How math predicts life on Earth and the universe beyond
Math doesn't suck. It is one of humanity's greatest and most mysterious journeys.
MICHELLE THALLER: Mathematics is in some ways kind of scary in how useful it is at really describing how the universe works around us. Now, I mean to give you an idea, the origin of mathematics seems very straightforward. We can count on our fingers up to ten and maybe it was useful to understand how many sheep you had so you could start counting sheep. And then you either added or subtracted sheep as you got more or as you lost some. It was a simple thing. We learned how to count. We learned how to add and subtract. The idea of multiplying and dividing is a little more abstract but that also makes sense. That's something that we can kind of visualize. But then what amazes me is that this led us on a tremendously complicated journey that's still going on to this day and we had no idea where this would lead us.
EDWARD FRENKEL: It's a very unfortunate situation when you can't even begin a conversation about mathematics without people saying 'Oh, my gosh. I don't want to talk about it.' And it's kind of strange because no one would ever say 'I hate literature' or 'I hate art' or 'I hate music.' At least, intelligent people would never say that. It's kind of shameful to say that. But it's perfectly okay in our society to say 'I hate mathematics.' And so what I dream of is a society in which it's not that everyone has a Ph.D. in mathematics, but rather I would like to live in a society in which if mathematics is brought up someone would say 'Oh, mathematics. Interesting. How do I find out more? Can you give me a gist of the idea?' I'm not scared of it. I'm curious about it, the way I'm curious about the solar system, about the atoms and the DNA. All these things which are in our collective consciousness, in our public discourse, which are no simpler than mathematical concepts. Mathematical concepts are no more complicated than these concepts in physics and biology that are in the air, that are what we are aware of. So I would like people to be aware of this, of these mathematical ideas. I'd like them to be more and more aware of how mathematics invades our lives. How it's controlling our lives.
MICHIO KAKU: In the 1600s, Isaac Newton asked a simple question: If an apple falls, then does the Moon also fall? That is perhaps one of the greatest questions ever asked by a member of homo sapiens since the six million years since we parted ways with the apes. If an apple falls, does the Moon also fall? Isaac Newton said yes, the Moon falls because of the inverse square law, so does an apple. He had a unified theory of the heavens, but he didn't have the mathematics to solve the falling Moon problem. So what did he do? He invented calculus. So calculus is a direct consequence of solving the falling moon problem.
PO-SHEN LOH: I do think that everyone in America could benefit from having that mathematical background in reasoning just to help everyone make very good decisions. And here I'm distinguishing already between math as people usually conceive of it and decision making and analysis which is actually what I think math is. So, for example, I don't think that being a math person means that you can recite the formulas between sins, cosines, tangents and to use logarithms and exponentials interchangeably. That's not necessarily what I think everyone should try to concentrate to understand. The main things to concentrate to understand are the mathematical principles of reasoning.
FRENKEL: And I understand why people are scared and frightened. It's not their fault. It's because of how mathematics is taught in our schools.
LOH: I think that actually one reason mathematics is difficult to understand is actually because of that network of prerequisites. You see, math is one of these strange subjects for which the concepts are chained in sequences of dependencies. When you have long chains there are very few starting points. In mathematics you have very few that you memorize and the rest you deduce as you go through. And this chain of deductions is actually what's critical. Now, let me contrast that with other subjects like say history. History doesn't have this long chain. In fact, if you fully understand the War of 1812 that's great and it is true that that will influence perhaps your understanding later of the Women's Movement, but it won't be as absolutely prerequisite. In the sense that if you think about the concepts, I actually think that history has more concepts than mathematics, it's just that they're spread out broader and they don't depend on each other as strongly. Math has fewer concepts but they're chained deeper. And because of the way that we usually learn, when you have deep chains it's very fragile because you lose any one link meaning if you miss a few concepts along the chain you can actually be completely lost. Now, I think that the way to help to address this is to provide a way for everyone to learn at their own pace and, in fact, to fill in the holes whenever they are sensed. I actually feel like if everyone was able to pick up every one of those prerequisites as necessary filling in any gap they have, mathematics would change from being the hardest subject to the easiest subject. So after thinking for some time I actually came to an idea which was based on using these core mathematical areas that I had been working with to actually build a solution for education that could be delivered for free on every smartphone. This is actually the project that I'm working on right now called Expii. Our principle is that actually you could turn that smartphone into a virtual tutor which automates what a person would get if they hired a tutor. It's not that the class comes first and then the homework and then the exam. The first thing that comes is the exam essentially followed by these practice problems which adapt to you, followed by the class for anything that you don't know. The idea is that this should cure boredom at the high end and also cure confusion at the struggling end.
KAKU: Some people ask the question of what good is math? What is the relationship between math and physics? Well, sometimes math leads, sometimes physics leads, sometimes they come together because, of course, there's a use for the mathematics.
