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A scientific mission to save the sharks

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A scientific mission to save the sharks

A hammerhead shark less than one meter long swims frantically in a plastic container aboard a boat in the Sanquianga National Natural Park, off Colombia’s Pacific coast. It is a delicate female Sphyrna corona, the world’s smallest hammerhead species, and goes by the local name cornuda amarilla—yellow hammerhead—because of the color of its fins and the edges of its splendid curved head, which is full of sensors to perceive the movement of its prey.

Marine biologist Diego Cardeñosa of Florida International University, along with local fishermen, has just captured the shark and implanted it with an acoustic marker before quickly returning it to the murky waters. A series of receivers will help to track its movements for a year, to map the coordinates of its habitat—valuable information for its protection.

That hammerhead is far from the only shark species that keeps the Colombian biologist busy. Cardeñosa’s mission is to build scientific knowledge to support shark conservation, either by locating the areas where the creatures live or by identifying, with genetic tests, the species that are traded in the world’s main shark markets.

Sharks are under threat for several reasons. The demand for their fins to supply the mainly Asian market (see box) is a very lucrative business: Between 2012 and 2019, it generated $1.5 billion. This, plus their inclusion in bycatch—fish caught unintentionally in the fishing industry—as well as the growing market for shark meat, leads to the death of millions every year. In 2019 alone the estimated total killed was at least 80 million sharks, 25 million of which were endangered species. In fact, in the Hong Kong market alone, a major trading spot for shark fins, two-thirds of the shark species sold there are at risk of extinction, according to a 2022 study led by Cardeñosa and molecular ecologist Demian Chapman, director of the shark and ray conservation program at Mote Marine Laboratory in Sarasota, Florida.

Sharks continue to face a complicated future despite decades of legislation designed to protect them. In 2000, the US Congress passed the Shark Finning Prohibition Act, and in 2011 the Shark Conservation Act. These laws require that sharks brought ashore by fishermen have all their fins naturally attached and aim to end the practice of stripping the creatures of their fins and returning them, mutilated, to the water to die on the seafloor. Ninety-four other countries have implemented similar regulations.

Perhaps the main political and diplomatic tool for shark conservation is in the hands of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), composed of 183 member countries plus the European Union. The treaty offers three degrees of protection, or appendices, to more than 40,000 species of animals and plants, imposing prohibitions and restrictions on their trade according to their threat status.

Sharks were included in CITES Appendix II—which includes species that are not endangered but could become so if trade is not controlled—in February 2003, with the addition of two species: the basking shark (Cetorhinus maximus) and the whale shark (Rhincodon typus). Following that, the list of protected species grew to 12 and then increased significantly in November 2023 with the inclusion of 60 more species of sharks in CITES Appendix II.

But do these tools actually protect sharks? To seek out answers, over the past decade researchers have worked to develop tests that can easily identify which species of sharks are being traded—and determine whether protected species continue to be exploited. They have also focused on studying shark populations around the world in order to provide information for the establishment of protected areas that can help safeguard these animals.

A scientific mission to save the sharks Read More »

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How do brainless creatures control their appetites?

apetite, Behavioral science, Biology, hunger, hydras, neurobiology, Science / /

Feed me! —

Separate systems register when the animals have eaten and control feeding behaviors.

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Image of a greenish creature with a long stalk and tentacles, against a black background.

The hydra is a Lovecraftian-looking microorganism with a mouth surrounded by tentacles on one end, an elongated body, and a foot on the other end. It has no brain or centralized nervous system. Despite the lack of either of those things, it can still feel hunger and fullness. How can these creatures know when they are hungry and realize when they have had enough?

While they lack brains, hydra do have a nervous system. Researchers from Kiel University in Germany found they have an endodermal (in the digestive tract) and ectodermal (in the outermost layer of the animal) neuronal population, both of which help them react to food stimuli. Ectodermal neurons control physiological functions such as moving toward food, while endodermal neurons are associated with feeding behavior such as opening the mouth—which also vomits out anything indigestible.

Even such a limited nervous system is capable of some surprisingly complex functions. Hydras might even give us some insights into how appetite evolved and what the early evolutionary stages of a central nervous system were like.

No, thanks, I’m full

Before finding out how the hydra’s nervous system controls hunger, the researchers focused on what causes the strongest feeling of satiety, or fullness, in the animals. They were fed with the brine shrimp Artemia salina, which is among their usual prey, and exposed to the antioxidant glutathione. Previous studies have suggested that glutathione triggers feeding behavior in hydras, causing them to curl their tentacles toward their mouths as if they are swallowing prey.

