Northern Mariana Islands

United States

U.S. Minor Outlying Islands

U.S. Virgin Islands

Guam

American Samoa

Puerto Rico

US & Territories

Sixty-six million years ago, an asteroid wiped out the dinosaurs in a fiery global catastrophe. But we know little about how their successors, the mammals, recovered and took over the world. Now, hidden inside ordinary-looking rocks, an astonishing trove of fossils reveals a dramatic new picture of how rat-sized creatures ballooned in size and began to evolve into the vast array of species—from cheetahs to bats to whales to humans—that rule our planet today.

Amazing fossils reveal how mammals took over after an asteroid wiped out the dinosaurs.

Rise of the Mammals

NOVA Wonders What Are Animals Saying? Hero

From singing whales and squeaking bats to thumping spiders and clicking dolphins, the world is filled with the exotic sounds of our fellow creatures. What are they saying? While we believe language sets us apart, some animals demonstrate they can learn our language—like Chaser the dog, who recognizes hundreds of words, and Kanzi the bonobo, who appears to have a sophisticated understanding of spoken English. But can we decode their own communications? NOVA Wonders follows researchers around the globe who are deciphering an amazing array of clues that reveal how animals share information critical to their survival. Will we one day be able to write the bat dictionary or decode the hidden sign language of chimps? And what can these findings tell us about the roots of our own language?

Can we crack the code of animal communication?

What Are Animals Saying?

(This program is no longer available for online streaming.) A seven-mile-wide asteroid collided with Earth 66 million years ago, triggering a chain of events that coincide with the end of the dinosaurs. But experts have long debated exactly what happened when the asteroid struck and how the giant beasts met their end. Now, scientists have uncovered compelling new clues about the catastrophe—from New Jersey to the wilds of Patagonia—and an international expedition of scientists has drilled into the impact crater off the coast of Mexico, recovering crucial direct evidence of the searing energy and giant tsunami unleashed by the asteroid. Join NOVA as scientists piece together a chillingly precise unfolding of the Earth’s biggest cataclysm, moment by moment, and discover how our early mammalian ancestors managed to survive and repopulate the Earth. (Premiered December 27, 2017)

Experts drill into the impact crater of an asteroid that created a worldwide cataclysm.

Day the Dinosaurs Died

Koch Foundation

NOVA Science Trust Logo

Even before their keepers enter the night house, the indoor enclosure where they sometimes sleep, Oakland Zoo brown bears Rubicon and Truckee know something is up. “They know we’re out here because they can smell us,” says Animal Care Keeper Erin Melroy. “They’re very smart, and they can pick up on the fact that ‘This is different, do I need to be worried?’”Something is different: Today is the day Rubicon and Truckee will be vaccinated against COVID-19. The zoo is among the first of more than 70 animal organizations across the nation to administer donated vaccines from the animal health company Zoetis. The two-dose Zoetis vaccine, based on the COVID-19 spike protein, can be used across many species, from the zoo’s mountain lions and gibbons to its fruit bats and wolves. Rubicon and Truckee are part of a carefully planned vaccination effort that started on June 30 and will continue for the rest of the year, targeting the zoo’s most vulnerable animals.
 

 
 <div class="related"></div>
 

 
 The bears are in good hands. Melroy and her fellow keeper, Brittany Combs, have been working with them for weeks in preparation: letting them get used to the smell of the syringe, having them practice leaning against the mesh of the enclosure to be injected, getting them used to the poke of a capped needle. Today, settling into the dimness of the night house enclosure, the bears willingly present their shoulders and sit through the jab, in return for a reward of ice cream slurped off the scoop. Melroy compares it to the traditional lollipop many kids get after a shot. “No matter how much training we do, we can’t train away the pain,” she says. “We have to let them know it&#x27;s worth it.”Much like at human vaccination sites, Melroy and Combs stand by after the shot and watch their charge for 10 minutes, keeping an eye out for a swollen muzzle, vomiting, or difficulty breathing. Vice President of Veterinary Services Alex Herman is also on hand in case of emergency, with a box full of Benadryl and prednisone for potential allergic reactions, even though the only documented side effect from the vaccine so far is a gorilla with a headache. (Evident, apparently, from a very specific facial expression.) After the 10 minutes are up, Melroy emerges victorious from the night house. “I didn’t get ice cream with my vaccine,” she says.Herman smiles as she puts away her kit. “I think I got a ‘Neeeext!’”
 <figure class="richtext-image full-width"><img alt="Tiger getting vaccine shot through metal cage" class="richtext-image full-width" height="449" width="800"
 src="https://www.pbs.org/wgbh/nova/media/images/Ginger_Tiger_First_VaccineOakland_Zoo.width-800.png"/><figcaption>A tiger named Ginger receives her first dose of a COVID-19 vaccine at Oakland Zoo in July 2021. Photo courtesy of Oakland Zoo.<div class="credit"></div></figcaption>
 </figure>
 Herman, who has worked at the Oakland Zoo for close to 17 years, realized early in the pandemic that she and her colleagues would need to take action to protect the animals under their care. Knowing that the virus likely came from bats, she was already on her guard; then news broke in April 2020 that several <a href="https://www.nationalgeographic.com/animals/article/tiger-coronavirus-covid19-positive-test-bronx-zoo">lions and tigers</a> had gotten sick at the Bronx Zoo. Luckily, none of the Oakland Zoo’s animals has developed any symptoms so far. Herman credits the additional barriers the zoo put around ape enclosures and the personal protective equipment staff wear during training, treatments, and food preparation.
 