JANNA LEVIN: As a theoretical physicist I rely very much on calculating to understand results. So let's say I want to know what happens when a big black hole swallows a little tiny black hole. My starting point will be to think what's my first mathematical sentence that I know if I crack it open will answer this question? Now even that step can be very hard. And then once I do that I'll be moving in a very structured way through the steps to unlock that. When I work with much younger students I like to kind of sit back in the room when we're calculating now and ask them to try to find the solution in the way that we do know how to go one step after another, but I'll be trying at the same time to try to find that cute way of unpacking it that's highly non-obvious. And sometimes I'm sitting there for two days while they're generating 12 pages of very tough, beautifully done calculations where I'm trying to find a way to try to do it in a half a page. And sometimes I succeed and sometimes I don't. Sometimes I can't do that. It's just not possible or I haven't figured out how to do it. And sometimes I do. And when you do it's not just that it's shorter, it's that you're working with such bigger structures that you can see so much more at a time.
KAKU: Then here comes Einstein asking a different question and that is: What is the nature in origin of gravity? Einstein said that gravity is nothing but the byproduct of curved space. So, why am I sitting in this chair? A normal person would say I'm sitting in this chair because gravity pulls me to the ground. But Einstein said no, no, no, no. There's no such thing as gravitational pull. The earth has curved this space over my head and around my body so space is pushing me into my chair. So to summarize Einstein's theory: Gravity does not pull. Space pushes. But, you see, the pushing of the fabric of space and time requires differential calculus. That is the language of curved surfaces, differential calculus, which you learn in fourth-year calculus. So again, here's a situation where math and physics were very closely combined but this time math came first. The theory of curved surfaces came first. Einstein took that theory of curved surfaces and then imported it into physics.
THALLER: If you can do multiplication and subtraction it's not too long before you begin to develop the basic building blocks of calculus. And calculus describes how moving objects can change, how things can accelerate. If you want to describe an apple falling from a tree to the ground or a ball rolling down a hill, that's calculus. It's the mathematics of how things can change over time. That's really interesting and the amazing thing is it works so well. If you use these equations to predict how a ball will roll down a hill, reality matches that. It really does tell you how something is going to behave. So now we've gone from counting on our fingers how many sheep we have to being able to predict what the universe around us is going to do. That's incredibly powerful.
GEOFFREY WEST: Just taking mammals, that the largest mammal, the whale, is in terms of measurable quantities, that is of its physiology and its life history, is actually a scaled-up version of the smallest mammal which is actually the shrew but a mouse is very close to that and everything in between, but they are scaled versions of one another. The most well-known of these is the scaling of metabolic rate and metabolic rate is maybe the most fundamental quantity of life because metabolic rate simply means how much energy or maybe just how much food does an animal need to eat each day in order to stay alive. And everybody's used to that and is familiar with that, it's sort of roughly 2,000 food calories a day for a human being. So you can ask what is that for different mammals? And what you find is that they're related to one another in a very simple way despite the fact that metabolism may be the most complex physical chemical process in the universe, for all we know. It's phenomenal, because metabolism is taking essentially something that's inorganic and making it into life. So here's this extraordinary, complex process and yet it scales in a very simple way and you can express it in English—you can express it quite precisely in a very simple mathematical equation—but in English, it's roughly speaking that every time you double the size of an organism from say two grams to four grams or from 20 grams to 40 grams or 20 kilograms to 40 kilograms or whatever, just doubling anywhere, instead of what you might naively expect, double the size, double the number of cells, roughly speaking, therefore you would expect to double the amount of energy, the amount of metabolic energy you need to keep that organism alive because you have twice as many cells. Quite the contrary, you don't need twice as much. Systematically, you only need, roughly speaking, 75 percent as much. So there's this kind of systematic 25 percent, one-quarter, savings. And it turns out that anything else you measure, as I mentioned a moment ago, scales in a similar way with this sort of 25 percent rule occurring in some interesting way. The same mathematical—and this is extremely important—the same mathematical and physical principles apply to a mammal, which has a beating heart, as applies to a tree. And a mammal, our circuitry system is a bunch of tubes like in your house, the plumbing in this building we're sitting in, that's our circulatory system. But a tree and a plant, they're not like that. They're a bunch of fiber bundles kind of joined together like electrical cables that spray out and that's what you see when you see a tree. But even though they—and they don't have beating hearts, as we well know. And yet they satisfy the same mathematical principles and those mathematical principles give rise to this quarter-power scaling in mammals, but also in plants and trees, but also in fish and birds and crustacea, in principle, and insects and so on, and that's the idea.
