I've never heard of it...
The idea isn't talked about much these days, but I can fill you in fairly quickly. Life-Force is a 1985 sci-fi horror movie directed by Tobe Hooper about aliens who dehydrate people to death, based on a Colin Wilson novel, The Space Vampires. And I'm not making this up.
Today it's a celebrated cult classic, famous for a young Patrick Stewart cameo and because the main character, played by Mathilda May, spends the whole film needlessly naked as she strolls around killing. Fun fact: the original poster had to be recalled because it featured May's nipples and the family version (below) had to be issued with lens flares painted over them. They don’t make sci-fi movies like they used to…perhaps that’s a good thing.
The movie got its title from an ancient, pre-Scientific idea called "life-force" or "vital essence" - a mysterious property all living things were believed to have. The assumption was that studying Biology was distinct from Chemistry and Physics, because living things were somehow separate to the crude matter of the inorganic world.
Supposedly, it wasn't possible to explain living phenomena without including this soul-subtance, and for centuries Biology was fused with philosophy, mysticism and magical thinking. Until Science destroyed it.
There are some hangers-on who still talk about living “energy” or “aura”, but people who trust things like clear definitions or the logic of parsimony have long abandoned the idea of life-force. Thanks to Science, we now know life isn't the result of some boring, primitive notion like magic. Life is Physics and Chemistry at their most complicated and beautiful. Here's how we figured that out in nine experimental steps.
Step 1 - Camera Obscura
The first hint that life-force might be unnecessary was uncovered by the Muslim scholar Abu Al Hasan. I’ve mentioned Al-Hasan in another blog because he essentially invented the Scientific method itself. The thing he's best known for however, is explaining how pin-hole cameras work.
If you make a tiny hole in the wall of an otherwise dark room or box, light from outside will project itself onto the far wall, creating a perfect image of the external world. This effect had been known since ancient times, but Al-Hasan successfully explained it as the geometric behaviour of light-beams moving in straight lines.
After building a number of pin-hole cameras with lenses to prove his idea, Al-Hasan got hold of a bull’s carcass and extracted its eyeball for comparison. Following a rather unpleasant dissection, Al-Hasan found that the retina of an eye behaves identically to the back wall of a camera. The pin-hole (pupil) allows light to enter and light-beams create a retinal image according to his geometric laws. There was no need of magic. Apparently you could explain the very nature of visual perception using only a basic appreciation of optics.
Step 2 - Doctor Death
Up until the 16th century, medicine was built on the work of the philosopher Hippocrates of Kos. Hippocrates never got his hands dirty with actual dissection of course, he just used intuition (guessed) and doctors learned their trade by reading his books and watching occasional amputations. It wasn’t until 1543 that a scientist named Andreas Vesalius decided to carry out genuine human autopsies and record his discoveries.
Vesalius began his career as a grave robber, unearthing bodies and dissecting them at his laboratory. This may sound immoral by today's standards, but if you want to make an omelette you’ve got to dig up a few cadavers.
Fortunately when he moved to Italy, he fell into favour with Charles V, who not only patronised Vesalius' research but began scheduling executions to match his lecture schedule so he would always have a fresh supply of corpses. Doctors of the city would be invited along and Vesalius became a morbid celebrity who would take the freshly killed criminal and cut them open as his assistants created diagrams for medical textbooks.
And, astonishingly, Vesalius began to discover that the human anatomy was not particularly different to that of animals. We had the same stuructre, the same organs and our skeletons differed only by shape and size. It would appear that ancient wisdom was wrong; humans were another breed of animal rather than a separate classification. Life-force was still part of the deal, but it was disconcerting to realise we probably shared the same life-force with dogs and cats.
This idea was heretical of course. You weren’t supposed to challenge the accepted wisdom of ancient thinkers, so it was assumed that the human body had simply changed form in the years between Hippocrates and Vesalius. The idea of throwing out an incorrect theory when contrary evidence arose wasn’t a big thing back then.
It was also Vesalius' discoveries which stirred up the first notions of ethical vegetarianism. If humans were made of meat just like every other animal, did we truly have the right to kill and eat other animals? Was it really that different from eating human meat?
Step 3 - Breathe With Me
About a hundred years after Vesalius, a physician named William Harvey dealt another blow to the ancient medical textbooks. It had long been taught that there were two kinds of blood in the human body, one manufactured in the liver, the other in the lungs.
Harvey measured the capacity of a human heart and, by timing the average pulse-rate, showed mathematically that the heart pumps 260 litres of blood per hour which would weigh three times more than the actual human. There was simply no way the liver or lungs could be manufacturing that much blood. Besides, where was it all going? Vampires?...SPACE VAMPIRES???
Harvey proposed that blood was circulated in a fixed amount, collecting something important from the heart and transferring it to the organs. Harvey’s discovery still had the idea of a life-force but in 1637 Renee Descartes (who thought therefore he was) showed that the heart was a mechanical muscle-pump and life-force was really being collected from the lungs. Apparently, blood was absorbing something we were breathing in.
It was just a matter of time before, in the 1780s, Antoine Lavoisier showed this life-force in the blood to be oxygen. He did this by collecting hundreds of guinea pigs and removing gases from their enclosures until he found the one they needed to live. Many guinea pigs died during this experiment.
