Samples of the asteroid Ryugu are the most pristine pieces of the solar system that scientists have in their possession.

A new analysis of Ryugu material confirms the porous rubble-pile asteroid is rich in carbon and finds it is extraordinarily primitive (SN: 3/16/20). It is also a member of a rare class of space rocks known as CI-type, researchers report online June 9 in Science.

Their analysis looked at material from the Japanese mission Hayabusa2, which collected 5.4 grams of dust and small rocks from multiple locations on the surface of Ryugu and brought that material to Earth in December 2020 (SN: 7/11/19; SN: 12/7/20). Using 95 milligrams of the asteroid’s debris, the researchers measured dozens of chemical elements in the sample and then compared abundances of several of those elements to those measured in rare meteorites classified as CI-type chondrites. Fewer than 10 meteorites found on Earth are CI chondrites.
This comparison confirmed Ryugu is a CI-type chondrite. But it also showed that unlike Ryugu, the meteorites appear to have been altered, or contaminated, by Earth’s atmosphere or even human handling over time. “The Ryugu sample is a much more fresh sample,” says Hisayoshi Yurimoto, a geochemist at Hokkaido University in Sapporo, Japan.

The researchers also measured the abundances of manganese-53 and chromium-53 in the asteroid and determined that melted water ice reacted with most of the minerals around 5 million years after the solar system’s start, altering those minerals, says Yurimoto. That water has since evaporated, but those altered minerals are still present in the samples. By studying them, the researchers can learn more about the asteroid’s history.

A few weeks ago, I was obsessed with my nose and throat. I was on a trip to Seattle to speak at a small, masks-required virology meeting about being a journalist during a pandemic. I went to graduate school there, so I was thrilled to see old friends and colleagues. But the irony that I was risking getting infected amid rising COVID-19 cases to get on a plane to talk with virologists about the pandemic didn’t escape me. I spent the whole week on high alert for the slightest hint of a sore throat or a runny nose. Despite masking, I worried that I’d get sick and be stuck thousands of miles from home or that I’d unknowingly pass the virus on to someone else.

Luckily, this story has a happy ending. I didn’t catch the coronavirus. None of my friends or former colleagues got sick. Although I didn’t escape completely unscathed; I did come down with a mystery, non-COVID cold that I suspect I caught from a friend’s baby. Still, the experience made me wonder ​​— what if I didn’t have to worry so much about becoming a disease spreader because there were COVID-19 vaccines that helped my body control the virus in my nose?
Researchers are working on vaccines that would hopefully do just that. You squirt these vaccines into your nostrils, rather than inject them into your arm muscle like the current COVID-19 shots. Sprayed up the nose, the vaccines teach our immune systems to fortify our nostrils against coronavirus, perhaps meaning we get less sick or making us less likely to transmit the virus to other people.

Jabs in the arm may not be as good at preventing transmission as nasal spray vaccines, some scientists suspect. The shots are better at building defenses that circulate in the blood or fluid that surrounds cells, which makes them great at protecting the lungs. And they have done what they are designed to do: curb severe disease and death (SN: 8/31/21). Booster doses help fend off severe COVID-19 better than the first two shots — especially for older people, studies show (SN: 4/29/22). But even with death rates down, that doesn’t mean our fight with coronavirus is over. Waning immune defenses combined with slippery versions of the coronavirus that can evade parts of our immune systems leave vaccinated people susceptible to infection. So we still need additional protection.

A panel of experts advising the U.S. Food and Drug Administration will meet later this month to weigh in on whether we might need a vaccine update for the fall. Updated shots may indeed be on the horizon: Preliminary data from vaccine developer Moderna show that its latest vaccine, which includes both omicron and the original virus, boosts the immune response against omicron as well as other variants such as delta, the company announced on June 8.

And on June 7 the FDA advisory committee recommended that the agency authorize a new COVID-19 vaccine for emergency use. This one, developed by the company Novavax, is based on a traditional method — showing the immune system purified viral proteins — which may be appealing to still unvaccinated people who are hesitant about the novel mRNA technology in Moderna’s and Pfizer’s shots (SN: 1/28/21). Other experts are working on vaccines that might hold up against an onslaught of variants, both present and future.
And then, there are the nasal spray vaccines. They could not only protect our lungs, but also the mucous membranes that line the upper regions of our respiratory tracts such as the nose. Such sprays would give us not only a motion detector ready to sense an intruder in an inner room of a building but also an alarm system that goes off the second the front door opens.

That type of alarm system isn’t a brand-new tool. For example, there is a nasal influenza vaccine available in the United States called FluMist, which teaches the body to recognize four different strains. And there is a similar one in Europe called Fluenz Tetra. Each flu virus included in these vaccines is weakened but can replicate in the body. The attenuated viruses grow best at cooler temperatures found in our noses, not the warm environment of our lungs, a barrier that keeps them from making it to the lungs and causing influenza. But by taking off in the nose, replicating viruses kick off an immune response, so our bodies learn to set up reinforcements there.

Already roughly a dozen potential COVID-19 nasal vaccines have made it to clinical trials around the world. One developed by a company called Altimmune was abandoned after early results showed the vaccine didn’t prompt a good immune response in healthy participants. Others have shown promise when tested in animals.

The prospect of having nasal vaccines that may be able to curb transmission better than existing shots is understandably exciting. But these types of vaccines still have a way to go before hitting local pharmacies or doctors’ offices.

