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10 new things we’ve learned about cancer
Cancer's sweet tooth. Turning cancer cells into fat. Unveiling genetic secrets. Scientists are learning about cancer every day.
- Cancer is a leading cause of death among Americans, second only to heart disease.
- Researchers are unearthing cancer's genetic secrets and, with it, potential new treatments.
- Their efforts have seen the cancer death rate for men, women, and children fall year after year between 1999 and 2016.
The 21st century has been, and will continue to be, shaped by cancer. Although heart disease remains the United States' number one killer, cancer is quickly closing the gap and may soon surpass it. Some oncologists claim a cure is five, 10, certainly no more than 20 years away. Others aren't so sure because, in a way, cancer is the price we pay for evolutionary success.
"It is no coincidence that the very genes that allow our embryos to grow — our hands to grow, our feet to grow — if you mutate them in inappropriate contexts, [they] will ultimately release the disease that kills us," said oncologist Siddhartha Mukherjee, who dubbed cancer the Emperor of All Maladies, also the title of his Pulitzer Prize-winning book.
Whether for five years or forever, cancer won't be going anywhere any time soon. Yet, the more doctors and scientists discover about it, the better we can learn to live with it.
A love-hate relationship: Cancer and antioxidants
Contrary to what many believe, cancer enjoys a nutrient-rich diet as much as the next cell because it helps it grow, even those legendary antioxidants.
In two independent studies published in Cell, Swedish and American research teams found that lung cancer utilizes antioxidants to activate a protein called BACH1. This protein stimulates the cancer cells to metabolize glucose and accelerate metastasis. Even without a ready supply of dietary antioxidants available, the tumor would simply produce its own.
Professor Martin Bergo, who led the Swedish study, hopes this research will help develop new treatments. "We now have important new information on lung cancer metastasis, making it possible for us to develop new treatments, such as ones based on inhibiting BACH1," he said in a release.
Does this mean you should abstain from antioxidant-rich foods? Not at all. Antioxidants do neutralize the free radicals that cause oxidative stress on cells. Preventing such cell damage can help prevent cancer.
However, it's best to avoid antioxidant supplements unless prescribed by a doctor. As reported by the National Cancer Institute, of nine randomized-controlled clinical trials, none provided evidence that such supplements lower cancer risks. A few even found that beta-carotene supplements increased the risk of lung cancer so severely that the trials had to be ended prematurely.
Get your antioxidants from fruits, veggies, and beans instead. Research suggests that these antioxidants work in combination with additional molecules found in the whole foods. It's this tag-team effect that ultimately give antioxidants their salubrious power.
Cancer costs (in more ways than one)
It goes without saying that cancer is costly. The physical strain of treatment. The potential loss of life, whether one's own or the life of a loved one. And even if one survives, there's the emotional cost of the ordeal.
But the toll imposed by cancer is more than physical or psychological. A study released last year found "that 42 percent of patients deplete their life savings during the first two years of treatment." Of the 9.5 million newly diagnosed cancer patients surveyed, the study calculated average losses at $92,098.
Its authors dubbed the effect "financial toxicity" and concluded: "As large financial burdens have been found to adversely affect access to care and outcomes, the active development of approaches to mitigate these effects among already vulnerable groups remains of key importance."
Cancer's sweet tooth
A recent study found a positive association between a daily sugary drink and an increased risk of cancer.
Researchers asked more than 100,000 people to complete surveys looking at their usual consumption of 3,300 foods and beverages. The results? A positive association between daily consumption of a sugary beverage and an increased risk of cancer. The sugary drinks not only included soda but also 100 percent fruit juice and artificially sweetened drinks.
"These data support the relevance of existing nutritional recommendations to limit sugary drink consumption, including 100% fruit juice, as well as policy actions, such as taxation and marketing restrictions targeting sugary drinks, which might potentially contribute to the reduction of cancer incidence," the researchers stated in a release.
Don't go trashing the OJ just yet, though. As an observational study, the data could not establish a cause-effect relationship, and the researchers note the results are only preliminary. Additionally, the results hinge on the memories of the participants. (What exactly did you eat for breakfast the Monday before last?)