Lavoisier also showed that the two types of blood were oxygenated and deoxygenated variations; there was no magical ingredient being added to blood from the lungs or heart. It was all based on Chemistry. (Lavoisier was one of the key architects of the periodic table and there's a whole chapter about him in my book Elemental...which you should definitely buy).
Step 4 - Warming to the idea
Lavoiser's commitment to Chemistry and guinea pig torture didn't stop there. He also became very interested in body heat – another mystery attributed to life-force. Lavoisier put more guinea pigs into a fiendish contraption which used their warmth to melt ice. By measuring the amount a guinea pig’s body could melt, he was able to calculate the amount of thermal energy they produced.
He then measured how much oxygen guinea pigs were taking in during the same time and burned an equal amount for comparison. He discovered that the amount of heat given off from a rodent body was identical to the amount of energy given out during a simple chemical burn. It would appear that body heat was an exothermic consequence of oxygen reacting with something in the cells of the guinea pigs.
A century and a half later, Julius Von Mayer showed that living things carry out a chemical reaction between sugars in their food and oxygen in the air. By measuring precisely the amount of sugar, oxygen, carbon dioxide, water and heat taken in or given out by a number of small creatures (presumably guinea pigs) he was able to show that the energy going into a living thing is equal to the energy coming out of it.
Energy conversation and heat laws, previously thought to apply only in the realm of Physics, were just as important in Biological systems. Apparently Biology had to obey the laws of Physics just as everything else did - it wasn't exempt or special.
Step 5 - You are all diseased
In the 1700s, the British navy was in trouble. More than 50% of its sailors were dying from scurvy; a horrible condition which causes your teeth to fall out, your skin to split open and you to die. Nobody could figure out what was going on until 1747 when the physician James Lind carried out the first medical trial in history.
Lind decided to run experiments on the crews of various ships, administering different diets to different sailors. Some were given cider to drink, some were given sulfuric acid, some vinegar, some oranges and (as a control group) some had to drink equal amounts of seawater. The results were clear: sailors who consumed oranges didn’t get scurvy.
By 1794 other foods like sauerkraut, lemons and limes were also shown to prevent scurvy and it became standard practice for ships to have a supply of citrus fruits on board (hence British sailors being nicknamed “limeys” by yanks). Finally, in the 1930s, the active ingredient preventing scurvy was identified by Norman Haworth as Vitamin-C (ascorbic acid).
It turns out that while most animals produce their own, a small number of species including monkeys, apes and bats do not make Vitamin-C. As a species, humans suffer from inherent Vitamin-C defficiency, which makes things uncomfortable for the life-force hypothesis.
If living things are bestowed with magical essence, why was it missing Vitamin-C? Why would humans and bats be born with a genetic disease while other animals get excused such a handicap? If life-force existed it was imperfect and incomplete…which sounds more like a natural, random chance thing than an ethereal, magic spirit thing. Incidentally, one other animal which lacks Vitamin-C? Guinea Pigs.
Step 6 - Back to the lab again yo...
One of the most pervasive (and ludicrous) ideas Science had to battle was the idea that there is a distinction between natural and man-made materials. This idea still hangs around unfortunately when people talk about “natural ingredients” in food as opposed to “man-made chemicals”. It’s a sophistric logic because humans are a part of nature, so anything synthesised by humans is a natural thing synthesising another natural thing...but there you go.
The first person to prove we could manufacture “life chemicals” in the lab was Friedrich Wohler in 1828. One afternoon, mostly by accident, Wohler synthesised some crystals by reacting ammonium chloride with silver nitrate and, after careful analysis, discovered them to be pure urea. Urea is a chemical found in the urine of animals and therefore impossible to make artificially...except it clearly was possible. Wohler’s discovery showed that “man-made” versions of “natural" chemicals were the same thing.
It was another Scientist named Marcellin Berthelot who took things further and threw life-force into serious turmoil. Following in Wohler’s footsteps, Berthelot decided to catalogue and synthesise every known “biological chemical” he could think of using inorganic lab ingredients. He managed to create ethanol (yeast excrement), methanoic acid (ant blood), benzene (found in Styrax bark) and began advocating the idea that living things were complex arrangements of molecules. You could, in principle, create any substance found in a living thing if you knew how to arrange the atoms.
By the mid twentieth century we had figured out the atomic compositions of thousands of biological substances. Max Perutz solved the structure of Myoglobin and Haemoglobin, Linus Pauling solved the protein alpha-helix, Franklin, Watson and Crick solved the structure of DNA and the undoubted queen of Biochemstry, Dorothy Hodgkin, successfully figured out steroids, penicillin, Vitamin B12 and Insulin (a molecule of 777 atoms, getting her the most hard-earned Nobel Prize in Biology).
There was no life-force needed to account for any of it. If you were careful you could glue atoms together in the right order and make any living thing you wanted. In other words: nature isn't adding anything to life, it's just arranging atoms in phenomenally complex ways.
Step 7 - It's alive! It's aliiiive!