THALLER: Now we look around us and we see things like planets orbiting the stars or the galaxy turning around and we realize those equations of motion apply to everything else in the universe. It's not just here. It's not just on the surface of the earth, but we can look at things literally billions of lightyears out in space and they're following those same rules of mathematics. So we keep getting led farther and farther down this rabbit hole. Where does math lead us? Now we realize that you can describe physics incredibly well if you allow the universe to exist in many different dimensions, more than the three dimensions that we're familiar with. In fact, specifically if you want to do particle physics it requires 11 dimensions. That's not something our minds comprehend but we can do the math. We can do the math of how things would behave if they could move in 11 different directions. And it turns out to predict exactly the results we get from particle physics. That's kind of scary. Does that mean that's real? Are there really 11 dimensions? The math works so well and the predictions are so strong that it can't just be nonsense. But now we've gone to the limit of what I can tell you: Is it real or not? Our math has given us something incredibly useful, but it's taken us completely out of our realm of common sense, of human scale, of how our minds work and even our sense of space and time. I don't think that journey's over yet. Where is math going to lead us? It may lead us to understand things like the universe is a type of a hologram. That was a mathematical solution to how things work around a black hole and it works really, really well. So, I think it's wonderful and a little bit scary that you start counting on your fingers, you get to 11 dimensions of space and time and where else?
- There is a pervasive cultural attitude against mathematics, but it is actually a mind-blowing tool for analyzing and predicting the world around us—and far beyond. We asked mathematicians Edward Frenkel and Po-Shen Loh, and physicists Michio Kaku, Michelle Thaller, Janna Levin and Geoffrey West to explain the wonders of math.
- West explains the rule of 'quarter-power scaling' in biology—there is a mathematical equation that predicts how much food an organism needs to eat to survive and it's remarkably consistent, whether you're looking at ladybugs, cats, elephants, and even trees and flowers. Math underpins our lives in incredible ways.
- Infinitesimal calculus—the math that describes how moving bodies change over time—turns out to predict not just phenomena on Earth but far out in the universe. The 11-dimensional math used by physicists turns out to predict the exact results of particle physics experiments. Humanity is on an incredible journey with mathematics and every day it opens up the world and universe in eye-opening ways.
- Plato on what makes us tick & why math matters so much - Big Think ›
- 10 great physics courses you can take online right now, for free - Big ... ›
- There are 2 dimensions of time, theoretical physicist states - Big Think ›
- Physicists puzzled by strange numbers that could explain reality ›
Once a week.
Subscribe to our weekly newsletter.
She helped create CRISPR, a gene-editing technology that is changing the way we treat genetic diseases and even how we produce food.
This article was originally published on our sister site, Freethink.
Last year, Jennifer Doudna and Emmanuelle Charpentier became the first all-woman team to win the Nobel Prize in Chemistry for their work developing CRISPR-Cas9, the gene-editing technology. The technology was invented in 2012 — and nine years later, it's truly revolutionizing how we treat genetic diseases and even how we produce food.
CRISPR allows scientists to alter DNA by using proteins that are naturally found in bacteria. They use these proteins, called Cas9, to naturally fend off viruses, destroying the virus' DNA and cutting it out of their genes. CRISPR allows scientists to co-opt this function, redirecting the proteins toward disease-causing mutations in our DNA.
So far, gene-editing technology is showing promise in treating sickle cell disease and genetic blindness — and it could eventually be used to treat all sorts of genetic diseases, from cancer to Huntington's Disease.
The biotech revolution is just getting started — and CRISPR is leading the charge. We talked with Doudna about what we can expect from genetic engineering in the future.
This interview has been lightly edited and condensed for clarity.
Freethink: You've said that your journey to becoming a scientist had humble beginnings — in your teenage bedroom when you discovered The Double Helix by Jim Watson. Back then, there weren't a lot of women scientists — what was your breakthrough moment in realizing you could pursue this as a career?
Dr. Jennifer Doudna: There is a moment that I often think back to from high school in Hilo, Hawaii, when I first heard the word "biochemistry." A researcher from the UH Cancer Center on Oahu came and gave a talk on her work studying cancer cells.
I didn't understand much of her talk, but it still made a huge impact on me. You didn't see professional women scientists in popular culture at the time, and it really opened my eyes to new possibilities. She was very impressive.
I remember thinking right then that I wanted to do what she does, and that's what set me off on the journey that became my career in science.
CRISPR 101: Curing Sickle Cell, Growing Organs, Mosquito Makeovers | Jennifer Doudna | Big Think www.youtube.com
Freethink: The term "CRISPR" is everywhere in the media these days but it's a really complicated tool to describe. What is the one thing that you wish people understood about CRISPR that they usually get wrong?
Dr. Jennifer Doudna: People should know that CRISPR technology has revolutionized scientific research and will make a positive difference to their lives.
Researchers are gaining incredible new understanding of the nature of disease, evolution, and are developing CRISPR-based strategies to tackle our greatest health, food, and sustainability challenges.
Freethink: You previously wrote in Wired that this year, 2021, is going to be a big year for CRISPR. What exciting new developments should we be on the lookout for?
