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For one spooky animal, vampirism is in their DNA

For millennia, the undead have run rampant through our nightmares. Zombies have ended cinematic worlds and Frankenstein’s monster has put on the ritz. But this week, the undead take to the streets—spurred on by the promise of Halloween treats. Shiny wrappers and sugar may pacify some of the beasts, but it will likely do nothing to satisfy the most bloodthirsty of them all: the vampires.

Known for their strength, intelligence, and taste for blood, vampires stand apart from other monsters and ghouls as truly formidable creatures. Bram Stoker’s 1897 novel Count Dracula set the stage for our modern image of the sophisticated vampire, but in reality, fear of vampires goes much further back in time. One of the earliest vampire stories may be that of Ambrogio, a Greek man who was cursed by the gods with eternal life and a severe sensitivity to both sunlight and silver. Showing pity on him, Artemis (the goddess of the hunt) gave Ambrogio super strength, fangs, and the ability to turn others into immortal beings—all he had to do was drink their blood1.

 

Dracula is fiction, but that doesn’t mean vampires aren’t real

It’s unclear if the myth of the vampire truly began with Ambrogio, but what is clear is that stories of werewolves, witches, and vampires have been told throughout time to help people explain what they didn’t understand. Before the advent of modern medicine, diseases like tuberculosis and rabies could sweep through entire towns, killing many along the way1,2. The mysterious spread of illness, mixed with a poor understanding of decomposition, fueled tales of monsters in the night—the undead coming back to harvest life from the living. Fortunately, stories of Count Dracula, Ambrogio, and even Grandpa Munster are all fiction. But, that doesn’t mean vampires aren’t real.

The real vampires of this world, Desmodus rotundus, live among the shadows of South and Central American caves. Thanks to their strict diet of blood, they’ve come to be known as vampire bats. As the only sanguivorous mammals (meaning they survive by consuming blood), vampire bats are particularly interesting to scientists3. Among the many questions being asked, researchers want to know how they evolved such an eclectic (and spooky) palate. Part of the answer may lay in their DNA.

Analysis of DNA from vampire bats shows that their tastes and ability to see the world have evolved with their bloody diet. An animal’s sense of taste helps them determine which foods are nutritious, and which may be poisonous. Humans can sense many different flavors, which likely helped our ancestors find the sweet, ripe fruits that were high in energy while avoiding those filled with the bitter, toxic bacteria4. Similarly, color vision helps many different types of animals discern good food from bad. The same is true for most bats, but not vampires.

 

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Did you know vampires may be helpful in medicine?

Scientists have found a potential medicine in the mouths of vampires. When a vampire bat bites livestock, it uses a protein called draculin to prevent the blood from clotting—this way it can continue to feed. Researchers are interested in draculin because it may be useful in helping dissolve dangerous blood clots in people. More research is needed to determine if draculin is suitable as a therapeutic, but it holds interesting potential.8

 

Scientists have found that changes occured in the DNA of ancestors to the vampire bat that had a large impact on their senses. Some of those changes occured in taste receptors. As a result, vampire bats have inherited a genetic profile that suggests they can’t taste most of the flavors that other bats can3,5,6. Behavioral studies reinforce this idea by showing that vampire bats likely can’t taste sweet or savory foods, and they have little response to bitter ones6. Collectively, this evidence suggests that these flavors are not so important for a vampire’s food preferences.

Other changes in DNA were passed down to vampire bats that affected their vision and heat sensation. Living mostly in dark places and without the need to pick out brightly colored fruits or insects, vampire bats have less of a need for color vision. Analysis of their DNA shows that they’re probably colorblind6. Instead, vampires rely on heat to find their meals. They’ve evolved the ability to make proteins that are particularly sensitive to heat7. These proteins can detect thermal changes from a distance and serve as an infrared tool to help them find warm blood.

Research like this has helped scientists learn about evolution, genetics, and even medicine. To be sure, the vampires of ancient lore don’t exist. But if they did, we may need more than colorful sweets to satisfy their hunger.

1History.com Editors. “Vampire History.” History.com, A&E Television Networks, 13 Sept. 2017, www.history.com/topics/folklore/vampire-history.

2Johnson, Eric Michael. “A Natural History of Vampires.” A Natural History of Vampires, Scientific American Blog Network, 31 Oct. 2011, blogs.scientificamerican.com/primate-diaries/a-natural-history-of-vampires/.

3Hong, Wei and Huabin Zhao. “Vampire bats exhibit evolutionary reduction of bitter taste receptor genes common to other bats” Proceedings. Biological sciences vol. 281,1788 (2014): 20141079.

4Bachmanov, Alexander A et al. “Genetics of taste receptors” Current pharmaceutical design vol. 20,16 (2014): 2669-83.

5Mendoza, M. Lisandra Zepeda, et al. “Hologenomic Adaptations Underlying the Evolution of Sanguivory in the Common Vampire Bat.” Nature Ecology & Evolution, vol. 2, no. 4, 2018, pp. 659–668., doi:10.1038/s41559-018-0476-8.

6Wu, Jinwei, et al. “Testing the Sensory Trade-off Hypothesis in New World Bats.” Proceedings of the Royal Society B: Biological Sciences, vol. 285, no. 1885, 2018, p. 20181523., doi:10.1098/rspb.2018.1523.

7Gracheva, Elena O et al. “Ganglion-specific splicing of TRPV1 underlies infrared sensation in vampire bats” Nature vol. 476,7358 88-91. 3 Aug. 2011, doi:10.1038/nature10245

8Low, D H, et al. “Dracula’s Children: Molecular Evolution of Vampire Bat Venom.” Journal of Proteomics., U.S. National Library of Medicine, 26 Aug. 2013, www.ncbi.nlm.nih.gov/pubmed/23748026.

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