 
 Meanwhile, on the other side of the country, Zoetis was also on alert. The company usually focuses on domesticated animals like cats and dogs. But as the virus spread in <a href="https://www.pbs.org/wgbh/nova/article/mink-covid-virus-mutation/">Denmark’s mink farms</a> and prompted that country to <a href="https://www.reuters.com/article/health-coronavirus-denmark-mink/denmark-incinerates-4-million-mink-culled-to-curb-covid-19-mutations-idUSL3N2NF1YZ">cull millions</a> of the animals, Mahesh Kumar, Zoetis’ senior vice president of global biologics, started to think again. When, in November 2020, the Department of Agriculture (which oversees animal vaccines in the U.S.) published a notice that it would consider applications for a COVID-19 mink vaccine, they decided to switch focus. Zoetis had already developed vaccines against coronaviruses for multiple species, experience that helped them narrow down their options. Kumar’s team knew immediately they wanted to avoid the extra time and regulatory hurdles that would come with an mRNA vaccine, as well as the health risks of working with live viruses. “In half an hour we could make the call,” Kumar says. They drew up a plan to develop a vaccine containing non-functional pieces of the virus, the SARS-CoV-2 spike protein, which would be synthesized in a lab. That decision ruled out non-injection delivery methods that require a live virus to work, like nasal sprays. (That might not have been realistic anyway. “Imagine trying to give a cat a nose spray vaccine,” Kumar says.) 
 

 
 <div class="ad"></div>
 

 
 Though the Zoetis vaccine was tested on dogs and cats and is being developed for mink, Kumar says it’s quite common, and in fact expected, for zoos to use vaccines off-label for other animals, with the approval of veterinary authorities. The vaccine’s two-dose regimen makes up for variability between animals and hopefully assures that animals of all sizes will get “enough” vaccine, from a grizzly bear to a red-tailed monkey. The zoo’s initial shipment from Zoetis provides 50 double doses, covering about half of the 110 animals Herman has identified as in need of vaccination. Another shipment due in August will cover the rest. She and her staff worked mostly off clinical evidence—documented cases where a species or related species was infected—to make that list, which includes bears, Old World monkeys, hyenas, river otters, meerkats, wolves, and big cats like jaguars, lions, and tigers. She also plans to vaccinate the zoo&#x27;s two types of fruit bats, even though bats are famously able to harbor many types of viruses without getting sick. “We’re aware they could maybe asymptomatically harbor different variants,” she says. Risking passing the virus back to staff is out of the question.In a process similar to the emergency authorization given for human COVID-19 vaccines, once Zoetis demonstrated antibody response in vaccinated dogs and cats, the USDA awarded the company a conditional license to manufacture the experimental doses. For full authorization, Zoetis will also need to do “challenge testing,” which involves purposefully infecting test subjects with the SARS-CoV-2 virus, as well as “field trial” testing in commercial mink facilities. But for now, Kumar is pleased that his still-experimental vaccine will be helping animals across the country. “It’s important to understand, when you develop a vaccine in such a rapid manner that it’s not always a slam dunk,” he says. “We’re fortunate and thankful that we had this expertise and lucky it came together.”
 <figure class="richtext-image full-width"><img alt="Human holding ferret getting a shot" class="richtext-image full-width" height="650" width="800"
 src="https://www.pbs.org/wgbh/nova/media/images/Archie_Ferret_Vaccine_-_ferret_vitamin_supplem.width-800.jpg"/><figcaption>Archie the ferret licks a vitamin supplement while receiving his first dose of a COVID-19 vaccine at Oakland Zoo in July 2021. Photo courtesy of Oakland Zoo.<div class="credit"></div></figcaption>
 </figure>
 After they identified their target species, Herman and her colleagues looked at the animals’ preferences to help plan their vaccine schedule. Because the zoo’s medical procedures are based on the animals’ willing participation, veterinary staff spend significant time tracking behaviors, gauging when an individual will be most receptive. The elderly tigers, for example, have blood taken frequently to help with monitoring and treatment of their kidney disease. The staff have noticed that “the older tiger ladies like something like 8:30 in the morning,” Herman says, while one mountain lion prefers after lunch, and the “lion boys”—a group of rambunctious teenagers who hang out together—are more likely to cooperate mid-afternoon. 
 

 
 Zoological Manager Andrea Gibson worked for weeks with a group of native Californian animals, including gray wolves, brown bears, black bears, and a jaguar, to get them ready for vaccination. Tolerating shots was a behavior they’d worked on before, since zoo animals need to be vaccinated often against diseases like rabies and distemper. Getting animal buy-in and not needing to fight against aggression or fear is key, she says. “It makes it easier on them, makes it easier on us, and they get a lot of rewards for doing it.”Training for a vaccination usually entails breaking down the behavior into small steps and rewarding the animal for each success. For the larger carnivores, that usually means sitting quietly and presenting a shoulder or hip against the mesh of the enclosure, so a vet tech can reach it from the other side. (“It goes right into that muscle, like with humans,” Gibson says.) The animals get rewards for sitting; for leaning into the mesh; and for staying still during “sensitization”—in which they get used to a finger, then a closed syringe, then a needle touching their skin or fur.In the case of the COVID vaccine, the animals also needed to acclimate to the presence of a new person (the vet tech, brought in to handle the vaccine itself) and the personal protective equipment staff needed to wear that might make them seem scary: goggles, facemask, gloves. At each step, the keeper used a signal or “behavior bridge,” in this case a whistle, to let the animal know it did a good thing and a reward was coming.During normal training, that reward might be a tasty but standard item from an animal’s diet, but today is a special occasion. That means each successful animal gets a “jackpot” treat, or a snack of its most favorite food. Mountain lions get goat milk squirted into their mouths; Rubicon and Truckee the bears get their ice cream; Moses the alpha chimpanzee opts for M&amp;M’s. 
 <figure class="richtext-image full-width"><img alt="Two black apes lay in grass" class="richtext-image full-width" height="533" width="800"
 src="https://www.pbs.org/wgbh/nova/media/images/Ganesha_and_Hahnumahn_Siamangs_Oakland_Zoo.width-800.jpg"/><figcaption>Siamang brothers Ganesha and Hahnumahn lounge in their habitat at Oakland Zoo. The pair received their first doses of a COVID-19 vaccine in July 2021. Photo courtesy of Oakland Zoo.<div class="credit"></div></figcaption>
 </figure>
 Ganesha and Hahnumahn are Oakland Zoo’s siamangs, mid-sized ape brothers with exceptionally long arms. They live on a lush island in the middle of a small green pond and do everything together: eating, sleeping, playing. Their keepers have even arranged for them to be vaccinated on separate days so they can care for each other. 
 

