RealClearScience Newton Blog

Can Fish Survive in Milk?

Ross Pomeroy - June 19, 2019

Fish live in water, and skim milk is roughly 90.4% water, so could fish live, or at least respire, in milk?

A curious Redditor recently posed this simple, yet thought-provoking question to the AskScience subreddit. The simple answer is "no," but the nuanced response sheds light on how fish, and all other organisms, function.

Fish have evolved over many millions of years to survive in water with a certain amount of dissolved oxygen, acidity, and other trace molecules. So, though skim milk is nine-tenths water, it still would be entirely insufficient to support a fish for long. The differences in acidity and dissolved oxygen, not to mention all of the fat, proteins, carbohydrates, and other minerals in the milk that might clog the creature's gills, would quickly spell trouble. The animal would likely die within minutes, if not sooner.

If you think about it, skim milk is essentially just heavily polluted water. And even relatively mild pollution can bring about massive fish kills.

Why Is There Magnetite in the Human Brain?

Ross Pomeroy - June 11, 2019

Like the Marvel comic book hero, we are all iron men and women. Iron composes the heme of hemoglobin, the red pigment in our blood. It's stored in ferritin, a protein ubiquitous in almost all living organisms. And, most curiously, it's found in mineral form within the human brain.

That iron mineral is magnetite (Fe3O4), and its name is an obvious clue to its most intriguing property: magnetite is the most magnetic of Earth's naturally-occurring minerals.

So what is a magnetic mineral doing inside our brains? Caltech geobiologist Joseph Kirschvink thinks he might have the answer: Magnetite allows us to sense Earth's magnetic field.

This remarkable ability is present all across the animal kingdom, from bacteria and birds to turtles and bats. Sensing the planet's geomagnetism grants these creatures a keen sense of direction and location, known as magnetoreception. Being able to orient on Earth is obviously a huge advantage, so it's no wonder that this ability is so widespread.

Submarines and Landsailers: Five Futuristic Concepts for NASA Missions

Ross Pomeroy - June 4, 2019

Much of the science performed at NASA borders on fiction. Their job is to bring it into reality. One team intimately familiar with this task at the space agency is called COMPASS. Since 2006, their job has been to take the most preliminary ideas for space exploration and mold them into real, executable plans. A few of those plans have come to fruition, some are currently being worked on, and many more have been abandoned. All, however, are bold visions of future NASA missions – simultaneously fascinating and inspiring.

Here are five of COMPASS' coolest designs:

1. Mars Ascent Vehicle. You may have heard of the Mars Ascent Vehicle, or MAV, from Andy Weir's book The Martian, but the idea was originally born from a COMPASS design in 2010.  The basic plan is for a launch platform upon which rests a lightweight rocket. This rocket transports Mars samples from the planet's surface into orbit, where they can be picked up by a waiting ship and returned to Earth. Subsequent considerations involve making a MAV that can be used to ferry astronauts from the planet's surface. Some form of the MAV will undoubtedly be used should humans ever make it to the Red Planet.


Lessons From the Great Antioxidant Lie

Ross Pomeroy - May 28, 2019

Antioxidants have been hailed as health game changers for over a quarter-century. When originally buzzed back in the early 1990s, the compounds, which include beta-carotene, Vitamin E, and glutathione, were predicted to protect against various cancers, heart disease, and neurodegradation. They'd do this by halting the spread of free radicals in the body, molecules with unpaired electrons that greedily rob other molecules of their electrons in order to stabilize. By stealing electrons to pair their own, however, they create more free radicals in the process, producing "oxidative stress." Antioxidants graciously lend their electrons to free radicals without turning ravenous themselves, thus halting the damaging chain reaction.

Early on, in vitro and observational studies showed promise, exciting scientists. Health "gurus" hyped the findings with books and articles. Supplement sellers had a new fad to fill their coffers. Food makers began slapping antioxidant claims on everything from yogurt and snack bars to chocolate and soda. The antioxidant craze was on.

But then, in the early 2000s, results from randomized, controlled trials on humans began flowing in, and the stream of positive results soon turned into a torrent of negative findings. Perhaps the trials weren't long enough, or were conducted on the wrong study populations, some scientists wondered. Over the next decade, more experiments concluded, with more inconclusive or outright negative results. Antioxidant intake didn't boost cognitive performance, or stall dementia, or halt heart disease, or prevent cancer, or lower the risk of Parkinson's.

Today, it's increasingly accepted in the scientific community that antioxidants are not the health promoters they were hoped to be.