Dr. Jennifer Doudna: Before the COVID-19 pandemic, there were multiple teams around the world, including my lab and colleagues at the Innovative Genomics Institute, working on developing CRISPR-based diagnostics.
"Traits that we could select for using traditional breeding methods, that might take decades, we can now engineer precisely in a much shorter time."
DR. JENNIFER DOUDNA
When the pandemic hit, we pivoted our work to focus these tools on SARS-CoV-2. The benefit of these new diagnostics is that they're fast, cheap, can be done anywhere without the need for a lab, and they can be quickly modified to detect different pathogens. I'm excited about the future of diagnostics, and not just for pandemics.
We'll also be seeing more CRISPR applications in agriculture to help combat hunger, reduce the need for toxic pesticides and fertilizers, fight plant diseases and help crops adapt to a changing climate.
Traits that we could select for using traditional breeding methods, that might take decades, we can now engineer precisely in a much shorter time.
Freethink: Curing genetic diseases isn't a pipedream anymore, but there are still some hurdles to cross before we're able to say for certain that we can do this. What are those hurdles and how close do you think we are to crossing them?
Dr. Jennifer Doudna: There are people today, like Victoria Gray, who have been successfully treated for sickle cell disease. This is just the tip of the iceberg.
There are absolutely still many hurdles. We don't currently have ways to deliver genome-editing enzymes to all types of tissues, but delivery is a hot area of research for this very reason.
We also need to continue improving on the first wave of CRISPR therapies, as well as making them more affordable and accessible.
Freethink: Another big challenge is making this technology widely available to everyone and not just the really wealthy. You've previously said that this challenge starts with the scientists.
Dr. Jennifer Doudna: A sickle cell disease cure that is 100 percent effective but can't be accessed by most of the people in need is not really a full cure.
This is one of the insights that led me to found the Innovative Genomics Institute back in 2014. It's not enough to develop a therapy, prove that it works, and move on. You have to develop a therapy that actually meets the real-world need.
Too often, scientists don't fully incorporate issues of equity and accessibility into their research, and the incentives of the pharmaceutical industry tend to run in the opposite direction. If the world needs affordable therapy, you have to work toward that goal from the beginning.
Freethink: You've expressed some concern about the ethics of using CRISPR. Do you think there is a meaningful difference between enhancing human abilities — for example, using gene therapy to become stronger or more intelligent — versus correcting deficiencies, like Type 1 diabetes or Huntington's?
Dr. Jennifer Doudna: There is a meaningful distinction between enhancement and treatment, but that doesn't mean that the line is always clear. It isn't.
There's always a gray area when it comes to complex ethical issues like this, and our thinking on this is undoubtedly going to evolve over time.
What we need is to find an appropriate balance between preventing misuse and promoting beneficial innovation.
Freethink: What if it turns out that being physically stronger helps you live a longer life — if that's the case, are there some ways of improving health that we should simply rule out?
Dr. Jennifer Doudna: The concept of improving the "healthspan" of individuals is an area of considerable interest. Eliminating neurodegenerative disease will not only massively reduce suffering around the world, but it will also meaningfully increase the healthy years for millions of individuals.
"There is a meaningful distinction between enhancement and treatment, but that doesn't mean that the line is always clear. It isn't."
DR. JENNIFER DOUDNA
There will also be knock-on effects, such as increased economic output, but also increased impact on the planet.
When you think about increasing lifespans just so certain people can live longer, then not only do those knock-on effects become more central, you also have to ask who is benefiting and who isn't? Is it possible to develop this technology so the benefits are shared equitably? Is it environmentally sustainable to go down this road?
Freethink: Where do you see it going from here?
Dr. Jennifer Doudna: The bio revolution will allow us to create breakthroughs in treating not just a few but whole classes of previously unaddressed genetic diseases.
We're also likely to see genome editing play a role not just in climate adaptation, but in climate change solutions as well. There will be challenges along the way both expected and unexpected, but also great leaps in progress and benefits that will move society forward. It's an exciting time to be a scientist.
Freethink: If you had to guess, what is the first disease you think we are most likely to cure, in the real world, with CRISPR?
Dr. Jennifer Doudna: Because of the progress that has already been made, sickle cell disease and beta-thalassemia are likely to be the first diseases with a CRISPR cure, but we're closely following the developments of other CRISPR clinical trials for types of cancer, a form of congenital blindness, chronic infection, and some rare genetic disorders.
The pace of clinical trials is picking up, and the list will be longer next year.
A school lesson leads to more precise measurements of the extinct megalodon shark, one of the largest fish ever.
- A new method estimates the ancient megalodon shark was as long as 65 feet.
- The megalodon was one of the largest fish that ever lived.
- The new model uses the width of shark teeth to estimate its overall size.
