit a circadian rhythm, exhibiting elevated activity during the time that roughly corresponds to "day", and lowered activity during their "night". What about arctic animals?

They seem to shut off their clocks, and their activity becomes arrhythmic.

Here are some of the data to show this. It was collected the hard way, with investigators going out every day at all hours over the course of a year in the Arctic, logging all the behavior of reindeer. The white bars represent periods of alert activity, while the black bars are periods of rest. In the subspecies farther south (the left actogram), you can see a daily rhythm, mostly white during the daylight hours and black in night hours, in Fall, Spring, and Winter. In the more northerly subspecies, what you see is mostly noise (although there is a rhythm in there in Fall and Spring), indicating a lack of a regular clock.

Sample actograms showing patterns of activity over one year in sub-adult reindeer in c, northern Norway (R. t. tarandus, 70° N; n=1), and d, Svalbard (R. t. platyrhynchus, 78° N; n=1). Data, recorded continuously using small activity-loggers, are presented as double-plot actograms in which each row represents two consecutive days; time of day is indicated. Bouts of activity (black bars) are interspersed with bouts of inactivity (white spaces). Grey region, data missing. Lines indicating the beginning and end of civil twilight (when light intensity is 10 lux, orange) and sunrise and sunset (yellow) are superimposed on each actogram. Rhythmicity in the actograms was determined by F-periodogram analysis

Why would they do this? What is the advantage of abandoning rhythmic activity patterns in the long arctic day or night?

Reduced circadian organization may enhance animals' responsiveness and speed of phase adaptation to the light/dark cycle, as proposed for migrating birds and mammals emerging from hibernation. And for herbivores in polar regions, there can be little selective advantage in maintaining strong internal clocks in an effectively non-rhythmic environment.

I think what that means is that while they don't get the advantage of a prolonged period of rest, they are more rapidly responsive at all hours—unlike us, most of whom are an unresponsive and lethargic mess if we are awakened at 3AM, because our internal clocks have shut us down into a state of minimal activity.

Or, I suppose, it could be that the reindeer are just primed and on high alert, ready to answer Santa's call at any hour.

van Oort BEH, Tyler NJC, Gerkema MP, Folkow L, Blix AS, Stokkan K-A (2005) Circadian organization in reindeer. Nature 438:1095-1096.