 
 Today it’s Ganesha’s turn. His brother keeps him company inside their night house as the vet tech and keepers prepare, chattering to him throughout the procedure. Ganesha’s reward is a giant marshmallow, which he eats in several dainty bites. After watching for any allergic reactions, the keepers open the night house door, and the two apes shamble across the wooden plank that serves as a bridge to their island, then settle in for a lazy afternoon munching vegetables and greenery. As she prepares for her afternoon vaccinations—the “lion boy” teenagers are up next—Herman reflects on the role zoos have to play in conservation and education during a multispecies pandemic. For Oakland Zoo, she says, the key is a philosophy known as One Health, which sees human and animal health as intimately linked, so “to protect one is to protect the other.”The primary goal of these vaccinations may be to protect her animals, she says, but “any advantages that flow from that are great.” That includes both educating the public about conservation and ecology and protecting it from disease. “We’re a conservation organization,” she adds, “and what that means is that all the beings on this planet, wildlife and the environment all need to be cared for because we’re all so interconnected.”  
 

 
 <div class="newsletter"></div>

Young male lions at Oakland Zoo. Image Credit: Steven Gotz, Getty Images

Lions and tigers and bears have been training for this moment (and it’s pretty cute).

Oakland Zoo vaccinates its animals against Covid-19

Step One: Start paying attention to the birds in your area.
New York City Audubon&#x27;s Christian Cooper shares stories of his early days as a birdwatcher, and offers suggestions on how to get involved in birding and make it more accessible in your community.
How to Make Birdwatching More InclusivePublished: June 8, 2021Christian Cooper: My dad was a biology teacher, so nature was always big in our household you know, in some form or another. For some reason, my parents decided I needed to do the 4H program one summer, which is where you build things out of wood. I had zero interest, but I had to choose whether I was going to build a footstool or a bird feeder. And I was like, “Alright, I guess I&#x27;m building the bird feeder.” So I built that.And when it was done, I put it in the backyard, filled it up with seeds and all these birds kept coming and I got really interested, including this one bird. And I thought I had discovered a new species because it was a crow with these big red patches on the shoulder of the wing. And I was like, “Oh my God. I found a new species of crow.” Of course, it turned out it was a redwing blackbird. But, you know, I was little. What did I know? I learned eventually.And then right around that same time, both my parents were teachers so they had the summers off. They packed me and my sister and themselves and the family cocker spaniel into a Volkswagen VW camper cramped thing for three months of the summer, going cross-country camping. We didn&#x27;t have a lot of room and we couldn&#x27;t bring a lot but one of the things my dad brought, as a biology teacher, was a field guide to the birds. So, you know, a lot of driving, a lot of hours passing through cornfields, not a lot to do.So I was flipping through one of the few books we had. And, you know, I had a pretty good memory back then not a lot else to cram things out of it. So by the time we got to the West Coast, a bird would fly by and I’d go, “Oh, look, Mom and Dad, there goes a magpie.” And they’re like, “How in the hell does he know that?” Because I remembered it from the book. So the combination of those two things just kind of sparked the interest.You know, if someone of color does show up at your bird walk. At your Audobon society or whatever group it is that is into the outdoors, make them feel welcome, make sure they know that they belong. I&#x27;ve been trying to get kids in underserved areas exposed to birding and birds in the outdoors.A lot of these kids don&#x27;t think in those ways. They don&#x27;t think that that&#x27;s accessible to them. They don&#x27;t think that it&#x27;s something that they should be involved in. And I&#x27;d like to get them out there and show them, “Hey, look, this is yours, too, and it&#x27;s here in your backyard, you know.” Some of them live right on Central Park, which is an amazing birding spot. Others of them may just have some little pocket park, but there&#x27;s birds there, too. You&#x27;ve just got to try to tune into it.Just start paying attention. That&#x27;s the first step. Whether you have binoculars or not find a water source in your whatever little patch of ground it is and just plant yourself there and watch for a while and see what comes by to bathe and to drink and try to figure out what you&#x27;re seeing. Are they the same kind of bird? Or are they male and female? And then you&#x27;re going to want to get your hands on binoculars, and also a field guide to help you sort these things out. Maybe you know somebody who has a pair of binoculars, who’s getting rid of them, because they’re upgrading. Take them. Even without them you can start birding.

How to Make Birdwatching More Inclusive Hero

Step One: Start paying attention to the birds in your area.