A Florida student figured out a way to more accurately measure the size of one of the largest fish that ever lived – the extinct megalodon shark – and found that it was even larger than previously estimated.
The megalodon (officially named Otodus megalodon, which means "Big Tooth") lived between 3.6 and 23 million years ago and was thought to be about 34 feet long on average, reaching the maximum length of 60 feet. Now a new study puts that number at up to 65 feet (20 meters).
Homework assignment leads to a discovery
The study, published in Palaeontologia Electronica, used new equations extrapolated from the width of megalodon's teeth to make the improved estimates. The paper's lead author, Victor Perez, developed the revised methodology while he was a doctoral student at the Florida Museum of Natural History. He got the idea while teaching students, noticing a range of discrepancies in the results they were getting.
Students were supposed to calculate the size of megalodon based on the ancient fish's similarities to the modern great white shark. They utilized the commonly accepted method of linking the height of a shark's tooth to its total body length. As the press release from the Florida Museum of Natural History expounds, this method involves locating the anatomical position of a tooth in the shark's jaw, measuring the tooth "from the tip of the crown to the line where root and crown meet," and using that number in an appropriate equation.
But while carrying out calculations in this way, some of Perez's students thought the shark would have been just 40 feet long, while others were calculating 148 feet. Teeth located toward the back of the mouth were yielding the largest estimates.
"I was going around, checking, like, did you use the wrong equation? Did you forget to convert your units?" said Perez, currently the assistant curator of paleontology at the Calvert Marine Museum in Maryland. "But it very quickly became clear that it was not the students that had made the error. It was simply that the equations were not as accurate as we had predicted."
Found in North Carolina, these 46 fossils are the most complete set of megalodon teeth ever excavated.Credit: Jeff Gage/Florida Museum
The new approach
Perez's math exercise demonstrated that the equations in use since 2002 were generating different size estimates for the same shark based on which tooth was being measured. Because megalodon teeth are most often found as standalone fossils, Perez focused on a nearly complete set of teeth donated by a fossil collector to design a new approach.
Perez also had help from Teddy Badaut, an avocational paleontologist in France, who suggested using tooth width instead of height, which would be proportional to the length of its body. Another collaborator on the revised method was Ronny Maik Leder, then a postdoctoral researcher at the Florida Museum, who aided in the development of the new set of equations.
The research team analyzed the widths of fossil teeth that came from 11 individual sharks of five species, which included megalodon and modern great white sharks, and created a model that connects how wide a tooth was to the size of the jaw for each species.
"I was quite surprised that indeed no one had thought of this before," shared Leder, who is now director of the Natural History Museum in Leipzig, Germany. "The simple beauty of this method must have been too obvious to be seen. Our model was much more stable than previous approaches. This collaboration was a wonderful example of why working with amateur and hobby paleontologists is so important."
Why use teeth?
In general, almost nothing of the super-shark survived to this day, other than a few vertebrae and a large number of big teeth. The megalodon's skeleton was made of lightweight cartilage that decomposed after death. But teeth, with enamel that preserves very well, are "probably the most structurally stable thing in living organisms," Perez said. Considering that megalodons lost thousands of teeth during a lifetime, these are the best resources we have in trying to figure out information about these long-gone giants.
Researchers suggest megalodon's large jaws were very thick, made for grabbing prey and breaking its bones, exerting a bite force of up to 108,500 to 182,200 newtons.
Megalodon tooth compared to two great white shark teeth. Credit: Brocken Inaglory / Wikimedia.
Limitations of the new model
While the new model is better than previous methods, it's still far from perfect in precisely figuring out the sizes of animals which lived so long ago and left behind few if any full remains. Because individual sharks come in a variety of sizes, Perez warned that even their new estimates have an error range of about 10 feet when it comes to the largest animals.
Other ambiguities may affect the results, such as the width of the megalodon's jaw and the size of the gaps between its teeth, neither of which are accurately known. "There's still more that could be done, but that would probably require finding a complete skeleton at this point," Perez pointed out.
How did the megalodon go extinct?
Environmental changes that led to fluctuations in sea levels and disturbed ecosystems in the oceans likely led to the demise of these enormous ancient sharks. They were just too big to be sustained by diminishing food resources, says the ReefQuest Centre for Shark Research.
A 2018 study suggested that a supernova 2.6 million years ago hit Earth's atmosphere with so much cosmic energy that it resulted in climate change. The cosmic rays that included particles called muons might have caused a mass extinction of giant ocean animals ("the megafauna") that included the megalodon by causing mutations and cancer.
Scientists, led by Adrian Melott, professor emeritus of physics and astronomy at the University of Kansas, estimated that "the cancer rate would go up about 50 percent for something the size of a human — and the bigger you are, the worse it is. For an elephant or a whale, the radiation dose goes way up," as he explained in a press release.