First, it’s crucial for the nasal vaccines to strike the right balance. Their sprays must be strong enough to provoke our immune systems, but still weak enough that there aren’t unwelcome symptoms or side effects. It’s also of course important to ensure the safety of vaccine candidates that include live, weakened viruses.
Some nasal vaccine candidates are similar to the influenza vaccine and include live, weakened viruses. Most of these viruses aren’t the coronavirus itself, but rather harmless-to-human viruses that sport one coronavirus protein for our bodies to recognize. Others may not need a virus to grow in the body to work. One team is developing a nasal spray that includes only the coronavirus spike protein, which helps the virus break into cells. That spike spray could serve as a boost for people who received one of the mRNA vaccines, coaxing important immune cells to come live in the nose and other parts of the respiratory tract. Once there, those immune cells would be poised to kick into high gear if the coronavirus invades.

Second, nasal sprays face the same problem as current COVID-19 vaccines. What happens when the virus evolves in ways that help it hide from our immune system? We’ve already seen the consequences of that thanks to the delta and omicron waves that raced around the globe. And from 2016 to 2018, FluMist stumbled in the face of tweaked versions of some influenza viruses. Experts recommended that people get a different type of flu shot in those seasons. Just as researchers are considering updating existing COVID-19 shots to better mimic the viral variants currently wreaking havoc, nasal vaccines may also need regular updating.

If I had a choice, I would never catch coronavirus. But in the grand scheme of things, it’d be nice if a spray up my nose could drastically lower my chances of passing it on to someone else if I did get infected. If they make it to consumers, the nasal vaccines could make future COVID-19 waves much smaller than they are now. And after more than two years of navigating ever-larger waves, wouldn’t that be nice?

In my opinion, the most satisfying science documentary TV series ever made was a 1970s British production called Connections. Hosted by impish historian James Burke, wearing bell-bottoms and thick-framed tortoiseshell glasses, each episode revealed how one small innovation from earlier human civilizations led to another and then another and another, culminating in the invention of some ultramodern (for the 1970s) technology.

Watching these pieces of the past come together was deeply gratifying, if not a little dizzying. The present is so familiar that it feels inevitable. But it was striking to see modern civilization, even modern humans, in context, to recognize how all that we are now actually hinges on countless moments of invention, improvement and experimentation in the deep past.

I had a similar reaction to The Rise and Reign of the Mammals, paleontologist Steve Brusatte’s sweeping history of the animals that have, for the moment, inherited the Earth. Moving generally forward in time, the book describes how the mammalian line progressively acquired a range of features that have come to define what a mammal is.

Some of the moments of evolutionary invention that led to what we now think of as a mammal are remarkably subtle. There’s the hard roof of the mouth that created a dedicated airway to the lungs, allowing mammal ancestors to eat and breathe at the same time. There’s the change from a spine that bends from left to right (which produces the classically reptilian side-to-side gait) to one that enables bending up and down, which ultimately allowed mammals to take in more oxygen as they moved, helping them run faster. And there’s the variety of tooth shapes — incisors, canines, premolars and molars — that made it possible for mammals to eat many kinds of food. A reptile, by contrast, tends to have just one tooth type.

Some mammalian characteristics are very familiar: milk production, warm-bloodedness, hair. But there’s one less–well-known evolutionary advance that was in its humble way quite profound, setting “us apart from amphibians, reptiles, and birds,” Brusatte writes. It’s a joint in the jaw that makes chewing possible (SN: 8/17/19, p. 8). The ability to chew was “a major evolutionary turning point,” he writes. “It triggered a domino chain of changes to mammalian feeding, intelligence, and reproduction.”
Brusatte also describes a second small, curious adaptation: the transformation of two bones in the reptile jaw, which migrated to the inner ear to become two members of a famous trio, the hammer and anvil (the third is the stirrup). These inner ear bones are the basis for yet another key mammalian feature: the ability to hear a wide range of frequencies, particularly in the upper register (SN Online: 12/6/19).

The story of the Age of Mammals is often told as the flip side to the dinosaurs’ demise. But the fossil record reveals that mammals were hardly newcomers: They arose around the same time as the dinosaurs, over 200 million years ago. Even during the Age of Dinosaurs, “in the smaller and hidden niches, it was already the Age of Mammals,” Brusatte writes. “Mammals were better than the dinosaurs at being small.”

Within just a few hundred thousand years of the asteroid impact that wiped out all nonbird dinos some 66 million years ago, mammals moved in to fill the vacancy, rapidly getting a lot bigger, ballooning from, say, mouse-sized to beaver-sized (SN: 12/7/19, p. 32). Pretty soon, they got a lot smarter too. In a geologic blink — a scant 10 million years — mammals’ brains caught up with their brawn, and then the Age of Mammals was off to the races (SN: 5/7/22 & 5/21/22, p. 18).

Paleontology narratives often require refocusing a story’s lens in a way that can be jarring, zooming out to encompass Earth-wide climate cataclysms and mass extinctions and then in again to describe tiny bones and obscure species. Brusatte, though, is a nimble storyteller and he’s chosen an engrossing story to tell.

As a science writer, I often find myself focusing on minute advances, studying tiny threads. So it’s satisfying to sit back and admire the full tapestry as presented in The Rise and Reign of the Mammals. Reading this book reminded me what I most enjoy about geology, paleontology and the evolution of life on Earth: This planet has got some epic stories.

Buy The Rise and Reign of the Mammals from Bookshop.org. Science News is a Bookshop.org affiliate and will earn a commission on purchases made from links in this article.