Hydra fed with as much Artemia as they could eat were given glutathione afterward, while the other group was only given only glutathione and no actual food. Hunger was gauged by how fast and how often they opened their mouths.

It turned out that the first group, which had already glutted themselves on shrimp, showed hardly any response to glutathione eight hours after being fed. Their mouths barely opened—and slowly if so—because they were not hungry enough for even a feeding trigger like glutathione to make them feel they needed seconds.

It was only at 14 hours post-feeding that the hydra that had eaten shrimp opened their mouths wide enough and fast enough to indicate hunger. However, those that were not fed and only exposed to glutathione started showing signs of hunger only four hours after exposure. Mouth opening was not the only behavior provoked by hunger since starved animals also somersaulted through the water and moved toward light, behaviors associated with searching for food. Sated animals would stop somersaulting and cling to the wall of the tank they were in until they were hungry again.

Food on the “brain”

After observing the behavioral changes in the hydra, the research team looked into the neuronal activity behind those behaviors. They focused on two neuronal populations, the ectodermal population known as N3 and the endodermal population known as N4, both known to be involved in hunger and satiety. While these had been known to influence hydra feeding responses, how exactly they were involved was unknown until now.

Hydra have N3 neurons all over their bodies, especially in the foot. Signals from these neurons tell the animal that it has eaten enough and is experiencing satiety. The frequency of these signals decreased as the animals grew hungrier and displayed more behaviors associated with hunger. The frequency of N3 signals did not change in animals that were only exposed to glutathione and not fed, and these hydra behaved just like animals that had gone without food for an extended period of time. It was only when they were given actual food that the N3 signal frequency increased.

“The ectodermal neuronal population N3 is not only responding to satiety by increasing neuronal activity, but is also controlling behaviors that changed due to feeding,” the researchers said in their study, which was recently published in Cell Reports.

Though N4 neurons were only seen to communicate indirectly with the N3 population in the presence of food, they were found to influence eating behavior by regulating how wide the hydras opened their mouths and how long they kept them open. Lower frequency of N4 signals was seen in hydra that were starved or only exposed to glutathione. Higher frequency of N4 signals were associated with the animals keeping their mouths shut.

So, what can the neuronal activity of a tiny, brainless creature possibly tell us about the evolution of our own complex brains?

The researchers think the hydra’s simple nervous system may parallel the much more complex central and enteric (in the gut) nervous systems that we have. While N3 and N4 operate independently, there is still some interaction between them. The team also suggests that the way N4 regulates the hydra’s eating behavior is similar to the way the digestive tracts of mammals are regulated.

“A similar architecture of neuronal circuits controlling appetite/satiety can be also found in mice where enteric neurons, together with the central nervous system, control mouth opening,” they said in the same study.

Maybe, in a way, we really do think with our gut.

Cell Reports, 2024. DOI: 10.1016/j.celrep.2024.114210

How do brainless creatures control their appetites? Read More »

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Blue Origin joins SpaceX and ULA in new round of military launch contracts

blue origin, falcon heavy, launch, military space, new glenn, Science, Space, spacex, united launch alliance, vulcan / /

Playing with the big boys —

“Lane 1 serves our commercial-like missions that can accept more risk.”

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Blue Origin's New Glenn rocket on the launch pad for testing earlier this year.

Enlarge / Blue Origin’s New Glenn rocket on the launch pad for testing earlier this year.

After years of lobbying, protests, and bidding, Jeff Bezos’s space company is now a military launch contractor.

The US Space Force announced Thursday that Blue Origin will compete with United Launch Alliance and SpaceX for at least 30 military launch contracts over the next five years. These launch contracts have a combined value of up to $5.6 billion.

This is the first of two major contract decisions the Space Force will make this year as the military seeks to foster more competition among its roster of launch providers and reduce its reliance on just one or two companies.

For more than a decade following its formation from the merger of Boeing and Lockheed Martin rocket programs, ULA was the sole company certified to launch the military’s most critical satellites. This changed in 2018, when SpaceX started launching national security satellites for the military. In 2020, despite protests from Blue Origin seeking eligibility, the Pentagon selected ULA and SpaceX to continue sharing launch duties.

The National Security Space Launch (NSSL) program is in charge of selecting contractors to deliver military surveillance, navigation, and communications satellites into orbit.