In the 1790s, Luigi Galvani was dissecting frogs in his lab. Most of his experiments concerned electricity, so his laboratory was filled with electrical equipment and by chance, a metal scalpel which had built up a charge came into contact with the sciatic nerve of an amputated frog leg, causing it to twitch. Galvani's curiosity was galvanised. Sue me.
He began conducting (pun intended) other experiments like wiring frog corpses to his electricity machines or fixing them to metal rods during thunderstorms and discovered that motor neurons are wires carrying small currents. Whereas life-force suggested movement was the result of a spirit inside your body pulling strings, Galvani showed that movement is the result of electrifying muscle tissue and could be carried out on dead muscle just as easily as live.
Allessandro Volta took things further and showed that the electrical currents in neurons were identical to those generated by batteries and finally, in 1865, Julius Bernstein proved that chemical reactions in cells are capable of generating the tiny voltages Galvani had discovered. Once again, a mysterious bio-property could be explained in terms of Physics and Chemistry.
It has been speculated that the discoveries of Galvani and Volta influenced Mary Shelley’s 1818 novel Frankenstein in which a hubristic Scientist attempts to reanimate human tissue. Sadly, this original version was heavily rewritten into the far more famous, "audience-friendly" version of 1831, removing a lot of the satire...and presumably painting lens flares over Frankenstein's nipples! Frankenstein was one of my favourite novels as a teenager and arguably the first work of modern Science Fiction. If you decide to read it, I recommend Shelley’s original 1818 text. It's got more bite.
Step 8 - It's dead, it's deeaaad!!!
In 1896, Eduard Buchner (shown below) was interested in fermentation. If you feed sugar to a bunch of yeast cells, they crap out ethanol and carbon dioxide. By now, life-force was in serious question and the Scientific community was divided on whether fermentation was a biological or chemical process. Some assumed yeast cells were converting sugar to ethanol via life-force means (aka hocus pocus) while there was a growing feeling that yeast cells contained a chemical which reacted with sugar.
The distinction between biological and chemical processes was, of course, a false dichotomy which Buchner proved in a blindingly obvious yet brilliant experiment. He tried to achieve fermentation with dead yeast.
If Biology was basically Chemistry, then structurally there should be no difference between a living cell and a dead one, so if you killed the cells and burst them open, their chemical guts should be unchanged. Lo and behold, Buchner successfully achieved fermentation with dead yeast cells, proving that living stuff could carry out the same processes as dead stuff.
Step 9 - Soup's Up!
By the 1950s Darwin’s theory of natural selection was so well-evidenced, it was accepted that life on Earth originated from a common ancestor billions of years ago. The only question was how that life got there in the first place.
It was one thing to say living things are today the result of biochemistry, but the initial spark which gave rise to proteins, enzymes and information chains was still unexplained. It was sometimes nicknamed “Darwin’s Black Box” because nobody could figure out how to get life from a sterile Earth. So naturally people plugged life-force into the epistemological gap.
But then, in 1953, Harold Urey and Stanley Miller decided to replicate the conditions which had birthed Biology. By stewing all the chemicals known to exist on Earth at the time (easily learned from studying rocks, ice cores and cosmic nebulae), they filled a flask with methane, ammonia, hydrogen, water and began spark-plugging this "primordial soup" to simulate lightning.
After a week the soup had changed composition entirely. It was filled with amino acids, the building blocks of proteins and enzymes. If it was possible for lifeless chemicals to synthesise amino acids in a few days, imagine what could be achieved in a few hundred million years with a churning ocean, lightning, hydrothermal vents, rock pools, ultra-violet rays and so on.
(NB: some people have mistakenly criticised the experiment because along the road to making amino acids, the Miller-Urey experiment also made cyanide and formaldehyde, which are obviously poisonous, leading to fallacious rejection of the results. What's not being understood by these people is that the cyanide and formaldehyde are part of the sterile mixture of chemicals...if you react them long enough they do make amino acids, that's the whole point of the experiment.)
The final “missing link” between these amino acids and simple proteins has not yet been discovered, however. We’ve figured out step 1 of the life process, and we know steps 4,5,6,7... etc, but we’re missing a few steps in between. It is here that the remaining spiritualists and witches set up camp, insisting life-force must exist within those few question marks left in the chain.
As a Scientist, I have to concede that they may be right. However, I think it’s unhealthy to cling to an un-evidenced hypothesis. Furthermore, the history of Biology has shown that the more we’ve studied it, the smaller life-force’s reach has become.
It makes sense that early explanations for living things would favour magic over testable laws of Science...nobody knew any testable laws of Science! But now that our knowledge has matured, I think we can safely shrug off the cloak of mysticism. We cannot know with certainty of course, but wisdom suggests that life-force has been truly sucked dry.
Soul leaving body: YouTube
Life-Force poster: thecultmoviereview
Look into my eye: giphy
Hannibal Lecter: wikipedia
Shameless Plug: shamelessplug7
Guinea Pig 1: imgflip
Guinea Pig 2: angryapps
Dorothy Hodgkin: thefamouspeople
Pain in the ass frog: knowyourmeme
Primordial Soup: defendingthebible
I love science, let me tell you why.