Did you know that bees can perceive time? We don’t mean simple circadian rhythm stuff, like knowing when the sun is up. They can actually internally track the hours going by, which is presumably helpful when gathering pollen.
But how could we possibly know this? Well, like any science experiment, it started with a weird observation, and then scientists got curious and started guessing and testing how it works. A video on Tom Lun’s YouTube channel brilliantly tells the story of in short format, but if you don’t feel like watching a video, read on!
How to train a bee
The investigation started back in 1929, when Ingeborg Beling, a German chronobiologist (no, really, it’s an actual field!) trained honeybees to come out of their hive at a specific time of day by putting sugar water out at that time. Unfortunately her 1929 paper is behind a paywall, and also in German, but Beling’s groundbreaking work found that the bees’ memory of time (Zeitgedächtnis, if you want to really impress your friends) was quite precise and dependable, but only on a 24-hour cycle. Trying to train them to come out every 19 hours was no good, and every other day didn’t work either.
“Ah,” you may be thinking, “but that’s easy, there’s so many cues like sunshine and warmth to tell you the time!” So naturally the next step was to repeat the experiment in a dark, temperature-controlled room. Other factors eliminated were humidity, which is fairly easy to control, and air ionisation, which required using radioactive substances. Finally, O. Wahl decided to rule out cosmic radiation by repeating the experiment 180 metres below ground, in a salt mine. Even in a salt mine, the bees were dependable timekeepers.
Research intensifies
That might seem like enough proof for most people, but not for chronobiologists. They carried out more experiments, raising bees in a special incubator to try and disrupt their 24-hour rhythm, speeding up or slowing down their metabolism with chemicals, and even cooling them down to near-freezing temperatures. This last one did actually have an effect–cooling a bee down for about five hours will make them 3-6 hours late for their sugar water appointment. So I guess now we know how to embarrass a bee.
Bees get jet lag
The final piece of proof was the most convincing. Researchers reasoned that if bees were relying on external factors for their 24-hour timekeeping, those factors must be linked to the earth’s 24-hour rotational period. Changing the bees’ longitude (or time zone, as most people call it) would prove whether they were relying on external factors or their internal sense of time. Max Renner, yet another German chronobiologist, settled the matter once and for all by training some bees in Paris, then flying them on a red-eye to New York. He found that the bees were jet-lagged, searching for food at their normal Paris time. He followed it up by showing that if the experiments were done outside, the bees would gradually recover from jet lag, just like humans, using the sun to reset their internal clocks!
So, in short, we now know that bees have an internal sense of time, and also that chronobiology conferences are probably pretty wild.
Why do we care?
These studies show that bees (and insects as a whole) have better cognitive abilities than we previously thought. Bees have tiny brains – only 2 cubic millimetres, which is about 0.0002% the size of a human brain. We’re now learning that they can do more with that than we expected. Studies have suggested that time measuring could be a marker for more complex cognitive functions in the species, so now we’re interested in what else we can discover about bees.
In terms of timekeeping, we’ve learned that bees can measure short intervals of 6-36 seconds, and may even keep track of multiple different timings at once. That’s more than most humans can do!
How does it work?
The short answer is, we don’t know yet, and the bees aren’t telling. A number of potential timekeeping methods have been suggested: counting heartbeats, temperature cycles in the hive, or even simply an innate sense of time passing. It may be that the short and long timing functions depend on two different mechanisms. This area doesn’t get a huge amount of research funding, so it may be some time before scientists figure it out.
Further reading
‘Way-finding in displaced clock-shifted bees prove bees use a cognitive map’ by J.F. Cheeseman et al., P.N.A.S., 2014