Over the next five years, the Space Force wants to tap into new launch capabilities from emerging space companies. The procurement approach for this new round of contracts, known as NSSL Phase 3, is different from the way the military previously bought launch services. Instead of grouping all national security launches into one monolithic contract, the Space Force is dividing them into two classifications: Lane 1 and Lane 2.

The Space Force’s contract announced Thursday was for Lane 1, which is for less demanding missions to low-Earth orbit. These missions include smaller tech demos, experiments, and launches for the military’s new constellation of missile-tracking and data-relay satellites, an effort that will eventually include hundreds or thousands of spacecraft managed by the Pentagon’s Space Development Agency.

This fall, the Space Force will award up to three contracts for Lane 2, which covers the government’s most sensitive national security satellites, which require “complex security and integration requirements.” These are often large, heavy spacecraft weighing many tons and sometimes needing to go to orbits thousands of miles from Earth. The Space Force will require Lane 2 contractors to go through a more extensive certification process than is required in Lane 1.

“Today marks the beginning of this innovative, dual-lane approach to launch service acquisition, whereby Lane 1 serves our commercial-like missions that can accept more risk and Lane 2 provides our traditional, full mission assurance for the most stressing heavy-lift launches of our most risk-averse missions,” said Frank Calvelli, assistant secretary of the Air Force for space acquisition and integration.

Meeting the criteria

The Space Force received seven bids for Lane 1, but only three companies met the criteria to join the military’s roster of launch providers. The basic requirement to win a Lane 1 contract was for a company to show its rocket can place at least 15,000 pounds of payload mass into low-Earth orbit, either on a single flight or over a series of flights within a 90-day period.

The bidders also had to substantiate their plan to launch the rocket they proposed to use for Lane 1 missions by December 15 of this year. A spokesperson for Space Systems Command said SpaceX proposed using their Falcon 9 and Falcon Heavy rockets, and ULA offered its Vulcan rocket. Those launchers are already flying. Blue Origin proposed its heavy-lift New Glenn rocket, slated for an inaugural test flight no earlier than September.

“As we anticipated, the pool of awardees is small this year because many companies are still maturing their launch capabilities,” said Brig. Gen. Kristin Panzenhagen, program executive officer for the Space Force’s assured access to space division. “Our strategy accounted for this by allowing on-ramp opportunities every year, and we expect increasing competition and diversity as new providers and systems complete development.”

A SpaceX Falcon Heavy rocket lifts off from NASA's Kennedy Space Center in Florida.

Enlarge / A SpaceX Falcon Heavy rocket lifts off from NASA’s Kennedy Space Center in Florida.

Trevor Mahlmann/Ars Technica

The Space Force plans to open up the first on-ramp opportunity for Lane 1 as soon as the end of this year. Companies with medium-lift rockets in earlier stages of development, such as Rocket Lab, Relativity Space, Firefly Aerospace, and Stoke Space, will have the chance to join ULA, SpaceX, and Blue Origin in the Lane 1 pool at that time. The structure of the NSSL Phase 3 contracts allow the Pentagon to take advantage of emerging launch capabilities as soon as they become available, according to Calvelli.

In a statement, Panzenhagen said having additional launch providers will increase the Space Force’s “resiliency” in a time of increasing competition between the US, Russia, and China in orbit. “Launching more risk-tolerant satellites on potentially less mature launch systems using tailored independent government mission assurance could yield substantial operational responsiveness, innovation, and savings,” Panzenhagen said.

More competition, theoretically, will also deliver lower launch prices to the Space Force. SpaceX and Blue Origin rockets are partially reusable, while ULA eventually plans to recover and reuse Vulcan main engines.

Over the next five years, Space Systems Command will dole out fixed-price “task orders” to ULA, SpaceX, and Blue Origin for groups of Lane 1 missions. The first batch of missions up for awards in Lane 1 include seven launches for the Space Development Agency’s missile tracking mega-constellation, plus a task order for the National Reconnaissance Office, the government’s spy satellite agency. However, military officials require a rocket to have completed at least one successful orbital launch to win a Lane 1 task order, and Blue Origin’s New Glenn doesn’t yet satisfy this requirement.

The Space Force will pay Blue Origin $5 million for an “initial capabilities assessment” for Lane 1. SpaceX and ULA, the military’s incumbent launch contractors, will each receive $1.5 million for similar assessments.