We explore the history of blood types and how they are classified to find out what makes the Rh-null type important to science and dangerous for those who live with it.
- Fewer than 50 people worldwide have 'golden blood' — or Rh-null.
- Blood is considered Rh-null if it lacks all of the 61 possible antigens in the Rh system.
- It's also very dangerous to live with this blood type, as so few people have it.
Golden blood sounds like the latest in medical quackery. As in, get a golden blood transfusion to balance your tantric midichlorians and receive a free charcoal ice cream cleanse. Don't let the New-Agey moniker throw you. Golden blood is actually the nickname for Rh-null, the world's rarest blood type.
As Mosaic reports, the type is so rare that only about 43 people have been reported to have it worldwide, and until 1961, when it was first identified in an Aboriginal Australian woman, doctors assumed embryos with Rh-null blood would simply die in utero.
But what makes Rh-null so rare, and why is it so dangerous to live with? To answer that, we'll first have to explore why hematologists classify blood types the way they do.
A (brief) bloody history
Our ancestors understood little about blood. Even the most basic of blood knowledge — blood inside the body is good, blood outside is not ideal, too much blood outside is cause for concern — escaped humanity's grasp for an embarrassing number of centuries.
Absence this knowledge, our ancestors devised less-than-scientific theories as to what blood was, theories that varied wildly across time and culture. To pick just one, the physicians of Shakespeare's day believed blood to be one of four bodily fluids or "humors" (the others being black bile, yellow bile, and phlegm).
Handed down from ancient Greek physicians, humorism stated that these bodily fluids determined someone's personality. Blood was considered hot and moist, resulting in a sanguine temperament. The more blood people had in their systems, the more passionate, charismatic, and impulsive they would be. Teenagers were considered to have a natural abundance of blood, and men had more than women.
Humorism lead to all sorts of poor medical advice. Most famously, Galen of Pergamum used it as the basis for his prescription of bloodletting. Sporting a "when in doubt, let it out" mentality, Galen declared blood the dominant humor, and bloodletting an excellent way to balance the body. Blood's relation to heat also made it a go-to for fever reduction.
While bloodletting remained common until well into the 19th century, William Harvey's discovery of the circulation of blood in 1628 would put medicine on its path to modern hematology.
Soon after Harvey's discovery, the earliest blood transfusions were attempted, but it wasn't until 1665 that first successful transfusion was performed by British physician Richard Lower. Lower's operation was between dogs, and his success prompted physicians like Jean-Baptiste Denis to try to transfuse blood from animals to humans, a process called xenotransfusion. The death of human patients ultimately led to the practice being outlawed.4
The first successful human-to-human transfusion wouldn't be performed until 1818, when British obstetrician James Blundell managed it to treat postpartum hemorrhage. But even with a proven technique in place, in the following decades many blood-transfusion patients continued to die mysteriously.
Enter Austrian physician Karl Landsteiner. In 1901 he began his work to classify blood groups. Exploring the work of Leonard Landois — the physiologist who showed that when the red blood cells of one animal are introduced to a different animal's, they clump together — Landsteiner thought a similar reaction may occur in intra-human transfusions, which would explain why transfusion success was so spotty. In 1909, he classified the A, B, AB, and O blood groups, and for his work he received the 1930 Nobel Prize for Physiology or Medicine.
What causes blood types?
It took us a while to grasp the intricacies of blood, but today, we know that this life-sustaining substance consists of:
- Red blood cells — cells that carry oxygen and remove carbon dioxide throughout the body;
- White blood cells — immune cells that protect the body against infection and foreign agents;
- Platelets — cells that help blood clot; and
- Plasma — a liquid that carries salts and enzymes.6,7
Each component has a part to play in blood's function, but the red blood cells are responsible for our differing blood types. These cells have proteins* covering their surface called antigens, and the presence or absence of particular antigens determines blood type — type A blood has only A antigens, type B only B, type AB both, and type O neither. Red blood cells sport another antigen called the RhD protein. When it is present, a blood type is said to be positive; when it is absent, it is said to be negative. The typical combinations of A, B, and RhD antigens give us the eight common blood types (A+, A-, B+, B-, AB+, AB-, O+, and O-).
Blood antigen proteins play a variety of cellular roles, but recognizing foreign cells in the blood is the most important for this discussion.
Think of antigens as backstage passes to the bloodstream, while our immune system is the doorman. If the immune system recognizes an antigen, it lets the cell pass. If it does not recognize an antigen, it initiates the body's defense systems and destroys the invader. So, a very aggressive doorman.
While our immune systems are thorough, they are not too bright. If a person with type A blood receives a transfusion of type B blood, the immune system won't recognize the new substance as a life-saving necessity. Instead, it will consider the red blood cells invaders and attack. This is why so many people either grew ill or died during transfusions before Landsteiner's brilliant discovery.
