By Dov Michaeli

So here we are in Romania, a country we knew hardly anything about. We came to hike in the Carpathian mountains, preparing ourselves to ten days of masochistic pleasure, climbing steep mountains. We were pleasantly disappointed; no grueling hike, but instead incredible views of bucolic countryside straight out of a Pieter Bruegel painting, with farmers harvesting hay for their livestock with a sickle. 

Or a wizened peasant woman collecting the hay into a big mound with a rake, straight out of a Millet painting.

You’d think this world vanished a long time ago. But there it is, alive and well.

How could they survive in the modern world? Better than you’d think. Iulian, our wonderful guide (http://www.mountainguide.ro/romanian-mountain-guides/) assured us that unlike us “modern” consumers, their culture does not countenance debt: you buy only when you have the cash to pay. All those wonderfully painted and lovingly maintained farmhouses are fully paid for. Hence, the financial debacle of the West barely touched them. And hence the sense that these people are genuinely happy with their lot. So where did we go wrong? As Tom Friedman points out today (NYT, 28 August, 2011), we will have to re-think our system of consumption-and-debt-based capitalism. The Romanian peasant shows us that one can be happy without incurring debts, that modernism is not necessarily progress.

But I am digressing. I know you want to know about Dracula. Well, the story is partly disappointing, and partly fascinating.

The myth

Vlad The Impaler

Bram Stoker’s Dracula is fictional, plain and simple. It is based on a Romanian prince of the 15th century, Vlad the impaler.
Why this terrible appellation? Because to quell the social unrest in the area under his rule he impaled his enemies. Sounds pretty horrible, except that cruelty was the modus operandi of those days. Just consider the Inquisition and what it did in the name of God. At least Vlad didn’t pretend to divine blessing of his methods. As to impaling, 1000 years before Vlad the Assyrian king Sennaherib was a master of the art, and left many inscriptions vividly depicting his impaled victims. But who would buy a book based on somebody called Sennaherib the impaler? Stoker’s choice was shrewd, but largely fictional. Even the castle in the village of Bran wasn’t really Vlad’s. He possibly spent a few days there, but it actually belonged the 19th century Romanian queen Mary, a highly cultured author of novels, and not at all bloodthirsty.

So what’s the fascinating part of the Dracula story?

The science of vampires

I am not talking about the fictional vampires, sucking the life out of their victims, turning them into non-dead, or what we call today the walking dead; in a word, zombies. I am referring to real vampires, of the bat species. There, on the mountains of Transylvania, was the appropriate place to ponder the question: how do the vampire bats home in on the blood vessels? After all, they are blind as a… bat.

Regular bats are known to find their food, be it fruit or insects, by echolocation. They emit sounds and listen to the sound waves bouncing back. That’s exactly how radar works. But blood vessels don’t return sound waves any differently from any other tissue. And, let’s not forget –they are located under the skin, so they are not accessible to sound waves anyway. But, they do have a unique characteristic: they make the skin overlaying them warmer. And the vampire bat can sense that heat.

Let’s stop and think for a second. Beyond the straightforward biological fact there is something more deeply philosophical here. We, as many other animals, see the world in colors. But this is not the only way to see the world. Echolocating bats see the world in sounds, and heat-sensing bats (and by the way, also pit viper snakes) map the world in their brain as a heat map. Is any way to look at the world superior to the other? Just consider: can we hit a flying insect with the accuracy of a bat? Or home in on an object with the speed and accuracy of a vampire bat? No, we are not superior -we are just different.

How they do it is the subject of a recent paper (Nature, August 1, 2011). We, and all other animals, have receptors that sense heat. They are called TRPV1, and are essential to survival; without them we would be scalded and burned without sensing it. Here is a fascinating side story: these very same receptors sense also a chemical called capsaicin, which is a component of chili peppers. Is it any wonder that we characterize spicy food as being hot?

What does all this have to do with vampire bats? Well, nature never ceases to amaze. Those bats have a truncated (shortened) version of TRPV1. The short version made by vampire bats has a lower heat threshold, so that it can detect substances—like blood—that are at body temperature. Truncated TRPV1 appears in only nerves that innervate the small heat sensing pits on the bat’s face. Other nerves have the longer, pain-sensing version. How did it work in evolutionary terms? The first bat with the truncated receptor mutation sensed heat, and homed in to the source, which happened to be a great source of nutritious blood. This lucky bat had an obvious survival advantage –blood beats flowers or insects as a source of food. The need for echolocation disappeared, and thus we end up with a vampire bat.

Now, I know you think these creatures are repulsive. Would it help if I told you that bats are not really related to rodents? The DNA sequence of TRPV1, the heat sensor, confirms the recent evidence that bats are related, believe it or not, to moles, cows and horses. So think of this creature as a lovable flying cow or horse and you may get over your aversion to the blood sucking bats and Dracula’s mythical vampires.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.