But the study helps stress the American Institute for Cancer Research's (AICR) suggestion to limit sugary beverages. Try to remove soda from your diet. Drink 100 percent fruit juices with no added sugar sparingly. And of course, enjoy an active, healthy lifestyle.
Cancer on the grill
It's a summer tradition to throw some meat on the grill alongside a good beer. But grilled meats hide a few furtive carcinogens: polycyclic aromatic hydrocarbons and heterocyclic aromatic amines.
The hydrocarbons are carried in the smoke after fat burns on the flame, while the heterocyclic amines form when sugars, amino acids, and creatine react at high heats. Neither has been proven to cause cancer, but they are known mutagens that can damage DNA after being metabolized.
"Research shows that diets high in red and processed meat increase risk for colon cancer," said Alice Bender, AIRC Senior Director of Nutrition Programs. "And grilling meat, red or white, at high temperatures forms potent cancer-causing substances."
Like sugary drinks, however, you don't have to forever hang up your "Kiss the Cook" apron. The institute has several suggestions for safe summer grilling, such as limiting red meat, marinating foods beforehand, keeping a low flame, and throwing more vegetables into the mix.
A unified theory of leukemia
Acute lymphoblastic leukemia (ALL) afflicts about one in 2,000 children, and Mel Greaves, at the Institute of Cancer Research, London, believes he's found the cause. Researching 30 years of data and medical literature on childhood leukemia, he argues the "delayed infection" is the culprit.
According to this theory, children develop a pre-leukemia mutation in utero. The mutation remains inert until later in life when the child encounters a common infection. The microbes then trigger secondary genetic changes that led to overt leukemia.
Does this mean children are safe only in cleanrooms? Strike that, reverse it. Greaves believes exposure to germs in the first year of life is proactive. It trains the immune system to deal with pathogens, therefore preventing the secondary mutation from triggering.
"Childhood ALL can be viewed as a paradoxical consequence of progress in modern societies, where behavioral changes have restrained early microbial exposure," Greaves writes. "This engenders an evolutionary mismatch between historical adaptations of the immune system and contemporary lifestyles. Childhood ALL may be a preventable cancer."
The future of cancer treatment is genetic
A major stride toward our understanding of cancer came with the Human Genome Project. Why? At its core, cancer is a genetic disease.
Our ability to sequence and read cancerous genomes will be a major step toward cancer treatments. As Eric Green, director of the National Human Genome Research Institute, told Big Think:
"[The] standard of care for many types of cancer is going to be: Get that tumor, read out its DNA, sequence its genome and based on what you've seen what's wrong with that tumor -- not by looking at it under a microscope only or by looking at it in a sort of a gross fashion but actually looking inside its blueprint -- you will be able to have a much better way of deciding what types of treatments to pursue and have a much better idea about what's wrong in that kind of tumor."
A future treatment? The "cancer vaccine"
An airman receives a vaccine. Could the future of cancer treatment be as easy as a shot?
Rather than using chemotherapy to combat cancer with the subtlety of an atomic bomb, immunotherapies aim to uncloak cancer cells, so the body's immune system can go on the offensive
One example of an immunotherapeutic approach is the so-called "cancer vaccine." During its clinical trial, 11 patients had a tumor injected with a steroid to bolster the site's dendritic cells — immune system cells that specialize in processing antigens.
Following a light dose of radiation and a stimulant, the patients' dendritic cells directed T-cells to attack the cancer cells. Once the T-cells could recognize the tumor, they became able to locate cancer cells throughout the body.
Of the 11 patients, three saw their cancer go into regression or remission. Six others had their cancer stymied for at least three months.
"It's really promising, and the fact you get not only responses in treated areas, but areas outside the field [of treatment with radiation] is really significant," Dr. Silvia Formenti, chairwoman of radiation oncology at Weill Cornell Medicine and New York Presbyterian, told CNBC. (Dr. Formenti was not involved in the study.)
Turning tumors into fat
Cancer cells spreading to other parts of the body through the circulatory system.
A deadly tool in cancer's arsenal is cell plasticity, a cell's ability to alter its physiological characteristics. It is one of the reasons cancers can metastasize throughout the body, and it helps the disease resist treatments.