How Statistics Rewards Us for Being Mean to Each Other

Ross Pomeroy - May 21, 2019

It's an unfortunate staple of human nature: all too often, we're mean to others when they screw up or perform poorly. Flunk a test? Then a parent might ground you. Lose a match? Then your coach might yell at you. Botch a presentation? Then your boss might demote you. Even more unfortunate, statistics reinforces these acts of nastiness, even though psychological research suggests they don't actually help.

Nobel Prize-winning psychologist Daniel Kahneman explained this twisted phenomenon in his bestselling book Thinking, Fast and Slow. Earlier in his career, he was teaching flight instructors in the Israeli Air Force that rewarding good performance works better than punishing mistakes, as evinced by scientific research. One of his "students" ardently disagreed, however, citing his own experience that after praising cadets for a well-executed flight maneuver, they usually perform worse on the next try. On the other hand, a harsh rebuke after a failed attempt almost always leads to a better subsequent outcome.

Kahneman wasn't deterred by the flight instructor's anecdote. Instead, he was enthused.

"The instructor was right–but he was also completely wrong!" he recollected. "The inference he had drawn about the efficacy of reward and punishment was completely off the mark."

Are Homophobic Men Turned On by Gay Porn?

Ross Pomeroy - May 9, 2019

In 1996, psychologists at the University of Georgia reported an intriguing, controversial result: Heterosexual young men with homophobic beliefs were aroused by gay porn, while their nonhomophobic straight peers were not.

Since the study was published, it has been touted in some circles as proof that many homophobic men are in fact secretly gay themselves.

"The point is that these men already have this arousal naturally, but that they block it because they do not see it as socially acceptable," Dr. Nathan Heflick, a Senior Lecturer in the School of Psychology at the University of Lincoln, wrote on the study. "So they form extra strong anti-gay attitudes as a means of appearing heterosexual to others, and perhaps trying to convince themselves they are entirely heterosexual."

But as we are now realizing with so many other seductive findings – and the psychological studies that produce them – this one may not be as firmly grounded as originally assumed. Just 64 heterosexual men, all college students, comprised the original study group. Moreover, the method used to assess sexual arousal, the penile plethysmograph, a device that measures blood flow to the penis, has recently come under fire in judicial and academic circles for variation in testing and the potential for false results. Moreover, the University of Georgia researchers admitted the possibility that "viewing homosexual stimuli causes negative emotions such as anxiety in homophobic men but not in nonhomophobic men. Because anxiety has been shown to enhance arousal and erection, this theory would predict increases in erection in homophobic men."

What Do Swordfish Use Their "Swords" For?

Ross Pomeroy - April 30, 2019

It's easy to envision: A sleek swordfish, many meters long and massive, flaps its powerful tailfin, rapidly accelerating through the ocean water at breakneck speed, until it spears its helpless prey. Wait a second... Then what? How does the swordfish get the fish off its "sword" and into its mouth? It doesn't make any sense!

That's because none of this actually happens.

Turns out, the "swords," or bills, of billfish like marlin, sailfish, and swordfish, are indeed used for hunting, but not as devices to impale prey. Rather, they are wielded as scythes to swipe at larger prey or through schools of smaller fish, knocking them senseless so they can be easily gobbled up.

A few years ago, a team of researchers filmed sailfish underwater swinging their bills at sardines at dizzying accelerations, some of "the highest... ever recorded in an aquatic vertebrate," they remarked. What's more, the merciless attacks were relatively covert – sailfish inserting their foot-long bills into fish schools often didn't elicit an evasive response from their targets.

The Five Most Anti-Science Documentaries on Netflix

Ross Pomeroy - April 23, 2019

Netflix brought in $15.8 billion in revenue in 2018 in part because the streaming service floods subscribers with a deluge of binge-worthy content. That's all fine and well when the show is Stranger Things or The Great British Baking Show, but when it's a media production that mangles science and spreads misinformation, it's a problem. Unfortunately, Netflix hosts a variety of documentaries that do just that. Here are the worst offenders:

1. Stink! Filmmaker and father John Whelan spends a lot of time on the phone trying to track down the "toxic" chemicals in his daughter's pajamas, all while asserting that we are guinea pigs of industry bathed in a sea of chemicals. Throughout, he completely ignores the basic principle of toxicology that "the dose makes the poison." This scaremongering documentary can't help but mention the words "toxic" and "chemicals" every other sentence, a tactic of repitition in lieu of scientific evidence to make its ultimate point: "We are quietly becoming genetically modified by toxic chemicals," and the only way to stop it is to get rid of "synthetic" chemicals in favor of "natural" ones.

