Social Lessons from Vampire Bats
Vampire bats are accurately named, as they come out at night and drink the blood of sleeping animals. Nevertheless, they are somewhat charming, once you get to know them. In fact, the common vampire bat is one of the few animals known to share food; the others include wild dogs, hyenas, and chimpanzees.
Food sharing is a rare behavior because it would, in most cases, decrease an animal’s evolutionary fitness. Fitness describes an individual’s genetic contribution to future generations, and so it is entirely dependent on an organism’s ability to survive and reproduce. Taking care of offspring increases the parents’ fitness, but sharing food with neighbors would be more likely to reduce it. Such detrimental behavior simply would not be preserved through natural selection. But as with most things in nature, there are exceptions to the rule.
Vampire bats are one exception; sharing meals directly supports their survival and fitness. On any given night, when vampire bats go out to feed, 7-30% of them don’t manage to eat. If a bat fails to feed for two nights in a row, it will die. If a bat misses a second meal, however, a neighboring bat will regurgitate its own meal for it, keeping the hungry bat alive. The sharing bat is more vulnerable to hunger now, but it is less vulnerable than the receiving bat. And, should the first bat miss a second meal, it can expect help from another bat.
Whether or not food sharing in vampire bats is “pure altruism,” i.e., a completely selfless act, is debatable, since everybody benefits. But who cares if it is completely selfless? What could be better than a situation in which everybody benefits? This brings us to our first social lesson from vampire bats: being kind pays off. George Washington Carver put it well: “How far you go in life depends on your being tender with the young, compassionate with the aged, sympathetic with the striving and tolerant of the weak and strong. Because someday in your life you will have been all of these.”
The second lesson we can take away from the bat’s behavior is that the relative magnitude of a generous act works favorably for both parties. In the case of a starving bat, the giver helps out at some cost to itself, but the meal means life or death to the second bat. Thus, it is beneficial for members of society to share, especially when you can expect to be repaid at a later date, and especially since your help costs you so little. We make choices about how we treat each other every day. When it costs you little, but would mean the world to someone else, you have found an opportunity to be generous like a vampire bat. Take it.
For a detailed description of the vampire bat food-sharing behavior, see Wilkinson’s article at: http://facstaff.unca.edu/cnicolay/BIO379/wilkinson-foodsharing.pdf
To learn more about vampire bat feeding behavior and to read about the possible medical uses of vampire bat saliva, check out this blog post: http://thegnawblog.com/incredible-facts-about-vampire-bats/
For more information about bats and their conservation, visit Bat Conservation International’s website at: http://www.batcon.org/
Wilkinson, Gerald S. 1990. Food Sharing in Vampire Bats. Scientific American 262:2, p. 64-70.
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