How to Make Birdwatching More Inclusive

Join NOVA producer Arlo Pérez as he unlearns a “fact” he was taught as a child.
Discover a piece of false information about monarch butterflies and Mexico’s Indigenous Purépecha community, and why tourism may be partly to blame.
The Big Lie about Monarch ButterfliesPublished: March 16, 2021Arlo Pérez: The problem with misinformation is that you don&#x27;t realize it&#x27;s wrong until you&#x27;ve made a complete fool of yourself. That&#x27;s what happened to me. I&#x27;ve been making a video about the monarch butterflies, the iconic insect that migrates from parts of Canada all the way to Michoacán in Western Mexico, where I grew up. To do so, I&#x27;m on my way to meet Teresa Madrigal, a prominent member of the Purépecha, an Indigenous community in the area.(Translated from Spanish): Hello! Miss Teresa?I&#x27;m interested in speaking with Teresa because I&#x27;d always heard that monarchs were incredibly important for the Purépecha.Maria Teresa Madrigal Martínez: (Translated from Spanish) There are only a few Purépecha kitchens left.And that the butterfly&#x27;s yearly return to Michoacán signifies the reincarnation of the Purépechas&#x27; ancestors&#x27; souls. Unfortunately, Teresa is about to inform me that the story that I&#x27;ve been working on for four months is wrong.Madrigal Martínez: (Translated from Spanish) I&#x27;ve never seen them. I don&#x27;t even know them.Pérez: (Translated from Spanish) And you haven&#x27;t seen one?Madrigal Martínez: (Translated from Spanish) No, I don&#x27;t even know them. Maybe on a painting.Carlos García Mora: (Translated from Spanish) No, no, no, no, no, no.Pérez: And she is not the only one.García Mora: (Translated from Spanish) No. Of course, it is not the monarchs.Benjamín Lucas Juárez: (Translated from Spanish) The butterflies are not within the Purépecha territory.García Mora: (Translated from Spanish) Eh, just no.Pérez: Turns out, this belief belongs to completely different Indigenous communities, including at least two that are closer to the forest where the monarchs winter. But here&#x27;s the thing: I remember learning about the Purépecha and the monarchs in school only 45 minutes away from here. And I have seen this incorrect piece of information pop up in a bunch of different publications, both from the U.S. and from Mexico.And that got me thinking, how did this weirdly specific bit of misinformation get propagated?Juárez: (Translated from Spanish) After the Revolution, Mexico had to rebuild itself as a country.Pérez: This is Benjamin Lucas Juarez, historian of Purépecha descent, who dedicated his life to studying the Purépecha culture. And he&#x27;s talking about the 1910 Mexican Revolution.Juárez: (Translated from Spanish) While trying to build itself as a country, it was important to use symbols that unified the Mexican identity. I&#x27;m talking about the pyramids, the Aztecs, the Mayas, as a way to reclaim their past. But also to unify the country&#x27;s cultural identity into one or two cultures. In other words, one where there are no differences, no Indigenous languages, no different clothing, no different celebrations/Pérez: Just one unifying Mexican identity. But in a country with over 65 Indigenous communities, and more than 360 languages, this unification would come at the cost of placing few cultures center-stage while pushing everyone else into obscurity.Madrigal Martínez: (Translated from Spanish) &quot;Don&#x27;t speak any Purépecha so you can speak Spanish.&quot; That&#x27;s what our teachers would say.Pérez: And as a result, those cultures become more difficult for historians to study.David Carballo: We don&#x27;t have the detail for Purépecha culture, that same level as, say, we do Mayans and the Aztecs.Pérez: On top of the relative anonymity...Madrigal Martínez: (Translated from Spanish) Look at my uncle&#x27;s beautiful mask!Pérez: and the sparse study of these Indigenous communities...Madrigal Martínez: (Translated from Spanish) He would dance a lot.Pérez: many of them pass down their ideas through symbols and unwritten traditions. The problem is, these can end up being misinterpreted by outsiders.Archival footage #1: Lake Patzcuaro is about 250 miles west of Mexico City.Pérez: More often than not...Archival footage #1:The island fishermen live in primitive adobe buildings centuries old.Pérez: people on the outside have failed to understand the complexity of these traditions, and how they might differ among multiple Indigenous cultures.Archival footage #1: Most primitive people all over the world stopped using the throwing stick when the bow and arrow was discovered. But here on this beautiful lake in Mexico, it is still used every day.Pérez: And it is from this outside and uninformed perspective that the misinformation about monarch butterflies might have originated.Archival footage #2: And so, these are the creations of the magic hands of Mexico.Carballo: I mean, I think it starts with tourism.Juárez: (Translated from Spanish) These are the types of mistakes that are made in promoting tourism.Archival footage #2: These hands are not limited by age or gender. They know only one thing: how to create beauty.Carlos García Mora: (Translated from Spanish) Often the people who create tourist information are not familiar with the regions they write about. And their touristic propaganda spreads misinformation.Archival footage #2: Centuries ago, the ancient Maya realized the mesmerizing power of silver.Carballo: A tourist-focused process, it doesn&#x27;t care so much about authenticity. It cares about just aggregating imagined realities of those people.Juárez: (Translated from Spanish) The institutions in charge of promoting tourism take the elements as something they can sell, something that can be exploited.Archival footage #2: The magic hands of Mexico find beauty in everything. Most of all, in sharing that beauty with you.Juárez: (Translated from Spanish) And that is what they have promoted. &quot;Come and see the spectacle.&quot;Madrigal Martínez: (Translated from Spanish) Over here, look. My sister, the oldest. She is the one that passed away.Pérez: This is still happening today. Take the Day of the Dead, &quot;el Dia de los Muertos,&quot; as an example. Traditionally, it&#x27;s a day when family and friends gather to remember those who have died. But over time, it&#x27;s become a huge spectacle.And in 2016, Mexico City adopted a yearly Day of the Dead parade, copying a fictitious parade featured in the James Bond film &quot;Spectre&quot;. A completely new tradition created by the imagination of foreigners.Juárez: (Translated from Spanish) This phenomenon of &quot;touristification&quot; is risky because it brings an economic activity that is more profitable than their own tradition, eroding their own cultural elements.Pérez: Which is why understanding, and ultimately respecting, unique traditions is so important.So let&#x27;s get the facts right. The Purépecha do use butterflies as a way to think about the afterlife. But not the monarchs. Theirs are butterflies that are small and white.Madrigal Martínez: (Translated from Spanish) What I would play with when I was a little girl were little white butterflies. And that they would say was the soul of the children.Pérez: But it&#x27;s not just swapping monarchs for white butterflies. It is a completely different and more nuanced way of viewing the dead.Juárez: (Translated from Spanish) The view the Purépecha have is that people die. But they also believe that their soul, their essence, keeps on living. But not like an abstract entity. But rather their presence can be felt within the fire, within the air...Pérez: or as butterflies.Juárez: (Translated from Spanish) These butterflies flutter near where the kids play. The grandparents tell them not to scare them away because they are souls. But this is a communication, a very didactic way of familiarizing children with taking care of nature. For them to understand that souls can be understood this way, as subtle, but as present as though they were butterflies.Pérez: For the Purépecha, the dead remain constantly present, encountered in nature all around us. To explain this belief, the Purépecha turn to these small white butterflies and other natural phenomena.Now, misunderstandings aren&#x27;t exclusive to Mexico. Many would argue that lots of modern communities all around the world have their own misconceptions about Indigenous cultures. But that in itself just raises the question. How many more of these cultural misconceptions are out there and what can we do to prevent them?Carballo: By including indigenous voices today in understanding the deep history of the Americas, we get not only a more accurate understanding but one that reflects all of the diversity and the different perspectives of native peoples who&#x27;ve inhabited this hemisphere for thousands of years.Madrigal Martínez: (Translated from Spanish) Without our customs, our community would be dead. We have many beautiful things in our little communities. Many, many beautiful things. It&#x27;s an honor being Purépecha.