2. The Magic Pill. Australian celebrity chef Pete Evans loves the ketogenic diet, which encourages eating high amounts of fat and protein and little to no carbohydrates. He loves it so much, in fact, that he made a feature documentary claiming that the diet can treat cancer, autism, and even asthma. Legitimate health experts weren't amused, and the Australian Medical Association even called for the film to be removed from Netflix. This isn't Evans' first run in with woo. In the past, the chef denied the efficacy of fluoride in combating cavities and claimed that sunscreen is toxic.

3. Cowspiracy. Did you know that animal agriculture is the leading contributor to climate change, responsible for more than half of all carbon emissions, more than fossil fuel energy as well as any other factor? No? Good. Because it's completely untrue. This is the lie at the heart of Cowspiracy, which claims that if the world's population "simply" went vegan, we'd save the planet. More nuanced, evidence-based evaluations find that eliminating meat from our collective diet actually wouldn't be as beneficial as claimed. Pesticide production would have to go way up to make up for all the lost fertilizer in the form of manure, and many more people would face nutritional deficiencies.

The Rare Disease That Turns People to Bone

Ross Pomeroy - April 16, 2019

In Greek mythology, Medusa was a winged woman with slithering snakes in place of strands of hair. All who gazed upon her monstrous face would turn to stone. A curious genetic disease strikes sufferers with a semblance of the horrible fate inflicted upon Medusa's victims.

Fibrodysplasia ossificans progressiva (FOP) gradually turns fibrous tissues like muscles, tendons, and ligaments into bone. The genetic disorder afflicts fewer than one in two million people. As of 2017, only 800 confirmed cases have been identified. All of these patients share a near identical story: At birth, they emerged from the womb with mysteriously malformed big toes – short, stubby, and without a skin crease on account of the toe having only a single phalanx rather than the usual two. As infants, their lives progressed without much incident until between the ages of three and four, when the hallmark ossification, or bone growth, typically begins. Whether spontaneously or in the wake of some sort of physical trauma, lumps form around the neck accompanied by reddishness of the skin and occasionally bruising. Then, over a matter of months, the nearby muscles, tendons, and ligaments slowly harden, transforming to bone. The metamorphosis continues over the ensuing years, first striking the shoulders, then moving to the arms and chest, and finally progressing down to the legs and feet. By age thirty, almost all those afflicted with FOP are locked within cages of their own skeletons, often unable to move at all. By age forty, most die from complications related to the disease.

While FOP was initially documented in the 17th century, most of our knowledge about the condition came on account of the experience of Harry Raymond Eastlack, Jr. Born in Philadelphia, Eastlack struggled with FOP since the age of four. Each year, he lost more and more mobility, eventually only having control over his eyes, tongue, and lips. Before dying of pneumonia at age 39, he expressed the fervent desire to donate his skeleton to science. It has now been displayed at the legendary Mütter Museum in the College of Physicians of Philadelphia for well over forty years, and is heavily utilized as a reference by researchers studying FOP.

In 2006, some of those researchers led by Frederick Kaplan at the University of Pennsylvania pinpointed the precise gene responsible for causing FOP. ACVR1 is integral to bodily repair, but when mutated, the repair mechanism goes haywire. This explains one of FOP's most disturbing effects: any sort of trauma, from a knock on the thigh to the stab of a needle, can cause the surrounding tissue to slowly ossify. Early sufferers of the disease found this out the hard way. In the mid 20th century, surgeons would attempt to remove excess bone growth only to find the practice futile. Painfully, relentlessly, the bone always grew back, often leaving patients even more disabled than before their surgeries.

Did 19th Century Corsets Really Kill Women?

Ross Pomeroy - April 11, 2019

The Victorian Era corset is a heavy duty clothing apparatus, capable of constricting a person's waist down to a dainty 17 inches. A slim midsection and an hourglass figure were all the rage in 19th century Europe, so women (and undoubtedly a few men) of all ages and social classes donned "tightlaced" corsets to keep the trend.

As science writer Brian Switek wrote in his new book Skeleton Keys: The Secret Life of Bone, this superficial bodily molding led to some cringe-worthy anatomical re-arranging:

"The stomach and liver are crammed down, with the ribs compressed into drooping S-loops. The neural spines of each vertebra, the little projections that stick up from the central body of each bone, are also pushed out of place. Normally they stack nicely one atop the other in a neat midline ridge, but in long-term corset wearers these spindles of bone jut to this side or that."

