Lonely Ants Walk Themselves to Death
The great John Steinbeck once said that "all great and precious things are lonely." It's no wonder then, that entomologists love ants. New research has shown that loneliness may affect these creatures to a greater effect than many other living creatures.
It has long been known that loneliness, like other stressors, can lead to a shorter life. In humans, it has even been found to be a driver of high blood pressure, impaired sleep, and chronic depression that's independent from factors like age, race, gender, weight, and economic status.
However, loneliness has never been identified as a factor that can cut human lifespan by more than a small fraction of the average. The highly communal ant, on the other hand, appears to be far more sensitive to this stressor, with isolation leading to a stunning 91 percent reduction in lifespan.
That's at least according to a study recently published in the journal Behavioural Ecology and Sociobiology, which details how 'lonely' ants (as determined by how isolated they are from others of their kind) only live up to six days on average. Ants living in a crowded community, on the other hand, were found to live up to about 66 days.
The cause, researchers found, was restless pacing. In a series of experiments where ants were plucked from their colonies and isolated, loners were found to continuously walk without rest, expending far more energy then they could ever hope to regain through foraging.
This behavior could be attributed to the fact that an isolated ant is simply trying to get back to its colony at all costs, and doesn't know what to do without pheromone cues from its nest mates. After all, many entomologists would argue that an ant colony is far more a single living entity than its members. (Scroll to read on...)
If you were to take a single cog from a clock, it would simply move aimlessly as well, rotating without a purpose.
However, while there is a difference between aimlessness and loneliness, the researchers found that the latter affects isolated ants more directly.
"Isolated ants ingest as much food as their grouped nest mates, but the food is not processed fully by the digestive tract," study co-author Koto Akiko, of the University of Tokyo, recently explained to ABC Science.
The study indicated that ants can't even eat alone, as they normally collect some of the food they gather in the field in a specialized internal organ called a crop. This crop is normally shared with other ants back at a nest, but in a lone ant, it simply just sits there, undigested and useless.
Akiko's team even suggests that the sharing of that regurgitated food, a process called trophallaxis, may be a way for these morsels to become more digestible.
Alternatively, another co-author, Laurent Keller, from the University Lausanne, proposed that this social sharing of food might even serve as an important trigger for neural activity, which in turn promotes elevated gastrointestinal activity in preparation for feasting on crops.
Without that trigger, lonely ants just can't eat enough, starving as they literally walk themselves to death.
Still, it will take a lot more investigation to determine if either is actually the true cause of this morbid phenomenon.
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