A Taste for Blood

This week I donated blood, and as usual in that situation, I thought about vampires. (Doesn't everybody?) If vampires have razor-sharp teeth that painlessly produce tiny incisions in the skin, maybe with anesthetic in their saliva like vampire bats, they wouldn't need to leave conspicuous twin fang marks that the donor has to cover with a scarf. (Vampire bats, by the way, make incisions, not punctures.) The puncture produced by the blood donation needle, at least in my experience, is so minute that it's hardly noticeable after the bleeding stops. Usually it has almost disappeared by the next day. The procedure typically extracts a unit of blood in less than ten minutes. Afterward, the donor isn't prostrated from blood loss; the worst I ever feel is thirsty and slightly tired for a couple of hours at most. So much for the dramatic image of a victim languishing on the verge of imminent death.

That's if the vampire takes only "as much as would fill a wineglass," like Chelsea Quinn Yarbro's Count Saint-Germain. He's a supernatural vampire, though. For those creatures, we can postulate that they're really nourished more by the life-essence than by the physical components of blood, so they don't need to ingest a large volume of it. Likewise, the absurd movie scenes in which a vampire grabs a victim, bites his her or neck for a couple of minutes, and leaves a body completely drained of blood could be handwaved as magic. No awkward questions as to where all that liquid fits into the monster's body. But suppose vampires evolve naturally and have to conform to the limits of biology? As the vampire Dr. Weyland in Suzy McKee Charnas's THE VAMPIRE TAPESTRY rhetorically asks, "How would nature design a vampire?"

How do vampire bats cope with a diet high in protein and minerals but not much else, including a potentially toxic level of iron? This article explains how vampire bats' digestion and physiology have adapted to make them the only mammals able to survive entirely on blood:

Why Do Vampire Bats Have a Taste for Blood?

For one thing, they live in symbiosis with gut microbes that synthesize nutrients not found in their restricted diets. They have other fascinating adaptations for their predatory lifestyle as well, including anticoagulants as well as painkillers in their saliva and the heat-seeking ability to perceive infrared radiation marking hot spots on the bodies of their prey. We could give our naturally evolved humanoid vampires these traits. My own fictional vampires get their bulk nourishment from animal blood and milk rather than feeding heavily on human donors, whose life-energy they need to remain healthy. Still, I fudge the total amount they require with discreet handwavium. Weyland in Charnas's novel gets "good mileage per calorie," and I tacitly assume any natural vampire would have to operate that way.

Unfortunately, in real life vampire bats suffer from an inconvenient drawback as models for romantic haunters of the night. So much blood volume consists of water that the bat has to consume half its own weight to ingest enough calories to support life. Then, of course, it has to get rid of that excess liquid just to reduce its weight enough to be able to fly. Therefore, during and after feeding the bat urinates copiously. Not glamorous at all, alas. So the writer inventing a naturally evolved humanoid vampire typically avoids discussing that problem. (In THE VAMPIRE TAPESTRY, the blood-heavy bat's plight is mentioned, but that unsavory topic isn't covered in the explanation of how Weyland feeds and digests.)

I'm currently reading a Japanese novel titled IRINA THE VAMPIRE COSMONAUT, set in an alternate-world version of the 1960s space race. Members of Irina's species have fangs, rely mainly on milk for nourishment, have superhuman senses of smell but can't taste most foods, are sensitive to sunlight but not destroyed by it, lead a nocturnal lifestyle, and can endure cold better than humans but are more vulnerable to heat. They drink blood on ritual occasions but don't seem to require it for survival.

The ways authors rationalize science-fiction vampires fascinate me. Some striking examples include, besides THE VAMPIRE TAPESTRY, George R. R. Martin's FEVRE DREAM, Jacqueline Lichtenberg's THOSE OF MY BLOOD, Octavia Butler's FLEDGING, and S. M. Stirling's Shadowspawn trilogy (A TAINT IN THE BLOOD and two sequels). I analyze these and many other works in that subgenre in my nonfiction book DIFFERENT BLOOD: THE VAMPIRE AS ALIEN.

Different Blood

Margaret L. Carter

Carter's Crypt