The Big Lie about Monarch Butterflies Hero

Join NOVA producer Arlo Pérez as he unlearns a “fact” he was taught as a child.

The Big Lie about Monarch Butterflies

Image Credit: Gallinago_media, Shutterstock

In the past year, millions of the animals have been culled to stop the spread of COVID-19 on mink farms across Europe. But this is more than just a fur coat crisis.

What’s the deal with mink Covid?

Hear from two scientists trying to hack photosynthesis.
RUBISCO, which helps make photosynthesis happen, is the most plentiful enzyme on the planet. But it&#x27;s not the most efficient. Can a team of researchers give it a boost?
Meet the Enzyme Driving PhotosynthesisPublished: February 22, 2021David Pogue: Usually you hear about efficiency, like of a gas engine, measured in terms of percentage, how much fuel is ultimately converted to energy. What’s the percentage efficiency for a plant?Lisa Ainsworth: Well, in terms of how much of the light energy it turns into sugar, it’s pretty low maybe around three percent%.David Pogue: Three percent? That’s terrible. .Lisa Ainsworth: That’s the plan.David Pogue: To improve photosynthesis, two researchers, Amanda Cavanagh and Paul South, have focused on one of its key molecules. It has a very catchy name.Amanda Cavanagh: So the molecule is what we biologists call an enzyme. And so it does the work. Enzymes are like biological workers. And the enzyme’s called RUBISCO.Paul South: It’s RUBP, or ribulose bisphosphate carboxylase oxygenase.Amanda Cavanagh: And it’s, for most plant biologists, one of our favorite enzymes on the planet.Paul South: Yeah RUBISCO is our shortened term for it.David Pogue: Mainly because it’s fun to say.Amanda Cavanagh: Well it’s super fun to say.David Pogue: RUBISCO.Amanda Cavanagh: Of course. RUBISCO. But, it is also a really cool enzyme because it makes life on Earth possible.David Pogue: RUBISCO may not look so special but it is arguably the most important enzyme on the planet because of its critical role in photosynthesis. RUBISCO’s job is to grab a molecule of carbon dioxide and feed it into a molecular machine that’s building carbon chains. That means, any carbon atom, that’s part of any plant anywhere got there thanks to RUBISCO, or one of its close variants. And because we eat plants or animals that ate plants that also includes just about every carbon atom in your body—all approximately eight hundred, million, billion, billion of them. That’s 26 zeroes. Not bad RUBISCO, not bad.Paul South: Yeah so if it’s ever come from a plant, it had to have gone through that enzyme of RUBISCO.David Pogue: That’s wild. How come there’s not a memorial to RUBISCO in Washington? It seems like, sort of important.RUBISCO is important and that’s why it’s the most plentiful protein on Earth. But just because you’re important, doesn’t mean you’re entirely competent.Paul South: It’s, in this case, not the best enzyme in the world.Amanda Cavanagh: It’s got a hard job, so it’s doing its best, but at the same time it exists in an atmosphere that’s not predominantly carbon dioxide, it’s mostly oxygen.Paul South: And about one in every four or five reactions it grabs oxygen instead of carbon dioxide.David Pogue: That’s right. RUBISCO screws up about a fifth of the time. Instead of attaching a carbon dioxide, it attaches an oxygen molecule. And that’s trouble.You’re saying nature has created a screwed-up little worker enzyme?Paul South: Yeah so 400 million years ago, when this enzyme evolved, there wasn’t very much oxygen in the air.David Pogue: All right. So I’m the little RUBISCO enzyme and like on the conveyor belt here. And like carbon dioxide, carbon dioxide, carbon dioxide, carbon dioxide, oxygen and I- I don’t notice I accidentally grabbed oxygen out of the box.Paul South: And it produces compounds that are inhibitory to photosynthesis, so it kind of starts to shut things down.David Pogue: I mean it’s been going on for billions of years and nobody has cared.Amanda Cavanagh: Yeah, well..David Pogue: I mean, it all basically works.Amanda Cavanagh: Photosynthesis right now is sort of a victim of its own success, RUBISCO certainly is. So by oxygenating the atmosphere via photosynthesis, you now have a huge amount of oxygen in the atmosphere but you need a carbon dioxide to make the reaction work.David Pogue: So what happens when RUBISCO screws up? The result gets shipped out through a couple other parts of the cell to where the mess is taken apart and recycled, all of which consumes a lot of energy.So, if you could fix this inefficiency problem, the plant might make more soybeans, corn, whatever it is?Amanda Cavanagh: That’s exactly it. Then they will have that energy to put towards something that we will consider useful like making more food for us to eat.David Pogue: Is this just a crazy theory or is this some indication that this could actually work.Amanda Cavanagh: There is quite a bit of evidence that this is working. So right now, we have this tested in a couple of model species.David Pogue: It is tropical in here.Amanda and Paul take me to the greenhouse to see one example. Using two genes one from algae and the other from a pumpkin, they’ve modified tobacco plants to address RUBISCO’s “sloppy work.”And why are we using tobacco plants?Amanda Cavanagh: Yeah tobacco’s a really useful model crop for us.David Pogue: Why tobacco? Turns out it’s one of the easiest plants to genetically manipulate which makes it a common test subject.Paul South: They have definitely shown improvements in plant growth and total biomass, and we’ve been studying the rates of photosynthesis, and we are pretty confident now that our model crop is successful in this pathway, and now we’re really interested in moving these into something we like to eat.David Pogue: Reducing the energy penalty crops pay for RUBISCO’s mistakes could be huge. In soybeans, a 25% reduction could result in plants that produce more than 60 million more bushels a year.Amanda Cavanagh: This to a lot of people is an idea that might be out there, but if we can get it, if we can get this moonshot approach to work, then we’re going to have more food. And so that’s really what drives what I do.