Researchers at the University of Basel, Switzerland, have hijacked this ability and turned it against cancer. Using a drug therapy that combined an anti-diabetic drug and MEK inhibitors, they attacked cancer cells and turned them into adipocytes (a.k.a. fat cells).
While this did not remove the tumor, it did make the cells post-miotic, meaning they could no longer divide. This inhibited the cancer's ability to spread.
"In future, this innovative therapeutic approach could be used in combination with conventional chemotherapy to suppress both primary tumor growth and the formation of deadly metastases," senior study author Gerhard Christofori told Medical News Today.
An image of the E. coli bacteria. Will these become the next breakthrough in cancer therapies?
Another advancement in cancer treatment is synthetic biology, a field in which scientists use the principals of engineering to redesign biological systems. In one example, researchers genetically programmed a non-pathogenic E. coli strain to attack tumors in lab mice.
Once injected, the rewired bacteria took refuge in the tumor, where they self-destructed. These dead bacteria leaked from the tumor, and thanks to encoded nanobodies, drew the attention of T-cells which devoured the bacteria and tumor alike.
Of course, lab tests in mice do not guarantee a successful transition to human patients, but it remains a promising avenue for treatment.
"At some point in the future, we will use programmable bacteria for treatment," Michael Dougan, an immunologist at Massachusetts General Hospital, told the New York Times. "I think there's just too much potential."
A new attitude toward cancer
Medical professionals originally viewed cancer as a disease to be destroyed with extreme prejudice; the treatment was only better than the disease because the disease ended in death.
But as David Agus, professor of medicine and engineering at USC, told us, there are better ways to approach cancer:
"Well, to me cancer is a verb and not a noun. You're cancering, it's something the body does and not that the body gets. And so that philosophy needs a very different way of approaching disease, and it means changing the system in addition to trying to target the cancer."
One way is to approach treatment holistically. Agus points to a trial that gave premenopausal women with breast cancer a bone-building drug. The drug didn't target the cancer, yet it reduced recurrence by 40 percent because breast cancer metastasizes in bone.
Another method is psychosocial oncology. In this relatively new field, the practitioners' goal is to enhance the quality of life for cancer patients through mental health care as a part of physical care.
Living with cancer
Cancer death rates in the United States by cancer type, male and female, age standardized.
Scientists have learned a lot about cancer, but there remains much we don't know. Does that mean we should despair for the future? Quite the contrary. Thanks to the knowledge accumulated by scientists, we have much to be hopeful for.
Headlines are correct that the total number of new cancer cases and deaths continue to increase. However, the rates of cancer diagnoses and death have declined year after year. This is because absolute numbers don't account for metrics like population growth and increased life expectancy. In fact, the Annual Report to the Nation on the Status of Cancer found that the cancer death rate for men, women, and children fell year after year between 1999 and 2016, as did cancer incident rates.
"Death in old age is inevitable. The job of science is to prevent unanticipated deaths in unanticipated times. I find that is a perfectly reasonable goal," said Mukerjee. "If you're saying to me that we will have a more profound, more proximal reconciliation with cancer in the next few decades, I think the answer is absolutely yes."
We may not be able to eradicate cancer as we did with diseases like smallpox and polio. But we're learning how to live with it more and more every day.
- Organic food reduces cancer risk by 25% - Big Think ›
- Great white shark genome reveals clues about cancer - Big Think ›
- New therapy turns cancer into fat to stop its spread - Big Think ›
Inventions with revolutionary potential made by a mysterious aerospace engineer for the U.S. Navy come to light.
- U.S. Navy holds patents for enigmatic inventions by aerospace engineer Dr. Salvatore Pais.
- Pais came up with technology that can "engineer" reality, devising an ultrafast craft, a fusion reactor, and more.
- While mostly theoretical at this point, the inventions could transform energy, space, and military sectors.
The U.S. Navy controls patents for some futuristic and outlandish technologies, some of which, dubbed "the UFO patents," came to light recently. Of particular note are inventions by the somewhat mysterious Dr. Salvatore Cezar Pais, whose tech claims to be able to "engineer reality." His slate of highly-ambitious, borderline sci-fi designs meant for use by the U.S. government range from gravitational wave generators and compact fusion reactors to next-gen hybrid aerospace-underwater crafts with revolutionary propulsion systems, and beyond.