The practice prompted a public uproar, with doctors penning articles and books decrying corsets as a health "plague," one on the same level as tobacco, gambling, strong drink, and illegal speculation, wrote Charles Dubois. Physicians blamed corsets for causing tuberculosis, cancer, liver disease, heart damage, and a host of other ailments.

Four Fascinating Facts About Kneecaps

Ross Pomeroy - April 2, 2019

The patella, or kneecap, is one of the most incredible bones in your body. As a sesamoid bone, it is embedded within a tendon, where the quadriceps and patellar tendons meet. There, the rounded, triangular bone protects the knee joint and acts like a pulley, allowing the tendon to transmit more force with smoother motion.

Yes despite the kneecap's obvious usefulness today, its evolutionary history is not entirely understood.

"We know almost nothing about what the kneecap did when it first evolved, when both the tendons that held the bone and the bone itself were thinner and not as well developed," paleontologist Brian Switek wrote in his recent book Skeleton Keys. "It may have been a matter of crossing a certain threshold when individuals who just happen to have sesamoid bones at their knees were better able to cope with the stresses of running and, as luck would have it, left more offspring to carry on the trend."

The trend since spread to most four-footed animals, apart from reptiles and marsupials. Birds are also noted for their kneecaps. In the process, the patella has grown into one of the most unique and intriguing bones. Here are four fascinating facts about the kneecap:

Acetaminophen's Surprising Psychoactive Effects

Ross Pomeroy - March 30, 2019

Every day, millions of people turn to acetaminophen, also known as paracetamol – the active ingredient in Tylenol – to dull the occasional ache or pain. That's because few side effects accompany this highly effective over-the-counter drug when taken at recommended doses. A new side effect is starting to come to light, however. Research is now revealing that acetaminophen may subtly influence your emotions.

To relieve pain, acetaminophen works its magic in the brain, but researchers still aren't entirely sure how this trick works – a remarkable fact considering the drug has been available without prescription for sixty years! It may impact an enzyme called cyclooxygenase, or it might modulate humans' endocannabinoid system. Some experts say one or both of these ideas tells the whole story, while others insist we've barely scratched the surface. Regardless, whatever acetaminophen does in the brain also seems to alter how we perceive the world.

One of the earliest and most elucidating studies on the topic was published back in 2010. A team of scientists from a variety of academic institutions in the U.S. found that subjects who took acetaminophen were not as sensitive to emotional pain compared to people given a placebo.

"In two experiments, participants took acetaminophen or placebo daily for 3 weeks," they described. "Doses of acetaminophen reduced reports of social pain on a daily basis."

The Internet Is Full of Incorrect Images of DNA. Here's How to Spot Them.

Ross Pomeroy - March 26, 2019

It's worth mentioning again and again: a tremendous amount of information on the Internet is wrong. This epidemic of incorrectness extends to the very structure of DNA: the double helix. That's right, many of the images of DNA you see online are drawn with errors. Some may have even appeared on RealClearScience! (Whoops.) What would Rosalind Franklin say?

There are three common errors. The first is the direction of the helix. The most common form of DNA (the variety that's found in almost all known life) is called B-DNA, and it twists to the right. This can be very difficult to notice when looking at a single strand of DNA, but it's easy to spot when a correctly drawn helix is directly contrasted with an incorrect one. Look which way the sugar phosphate backbones (the sides of the ladder) are pointed. When DNA is pictured vertically, they should aim up and to the right.

A second error is failing to include DNA's characteristic grooves. Look again at the image to the left. You'll notice a large gap in between the phosphate strands – a major groove – followed by a smaller one – the minor groove. Many illustrators will neglect this pattern and simply draw the strands evenly spaced out.

The final common mistake that mangles otherwise decent images of DNA is the number of base pairs per 360 degree rotation of the helix. There should be ten, but all too often the "rungs" of the DNA ladder are drawn in without thought. The incorrect image below appears to have 48 basepairs per turn! That's way too many!

What Is Brain Waste?

Ross Pomeroy - March 19, 2019

In the past few years, you may have seen alluring headlines like "Healthy lifestyle choices boost brain waste disposal" and "How to optimise your brain's waste disposal system." Enticed, you click to learn that frequent exercise, a proper amount of sleep, and even resting on your side can help your brain clear out waste products, keeping your cognitive functions in tip-top shape. But wait, what is this brain "waste"? And why does your brain produce it in the first place?