This is also why people with O negative blood are considered "universal donors." Since their red blood cells lack A, B, and RhD antigens, immune systems don't have a way to recognize these cells as foreign and so leaves them well enough alone.
How is Rh-null the rarest blood type?
Let's return to golden blood. In truth, the eight common blood types are an oversimplification of how blood types actually work. As Smithsonian.com points out, "[e]ach of these eight types can be subdivided into many distinct varieties," resulting in millions of different blood types, each classified on a multitude of antigens combinations.
Here is where things get tricky. The RhD protein previously mentioned only refers to one of 61 potential proteins in the Rh system. Blood is considered Rh-null if it lacks all of the 61 possible antigens in the Rh system. This not only makes it rare, but this also means it can be accepted by anyone with a rare blood type within the Rh system.
This is why it is considered "golden blood." It is worth its weight in gold.
As Mosaic reports, golden blood is incredibly important to medicine, but also very dangerous to live with. If a Rh-null carrier needs a blood transfusion, they can find it difficult to locate a donor, and blood is notoriously difficult to transport internationally. Rh-null carriers are encouraged to donate blood as insurance for themselves, but with so few donors spread out over the world and limits on how often they can donate, this can also put an altruistic burden on those select few who agree to donate for others.
Some bloody good questions about blood types
A nurse takes blood samples from a pregnant woman at the North Hospital (Hopital Nord) in Marseille, southern France.
Photo by BERTRAND LANGLOIS / AFP
There remain many mysteries regarding blood types. For example, we still don't know why humans evolved the A and B antigens. Some theories point to these antigens as a byproduct of the diseases various populations contacted throughout history. But we can't say for sure.
In this absence of knowledge, various myths and questions have grown around the concept of blood types in the popular consciousness. Here are some of the most common and their answers.
Do blood types affect personality?
Japan's blood type personality theory is a contemporary resurrection of humorism. The idea states that your blood type directly affects your personality, so type A blood carriers are kind and fastidious, while type B carriers are optimistic and do their own thing. However, a 2003 study sampling 180 men and 180 women found no relationship between blood type and personality.
The theory makes for a fun question on a Cosmopolitan quiz, but that's as accurate as it gets.
Should you alter your diet based on your blood type?
Remember Galen of Pergamon? In addition to bloodletting, he also prescribed his patients to eat certain foods depending on which humors needed to be balanced. Wine, for example, was considered a hot and dry drink, so it would be prescribed to treat a cold. In other words, belief that your diet should complement your blood type is yet another holdover of humorism theory.
Created by Peter J. D'Adamo, the Blood Type Diet argues that one's diet should match one's blood type. Type A carriers should eat a meat-free diet of whole grains, legumes, fruits, and vegetables; type B carriers should eat green vegetables, certain meats, and low-fat dairy; and so on.
However, a study from the University of Toronto analyzed the data from 1,455 participants and found no evidence to support the theory. While people can lose weight and become healthier on the diet, it probably has more to do with eating all those leafy greens than blood type.
Are there links between blood types and certain diseases?
There is evidence to suggest that different blood types may increase the risk of certain diseases. One analysis suggested that type O blood decreases the risk of having a stroke or heart attack, while AB blood appears to increase it. With that said, type O carriers have a greater chance of developing peptic ulcers and skin cancer.
None of this is to say that your blood type will foredoom your medical future. Many factors, such as diet and exercise, hold influence over your health and likely to a greater extent than blood type.
What is the most common blood type?
In the United States, the most common blood type is O+. Roughly one in three people sports this type of blood. Of the eight well-known blood types, the least common is AB-. Only one in 167 people in the U.S. have it.
Do animals have blood types?
They most certainly do, but they are not the same as ours. This difference is why those 17th-century patients who thought, "Animal blood, now that's the ticket!" ultimately had their tickets punched. In fact, blood types are distinct between species. Unhelpfully, scientists sometimes use the same nomenclature to describe these different types. Cats, for example, have A and B antigens, but these are not the same A and B antigens found in humans.
Interestingly, xenotransfusion is making a comeback. Scientists are working to genetically engineer the blood of pigs to potentially produce human compatible blood.
Scientists are also looking into creating synthetic blood. If they succeed, they may be able to ease the current blood shortage, while also devising a way to create blood for rare blood type carriers. While this may make golden blood less golden, it would certainly make it easier to live with.* While antigens are typically proteins, they can be other molecules as well, such as polysaccharides.
Milgram's experiment is rightly famous, but does it show what we think it does?
- In the 1960s, Stanley Milgram was sure that good, law-abiding Americans would never be able to follow orders like the Germans in the Holocaust.
- His experiments proved him spectacularly wrong. They showed just how many of us are willing to do evil if only we're told to by an authority figure.
- Yet, parts of the experiment were set up in such a way that we should perhaps conclude something a bit more nuanced.