Meet the Enzyme Driving Photosynthesis Hero

Hear from two scientists trying to hack photosynthesis.

Meet the Enzyme Driving Photosynthesis

A few months after competing in the 2008 Summer Olympics in Beijing, Norweigian horseback rider Tony André Hansen was stripped of his bronze medal. His horse Camiro had failed a drug test during the Games, testing positive for capsaicin. The International Equestrian Federation <a href="https://www.nytimes.com/2008/08/22/sports/olympics/22doping.html">dismissed the pair</a>, along with three other showjumping riders and horses, from the competition. Hansen has not competed in the show ring since.Capsaicin is the chemical responsible for the “heat” in chile peppers. Like many over-the-counter muscle rubs—think “IcyHot”—capsaicin can bring on both tingling sensitivity and numbness.
 

 
 <div class="related"></div>
 

 
 When applied as a <a href="https://www.reuters.com/article/us-olympics-equestrian-doping/norway-bronze-medalist-suspended-idUSPEK303420080821">paste or lotion to horses’ forelegs</a>, capsaicin can cause a burning sensation that would be exacerbated by knocking against the rails of a jump. If a showjumping horse lifts its legs higher, it avoids the potentially irritating touch of a fence—and its rider avoids incurring penalties. But capsaicin can also soothe aches and pains by temporarily <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6006555/">deactivating the nerve endings</a> where it’s applied. An exhausted horse with numbed nerves will perform better than an equally tired one that can feel the full pain of its aching muscles, according to the <a href="https://aaep.org/horsehealth/lameness-and-poor-performance-sport-horse-eventing">American Association of Equine Practitioners</a>, which is why capsaicin is banned from equestrian competitions to this day. “Capsaicin binds to the TRPV-1 receptor—a pain receptor present all over our bodies,” says Ivette Guzmán, a horticulturist and member of the Chile Pepper Institute of New Mexico State University. If a horse is sore, “applying capsaicin binds up those pain receptors,” she says. A horse may feel a little bit of heat from topical capsaicin, but “they won’t feel the pain,” Guzmán explains. “It works on us, too.”Just as horses experience a numbing feeling from a topical application of capsaicin, your tongue will tingle when you chew a hot pepper. This numbing sensation is often coupled with a burning one that’s enjoyed by spicy food-lovers around the world: Whether eating centuries-old cuisines like <a href="https://www.theatlantic.com/health/archive/2019/04/why-we-call-indian-dishes-curry-colonial-history/586828/">Indian curry</a> or saucy chicken wings on the popular YouTube series “Hot Ones,” human beings have subjected themselves to the uncomfortable chemistry of capsaicin <a href="http://sitn.hms.harvard.edu/flash/2012/issue131b/">for millennia</a>.<h3>The need for heat</h3>Pepper species native to the Americas fall within the genus Capsicum. Some Capsicum peppers, like the mild bell pepper, have no capsaicin at all. Others, like the jalapeño and habanero pepper—popular additions to dishes requiring some extra “heat”—do have the chemical. (A few Capsicum peppers, including the incredibly-hot ghost pepper, were developed in South Asia by hybridizing varieties from the Americas.)“A lot of people mistakenly think the seeds are what hold the spice,” Guzmán says. But “capsaicin is found in the part of the fruit called the placenta: the membrane that holds onto the seeds.”But spicy food doesn’t have to be hot to convey heat. In fact, capsaicin doesn’t physically burn your tongue and innards at all. When your body processes capsaicin, your nervous system sends out a response that activates your senses for touch and temperature. The same receptors responsible for blocking topical pain send signals to your brain that you’re being burned when you eat something spicy. And here’s the kick: Capsaicin alters the sensitivity of the pain receptors in your mouth, effectively lowering the temperature at which you feel burning pain. This is why jalapeño sauce feels burning hot even after being refrigerated.“These [receptors] work really well when they detect the correct stimulus,” says Joanna Buckley, a chemist at the University of Sheffield in England. “They respond to anything over 43 C (109 F). So if you have a hot cup of tea, this receptor will work correctly and tell you, ‘Oh, your tea’s a bit hot.’” The problem is, Buckley adds, these heat-sensing receptors are also triggered by a class of compounds called vanilloids. Capsaicin is one of them.
 