Just like you produce and excrete waste products every day, so do your cells. The process of cellular respiration, which extracts energy from sugar, amino acids and fatty acids, creates byproducts like carbon dioxide, water, ammonia, as well as various types of proteins.

Neurons (brain cells) are notorious energy hogs, and thus produce waste in even greater quantities than other bodily cells. Of the refuse they produce, the most concerning are two proteins: amyloid beta and tau. Amyloid beta is infamous for forming the plaques found in the brains of Alzheimer's patients. When misfolded, tau can create tangles that lead cell microtubules to dissassemble, alter neuronal signaling, and cause mitochondrial dysfunction. Tangles of tau are the hallmark of many neurodegenerative diseases.

Luckily, as Maiken Nedergaard of the University of Rochester Medical Center and her colleagues discovered back in 2012, the brain has a mechanism to clear out tau and amyloid waste. It's called the glymphatic system, which Nedergaard endearingly dubbed the "Garbage Truck of the Brain."

Using Pi Is a Gigantic Mistake

Ross Pomeroy - March 14, 2019

It's Pi (π) Day 2019, and across the world, math teachers, students, and number fanatics are no doubt celebrating with colorful circles and delicious pie. Any day in which science and mathematics are acknowledged is worthwhile, but it's also worth mentioning that π itself is "wrong."

Such a harsh indictment of the irrational number representing the ratio of a circle's circumference to its diameter might come as a shock to Lu Chao of China, who, in 2005, memorized and recited 67,890 digits of π. It also will definitely bum out consumers hoping to cash in on all of the punny Pi Day deals at pizzerias and bakeries. (Who doesn't love $3.14 pizzas?) But the criticism is definitely merited in the opinion of Bob Palais, Chair of the Mathematics Department at Utah Valley University.

"I am not questioning [Pi's] irrationality, transcendence, or numerical calculation," he wrote back in 2001," but the choice of the number on which we bestow a symbol conveying deep geometric significance. The proper value, which does deserve all of the reverence and adulation bestowed upon the current impostor, is the number now unfortunately known as 2π."

6.283185... It doesn't roll off the tongue as well as 3.1415926... But let's hear Professor Palais out.

What Is Stupidity?

Ross Pomeroy - March 2, 2019

What is stupidity? Surprisingly enough, it's a question few scientists have grappled with, perhaps out of a desire not to wade into a subject that could so easily offend. After all, the field of intelligence studies is rife with controversy. Still, some have tendered their thoughts.

Evolutionary biologist David Krakauer, President of the Santa Fe Institute, told Nautilus, “Stupidity is using a rule where adding more data doesn’t improve your chances of getting [a problem] right. In fact, it makes it more likely you’ll get it wrong.”

Carlo M. Cipolla, a professor of economic history at the University of California - Berkeley, argued that stupidity is characterized by causing losses to another person or group whilst deriving no gain and even possibly incurring losses yourself.

In one of the few direct empirical studies on stupidity, researchers Balazs Aczel, Bence Palfi, and Zoltan Kekecs distilled a few traits that drive stupidity: overconfidence, ignorance, absentmindedness, impracticality, and an inability to control one's own actions.

The Scientific Breakthrough That Could Upend the Abortion Debate

Ross Pomeroy - February 25, 2019

With New York state easing some restrictions on late-term abortions and Virginia lawmakers proposing to do the same, the abortion debate has reignited across the United States and looks to be a hot-button issue in 2020.

As in the past, the controversy over abortion pits the "pro-choice" view, favoring the autonomy and privacy of women, against the "pro-life" view, insisting that human life should be protected at any stage of development. The script is essentially unchanged, but the influential actors are different. The Supreme Court now has a decidedly conservative bend, making it likely that the justices will reinterpret the law as it was laid down in decisions like Roe v. Wade, Planned Parenthood v. Danforth, and Planned Parenthood v. Casey. Collectively, those three decisions only allow states to restrict abortion rights after a fetus becomes "viable," the point at which it can survive outside the mother's uterus. With current medical care and technology, that fetal age is between 22 and 26 weeks.

But a scientific breakthrough is on the horizon that could irrevocably alter the abortion debate as we know it. That breakthrough is the artificial uterus, which could drastically lower the developmental age at which an unborn baby is viable, potentially to as early as conception itself.