Holding a clipboard and wearing a lab coat makes you a very powerful person. Add in a lanyard and a confident voice, and you're pretty much in Ocean's Eleven.
Though we believe ourselves to be contrarians, most of us like to obey authority. We answer questions, help with any number of tasks, and obey commands unthinkingly. The vast majority of the time, this is relatively harmless and even requisite for a functioning society, but it can also lead humanity to very dark places.
It could happen here
As we've seen with Asch's experiments on conformity, the post-World War II community was determined to answer how and why the Holocaust took place. Just after the trial of Adolf Eichmann, the American media and public came to see German society as some special kind of monster in just how willing they were to follow orders unthinkingly, at odds with any sense of duty or morality.
Into this came Stanley Milgram. In 1961, Milgram set out a series of experiments to show, in his view, how the German people were more susceptible to authoritarianism than Americans. Milgram believed, as a lot of people did, that the American people would never be capable of such horrendous evil.
The experiment was to be set up in two stages: the first would be on American subjects, to gauge how far they would obey orders; the second would be on Germans, to prove how much they differed. The results stopped Milgram in his tracks.
Shock, shock, horror
Milgram wanted to ensure that his experiment involved as broad and diverse a group of people as possible. In addition to testing the American vs. German mindset, he wanted to see how much age, education, employment, and so on affected a person's willingness to obey orders.
So, the original 40 participants he gathered came from a wide spectrum of society, and each was told that they were to take part in a "memory test." They were to determine the extent to which punishment affects learning and the ability to memorize.
Milgram believed, as a lot of people did, that the American people would never be capable of such horrendous evil.
The experiment involved three people. First, there was the "experimenter," dressed in a lab coat, who gave instructions and prompts. Second, there was an actor who was the "learner." Third, there was the participant who thought that they were acting as the "teacher" in the memory test. The apparent experimental setup was that the learner had to match two words together after being taught them, and whenever they got the answer wrong, the teacher had to administer an electric shock. (The teachers (participants) were shocked as well to let them know what kind of pain the learner would experience.) At first, the shock was set at 15 volts.
The learner (actor) repeatedly made mistakes for each study, and the teacher was told to increase the voltage each time. A tape recorder was played that had the learner (apparently) make sounds as if in pain. As it went on, the learner would plead and beg for the shocks to stop. The teacher was told to increase the amount of voltage as punishment up to a level that was explicitly described as being fatal — not least because the learner was desperately saying he had a heart condition.
The question Milgram wanted to know: how far would his participants go?
Just obeying orders
The results were surprising. Sixty-five percent of the participants were willing to give a 450-volt shock described as lethal, and all administered a 300-volt shock described as traumatically painful. It should be repeated, this occurred despite the learner (actor) begging the teacher (participant) to stop.
In the studies that came after, in a variety of different setups, that 60 percent number came up again and again. They showed that roughly two out of three people would be willing to kill someone if told to by an authority figure. Milgram proved that all genders, ages, and nationalities were depressingly capable of inflicting incredible pain or worse on innocent people.
Major limitations in Milgram's experiment
Milgram took many steps to make sure that his experiment was rigorous and fair. He used the same tape recording of the "learner" screaming, begging, and pleading for all participants. He made sure the experimenters used only the same four prompts each time when the participants were reluctant or wanted to stop. He even made sure that he himself was not present at the experiment, lest he interfere with the procedure (something Phillip Zimbardo did not do).
But, does the Milgram experiment actually prove what we think it does?
First, the experimenters were permitted to remind the participants that they were not responsible for what they did and that the team would take full blame. This, of course, does not make the study any less shocking, but it does perhaps change the scope of the conclusions. Perhaps the experiment reveals more about our ability to surrender responsibility and our willingness simply to become a tool. The conclusion is still pretty depressing, but it shows what we are capable of when offered absolution rather than when simply following orders.
Second, the experiment took place in a single hour, with very little time either to deliberate or talk things over with someone. In most situations, like the Holocaust, the perpetrators had ample time (years) to reflect on their actions, and yet, they still chose to turn up every day. Milgram perhaps highlights only how far we'll go in the heat of the moment.
Finally, the findings do not tell the whole tale. The participants were not engaging in sadistic glee to shock the learner. They all showed signs of serious distress and anxiety, such as nervous laughing fits. Some even had seizures. These were not willing accomplices but participants essentially forced to act a certain way. (Since then, many scientists have argued that Milgram's experiment is hugely unethical.)
The power of authority
That all being said, there's a reason why Milgram's experiment stays with us today. Whether it's evolutionarily or socially drilled into us, it seems that humans are capable of doing terrible things, if only we are told to do so by someone in power — or, at the very least, when we don't feel responsible for the consequences.
One silver lining to Milgram is in how it can inoculate us against such drone-like behavior. It can help us to resist. Simply knowing how far we can be manipulated helps allow us to say, "No."