 
 

<div class='cove-video'>
 <iframe allowfullscreen="" class="inline-cove-player" frameborder="0" height="100%" id="partnerPlayer" marginheight="0" marginwidth="0" scrolling="no" src="//player.pbs.org/partnerplayer/oqcBDm0F49udaZUIkmE3Fg==/?topbar=false&amp;end=0&amp;endscreen=true&amp;start=0&amp;autoplay=false" width="100%">
</iframe>
</div>


 

 
 Chemically, capsaicin is corrosive (like hydrogen peroxide), acutely toxic (like chlorine), and irritating (like ammonia). And its irritant qualities won’t just fire up your mouth: Capsaicin can have a similar effect on other mucous membranes. If you’ve ever chopped peppers and then accidentally touched your eye, you understand how irritating this compound can be. So why do some people enjoy—and even get a thrill out of—eating a fruit with such a kick?“We get interviewed often by chiliheads,” Guzmán says. “I’m Mexican. I grew up eating jalapeños, I grew up eating really spicy food, and I understand that there are other chemicals in [peppers] that are medicinal. But when it comes to chiliheads, I think they’re fascinated by the chemistry of capsaicin and how it makes you feel something you’ve never felt before. It gives you a euphoria.” Measuring that euphoria depends on the Scoville scale.<h3>Let’s talk Scovilles</h3>Named for American pharmacist Wilbur Scoville, <a href="https://www.vox.com/2016/1/22/10810564/wilbur-scoville-google-doodle">the Scoville scale</a> ranks the pungency of chile peppers based on the concentration of capsaicin in the pepper. It’s this concentration that determines how our bodies will react to peppers; while small amounts of capsaicin fall within the “spicy chicken dinner” category, stronger concentrations spell out “weapon-grade pepper spray.” In the early 1900s, Scoville, who was working as a chemist at the time, attempted to test out people’s relative capsaicin tolerance. He recruited five human subjects to taste-test mixtures of dried pepper and sugar water and had them report how hot they found each mixture to be. The basis of his heat scale is the amount of sugar water needed to dilute the mixture enough for the majority of his subjects to no longer feel the heat. These days, a technique called high-performance liquid chromatography is used to determine exactly how much capsaicin a pepper contains in parts per million, and multiplying the result by 16 converts it to <a href="https://www.smithsonianmag.com/arts-culture/how-hot-is-that-pepper-how-scientists-measure-spiciness-884380/">Scoville Heat Units (SHUs)</a>.
 

 
 <div class="ad"></div>
 

 
 The highest level of naturally occuring capsaicin is in the Carolina Reaper, the hottest pepper in the world. Its creator, chile pepper grower Ed Currie, bred the pepper by taking one uniquely spicy <a href="https://www.palmettobluff.com/discover/fear-the-reaper">habanero</a> grown on the La Soufrière volcano on Saint Vincent in the Caribbean and crossing it with a Naga Viper pepper, which was developed in the United Kingdom from peppers hailing from the Caribbean and South Asia. The hottest single Carolina Reaper ever to be harvested rang in at 2.2 million SHU, meaning that more than a tenth of the pepper was pure capsaicin.High amounts of capsaicin, like those found in the Carolina Reaper, can cause injury. “Capsaicin is a really potent chemical. If you have too much of it, it can be toxic,” Buckley says. “It’s the thing that’s used in pepper spray. We’ve all seen images of people who have been pepper sprayed. Their eyes are swollen up, they’re crying, they can’t see…so it’s incredibly important to know how to handle capsaicin” safely, she says.<h3>Your body’s battle against spice</h3>If you don’t welcome spicy burns, there’s a way to neutralize the compound’s effects: dairy. “Capsaicin is an oil and it is insoluble in cold water,” Buckley says. Though it’s somewhat soluble in alcohol, like beer, Buckley explains, capsaicin is best dissolved by another oil. “You need to find something that’s fatty to dissolve the capsaicin,” she says. “That’s why the best thing to drink is milk.” Although spicy food is sometimes associated with stomach problems—Currie, who not only created the Carolina Reaper but also eats one every day, still <a href="https://www.latimes.com/nation/la-na-reaper-pepper-20141127-story.html#">experiences severe stomach cramps</a>—there is no direct evidence that spicy food causes belly cramps or nausea. The perceived pain, Guzmán explains, may just be a side effect of your gut membranes being irritated. While a 2016 study showed capsaicin can cause those with abdominal disorders to experience <a href="https://pubmed.ncbi.nlm.nih.gov/27094759/">flare-ups in their symptoms,</a> the same can be said for <a href="https://www.pbs.org/wgbh/nova/article/unless-you-have-celiac-disease-gluten-sensitivity-is-probably-just-in-your-head/">too much bread</a>, a famously unspicy food.But there are always worst-case scenarios.
 <figure class="richtext-image full-width"><img alt="Trinidad scorpion pepper" class="richtext-image full-width" height="450" width="800"
 src="https://www.pbs.org/wgbh/nova/media/images/Trinidad_Scorpion_Pepper.width-800.jpg"/><figcaption>A Trinidad moruga scorpion pepper, which is currently the second hottest pepper in the world to the Carolina reaper. Image credit: John Vonderlin, Flickr<div class="credit"></div></figcaption>
 </figure>
 More than 150 different varieties of chile grow in a garden at New Mexico State University’s Chile Pepper Institute. “One year we had a group of students we were doing a tour with in the garden. And one student thought it would be funny if he bit a tiny piece off a Trinidad Scorpion pepper,” Guzmán says. “He did that, and he threw up in the garden, and he passed out, and we had to carry him to a shaded area under some trees.” Because capsaicin is a toxin, Guzmán explains, the human body’s first response to an excess of it is to flush it out. (In the student’s case, by vomiting.) In 2018, the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5893965/">National Institutes of Health reported</a> that a previously healthy 34-year-old man was admitted to the hospital with “thunderclap headaches”—sudden, severe head pain accompanied by fever, blurred vision, and even seizures—after eating a Carolina Reaper whole. Doctors treated him by flushing the capsaicin out of his body, which, like many chemical compounds in large amounts, can be dangerous. Of course, Olympic equestrian Tony André Hansen’s story shows that even a small amount of this complex compound can be damaging (and in some cases, even career-ruining). It just depends on where—or upon whom—the capsaicin ends up.
 