At present, an artificial uterus with the latter capability is firmly in the realm of science fiction and likely will remain that way for some time. However, artificial uteruses capable of shrinking the age of viability to 15 weeks may not be that far off. In 2017, scientists at the Children's Hospital of Philadelphia detailed their artificial womb that permitted premature lambs roughly comparable to 22- to 24-week human fetuses to develop healthily. At the time, the lead researcher, fetal surgeon Alan Flake, expressed to NPR his hopes to test the womb on human fetuses within the next three to five years.

Why Doesn't Beer, Liquor, or Wine Display Calories?

Ross Pomeroy - February 18, 2019

The vast majority of beers, liquors, and wines do not have nutrition labels, but though their calories are invisible to the eye, that doesn't mean they aren't there. A pint of your average IPA contains 250 calories. A glass of red wine holds 125. A shot of whiskey has about 100.

The secret to these drinks' caloric density is alcohol, which boasts seven calories per gram. That's second only to fat at 9 calories per gram, and much higher than protein or carbohydrate, each of which hold four.

So if alcohol is brimming with calories, why aren't they counted out on labels like all other foods and drinks?

The answer comes down to how alcoholic drinks are regulated. Since the end of prohibition, the vast majority of them haven't fallen under the purview of the Food and Drug Administration, but rather the Alcohol and Tobacco Tax and Trade Bureau (TTB). The TTB has never required nutrition labels like those required by the FDA.

The 'Miles Per Gallon' Illusion

Ross Pomeroy - February 14, 2019

Consider the case of two car owners: One is looking to switch their SUV averaging 12 miles per gallon (MPG) to an SUV averaging 14. The other is looking to switch their compact car averaging 30 MPG to a newer model averaging 40. Both individuals drive 10,000 miles per year. Who of these two people would save the most gasoline and money?

Duke University Professors Richard P. Larrick and Jack B. Soll originally posed this scenario back in 2008 in an article published to the journal Science. To many people, the answer might seem obvious: the second individual would save the most, as they are boosting their MPG by 33% (vs. 16.7%) and will be able to travel 10 miles more per gallon (vs. just two). But this is completely wrong, and it just takes some quick math to figure out why.

Dividing 10,000 miles by 12 MPG, we find that the SUV owner currently uses 833 gallons of gasoline per year. Upgrading would reduce that number to 714 gallons, saving 119 gallons. Dividing 10,000 miles by 30 MPG, we learn that the compact car driver burns through 333 gallons per year. A more fuel efficient car would take that down to 250, saving only 83 gallons. For the SUV owner, a measly two miles per gallon makes a huge difference!

Larrick and Soll used this example to expose 'miles per gallon' as an "illusion" – a flawed measure of fuel efficiency. The duo also conducted three different surveys involving over 300 participants, each of which backed their hypothesis that MPG leads people people to underestimate the large fuel and cost savings of upgrading gas-guzzling cars.

How Sex Killed Tyrannosaurus rex

Ross Pomeroy - February 9, 2019

Tyrannosaurus rex, king of the tyrant lizards, may have been the most fearsome land predator to ever exist on planet Earth. Yet despite its lofty position and regal name, T. rex did not live a pampered, kingly lifestyle. True, no other dinosaur species directly predated upon T. rex after it reached the age of two, when an individual would have grown large enough to dissuade any would be attacker, but that doesn't mean that tyrannosaurs cruised through life, succumbing only to death from old age. In reality, life at the top was not a walk in the (Cretaceous) park.

The most obvious source of peril was prey. Tyrannosaurs would try to pick off juvenile, smaller, or sickly dinosaurs, but would still have to reckon with an angry Ankylosaur, Triceratops, or Edmontosaur in the process. A swipe from a clubbed tail could shatter bones, rendering a T. rex unable to hunt and susceptible to starvation. A stab from a horn could result in infection and eventual death. Herbivores may have had to contend with being hunted, but at least they didn't have to do battle every time they wanted a meal.

Infant T. rex suffered the highest mortality, endangered by predators and disease, but upon becoming a juvenile around age two, life was fairly safe, with nearly three-quarters of individuals surviving to their 13th birthday. Here was where things started to get hairy, however

The pre-teens heralded sexual maturity. Combat for mates and nesting sites would turn T. rex against T. rex. Females would also likely experience extreme stress from laying lots of eggs. Between the ages of 13 and 18, mortality for T. rex might have spiked to as high as 23 percent a year. According to Florida State paleontologist Gregory M. Ericksonover half of the known T. rex specimens seem to have died within six years of reaching sexual maturity.

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