Of course, the existence of patents does not mean these technologies have actually been created, but there is evidence that some demonstrations of operability have been successfully carried out. As investigated and reported by The War Zone, a possible reason why some of the patents may have been taken on by the Navy is that the Chinese military may also be developing similar advanced gadgets.
Among Dr. Pais's patents are designs, approved in 2018, for an aerospace-underwater craft of incredible speed and maneuverability. This cone-shaped vehicle can potentially fly just as well anywhere it may be, whether air, water or space, without leaving any heat signatures. It can achieve this by creating a quantum vacuum around itself with a very dense polarized energy field. This vacuum would allow it to repel any molecule the craft comes in contact with, no matter the medium. Manipulating "quantum field fluctuations in the local vacuum energy state," would help reduce the craft's inertia. The polarized vacuum would dramatically decrease any elemental resistance and lead to "extreme speeds," claims the paper.
Not only that, if the vacuum-creating technology can be engineered, we'd also be able to "engineer the fabric of our reality at the most fundamental level," states the patent. This would lead to major advancements in aerospace propulsion and generating power. Not to mention other reality-changing outcomes that come to mind.
Among Pais's other patents are inventions that stem from similar thinking, outlining pieces of technology necessary to make his creations come to fruition. His paper presented in 2019, titled "Room Temperature Superconducting System for Use on a Hybrid Aerospace Undersea Craft," proposes a system that can achieve superconductivity at room temperatures. This would become "a highly disruptive technology, capable of a total paradigm change in Science and Technology," conveys Pais.
High frequency gravitational wave generator.
Credit: Dr. Salvatore Pais
Another invention devised by Pais is an electromagnetic field generator that could generate "an impenetrable defensive shield to sea and land as well as space-based military and civilian assets." This shield could protect from threats like anti-ship ballistic missiles, cruise missiles that evade radar, coronal mass ejections, military satellites, and even asteroids.
Dr. Pais's ideas center around the phenomenon he dubbed "The Pais Effect". He referred to it in his writings as the "controlled motion of electrically charged matter (from solid to plasma) via accelerated spin and/or accelerated vibration under rapid (yet smooth) acceleration-deceleration-acceleration transients." In less jargon-heavy terms, Pais claims to have figured out how to spin electromagnetic fields in order to contain a fusion reaction – an accomplishment that would lead to a tremendous change in power consumption and an abundance of energy.
According to his bio in a recently published paper on a new Plasma Compression Fusion Device, which could transform energy production, Dr. Pais is a mechanical and aerospace engineer working at the Naval Air Warfare Center Aircraft Division (NAWCAD), which is headquartered in Patuxent River, Maryland. Holding a Ph.D. from Case Western Reserve University in Cleveland, Ohio, Pais was a NASA Research Fellow and worked with Northrop Grumman Aerospace Systems. His current Department of Defense work involves his "advanced knowledge of theory, analysis, and modern experimental and computational methods in aerodynamics, along with an understanding of air-vehicle and missile design, especially in the domain of hypersonic power plant and vehicle design." He also has expert knowledge of electrooptics, emerging quantum technologies (laser power generation in particular), high-energy electromagnetic field generation, and the "breakthrough field of room temperature superconductivity, as related to advanced field propulsion."
Suffice it to say, with such a list of research credentials that would make Nikola Tesla proud, Dr. Pais seems well-positioned to carry out groundbreaking work.
A craft using an inertial mass reduction device.
Credit: Salvatore Pais
The patents won't necessarily lead to these technologies ever seeing the light of day. The research has its share of detractors and nonbelievers among other scientists, who think the amount of energy required for the fields described by Pais and his ideas on electromagnetic propulsions are well beyond the scope of current tech and are nearly impossible. Yet investigators at The War Zone found comments from Navy officials that indicate the inventions are being looked at seriously enough, and some tests are taking place.
If you'd like to read through Pais's patents yourself, check them out here.
Laser Augmented Turbojet Propulsion System
Credit: Dr. Salvatore Pais
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.