 
 <div class="newsletter"></div>

Red hot chili peppers, and other hot peppers within the Capsicum genus, get their heat from the chemical capsaicin. Image credit: Austin Kirk, Flickr

Discover capsaicin, the active ingredient in chile peppers. (If you can take the heat.)

From jumping horses to jalapeños: the science of spicy peppers

What’s in this snail’s paralyzing venom?
Scientists explore how the powerful peptides found in marine cone snail venom can be used for medicinal and therapeutic purposes.
How Killer Snail Venom Plays a Key Role in Drug DevelopmentPublished: February 11, 2021David Pogue: Time to meet my first Professor of Venoms, Mandë Holford, of Hunter College. Now, I couldn’t help noticing, there’s a huge, terrifying tarantula on me. Is she poisonous?Mandë Holford: No, no, she’s not poisonous.Pogue: Oh, whew!Holford: She is, however, venomous and could still be lethal.Pogue: Thanks for bringing that up. Poisonous and venomous don’t mean the same thing?Holford: No, no, no, not at all.Pogue: Poisonous versus venomous: it all comes down to the delivery system. If you bite it and get sick, it’s poisonous, but if it bites you and you get sick, it’s venomous. In general, the source of their toxins is different, as well.This poison dart frog becomes poisonous from its diet. If raised in captivity, on different foods, it can become non-toxic, whereas this rattlesnake generates its own venom. It’s built into its D.N.A. So, snakes, scorpions, spiders: which fearsome creature is the focus of Mandë’s work?Killer snails? Is it accurate to say that you study killer snails?Holford: Killer snails are actually my affectionate term for venomous marine snails. And so, these are snails that live in the sea, and they have a venom, like snakes or scorpions or spiders, and the venom can be very lethal to humans.Pogue: It’s true that the snail can kill you, but usually it’s just looking for dinner, a worm or a fish.So, I’m a fish. What happens to me?Holford: Well, what happens is this guy will smell that you’re in the water, right? He puts out something called a siphon, and it’s a chemosensory organ, smells that, “Hmm, tasty meal in the water,” then it sticks out something like a tongue. It’s called a “false” tongue, “proboscis.” And, on the tip of the tongue, it has a little tooth, filled with venom that then will get injected into the fish. The fish instantly will become paralyzed, depending on what cocktail of venom gets injected into it. The snail will then open its mouth really wide, swallow the fish whole and have a really nice, tasty meal.Pogue: The whole thing sounds so improbable.Holford: I love it. Just when you think you’ve heard of everything, nature will surprise you with something new.Pogue: So, what’s in that paralyzing venom? To find out, Mandë and her team collect specimens from around the world. Back at the lab, they analyze tissue samples from the snail’s muscular foot and its venom gland.Juliette Gorson: So, we’re eventually going to look at the D.N.A., so we can make a species identification. That, we can use the foot tissue for. And then the venom gland tissue we can use to look for the individual venom toxins within the venom duct.Pogue: Turns out, the cone snail’s venom isn’t one thing but a cocktail of as many as 250 short “mini” proteins, also called peptides.Holford: So, if you think of venom, think of it not as like a single bullet, right? It’s more like, I like to describe it as a cluster bomb. It’s a series of bullets coming at you, and each individual bullet has a target in the physiological system.Pogue: Each venom peptide has evolved to mount a very specific attack, often acting as keys that fit a cell’s lock-like receptors. In the case of the nervous system, that can prevent a specific neuron from transmitting an impulse or, conversely, jam the neuron open, generating a flood of signals.In the wild, all those targeted attacks paralyze the snail’s prey, but the precision with which the venom peptides act also means that they may have another role as medicines.Holford: And so, we study these venoms to try to figure out novel medicines for treating things in pain and cancer. Actually, they make great drugs because they’re highly specific, very fast-acting and very potent.Pogue: A venom curing instead of killing? Wouldn’t be the first time.There are currently at least seven drugs on the market developed out of the study of venoms. They include an anticoagulant derived from medicinal leeches and a diabetes medicine from Gila monsters. There’s even one already from cone snails, an analgesic to treat severe chronic pain.Holford: And it’s the exact peptide that you would find in the venom. It’s not a derivative of it, it’s not a small molecule, it’s exactly as nature expressed it in the animal.Gorson: And I’ll just run a simple D.N.A. extraction.Pogue: Mandë’s team has already made some major breakthroughs.Tanya Napolitano: So, I could do a nano-LC-MS and see what’s inside of here.Pogue: In 2014, they identified a peptide from another venomous snail that attacks liver tumor cells, inhibiting their growth. It’s cutting-edge work that’s reaping the rewards to be found at the intersection of chemistry and biology.Holford: Learning how the venom is used more in ecological settings helps to further us in terms of how we understand how it can be applied for medicinal or therapeutic applications. And so, right now, it’s a fun time to be a venom scientist, because those worlds are colliding.

How Killer Snail Venom Plays a Key Role in Drug Development Hero

What’s in this snail’s paralyzing venom?

Topic: Nature

Hero Feature