ULA, SpaceX, and Blue Origin are also the top contenders to win Lane 2 contracts later this year. In order to compete in Lane 2, a launch provider must show it has a plan for its rockets to meet the Space Force’s stringent certification requirements by October 1, 2026. SpaceX’s Falcon 9 and Falcon Heavy are already certified, and ULA’s Vulcan is on a path to achieve this milestone by the end of this year, pending a successful second test flight in the next few months. A successful debut of New Glenn by the end of this year would put the October 2026 deadline within reach of Blue Origin.

Blue Origin joins SpaceX and ULA in new round of military launch contracts Read More »

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Rocket Report: Starship is on the clock; Virgin Galactic at a crossroads

Science, Space / /

Fire at Moses Lake —

The payloads for the first Ariane 6 launch are buttoned up for flight next month.

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The payload fairing for the first test flight of Europe's Ariane 6 rocket has been positioned around the small batch of satellites that will ride it into orbit.

Enlarge / The payload fairing for the first test flight of Europe’s Ariane 6 rocket has been positioned around the small batch of satellites that will ride it into orbit.

Welcome to Edition 6.48 of the Rocket Report! Fresh off last week’s dramatic test flight of SpaceX’s Starship, teams in Texas are wasting no time gearing up for the next launch. Ground crews are replacing the entire heat shield on the next Starship spacecraft to overcome deficiencies identified on last week’s flight. SpaceX has a whole lot to accomplish with Starship in the next several months if NASA is going to land astronauts on the Moon by the end of 2026.

As always, we welcome reader submissions, and if you don’t want to miss an issue, please subscribe using the box below (the form will not appear on AMP-enabled versions of the site). Each report will include information on small-, medium-, and heavy-lift rockets as well as a quick look ahead at the next three launches on the calendar.

Virgin Galactic won’t be flying again any time soon. After an impressive but brief flurry of spaceflight activity—seven human spaceflights in a year, even to suborbital space, is unprecedented for a private company—Virgin Galactic will now be grounded again for at least two years, Ars reports. That’s because Colglazier and Virgin Galactic are betting it all on the development of a future “Delta class” of spaceships modeled on VSS Unity, which made its last flight to suborbital space Saturday. Virgin Galactic, founded by Richard Branson, now finds itself at a crossroads as it chases profitability, which VSS Unity had no hope of helping it achieve despite two decades of development and billions of dollars spent.

An uncertain future … Now, Virgin Galactic’s already anemic revenue numbers will drop to near zero as the company spends more capital to bring two Delta-class spaceships online. The goal is to start flying them in 2026. These vehicles are designed to be more easily reusable and carry six instead of four passengers. This timeline seems highly ambitious given that, at this point, the company is only developing tooling for the vehicles and won’t begin major parts fabrication until later this year. Virgin Galactic is betting on the Delta-class ships as its stock price has precipitously fallen over the last couple of years. In fact, Virgin Galactic announced a reverse stock split this week in a bid to maintain its listing on the New York Stock Exchange. (submitted by Ken the Bin)

Unpacking North Korea’s advancements in rocketry. Late last month, North Korea signaled it has made—or more accurately, is still trying to make—a pretty big leap in rocket technology. The isolated totalitarian state’s official news agency said it tested a new type of satellite launcher on May 27 powered by petroleum fuel and cryogenic liquid oxygen propellant. This is a radical change in North Korea’s rocket program, and it took astute outside observers by surprise. Previous North Korean rockets used hypergolic propellants, typically hydrazine and nitrogen tetroxide, or solid fuels, which are also well-suited for military ballistic missiles. Kerosene and liquid oxygen, on the other hand, aren’t great propellants for missiles but are good for a pure space launcher.

Who’s helping?… The May 27 launch failed shortly after liftoff, while the unnamed rocket was still in first stage flight over the Yellow Sea. But there is tangible and circumstantial evidence that Russia played a role in the launch. The details are still murky, but North Korean leader Kim Jong Un visited a Russian spaceport last September and met with Russian President Vladimir Putin, who suggested Russian help for the North’s satellite launch program was on the agenda at the summit. South Korean defense officials said Russian experts visited North Korea in the run-up to the May 27 launch. If Russia exported a kerosene-fueled rocket engine, or perhaps an entire booster, to North Korea, it wouldn’t be the first time Russia has shipped launch technology to the Korean Peninsula. Russia provided South Korea’s nascent space launch program with three fully outfitted rocket boosters for test flights in 2009, 2010, and 2023 before the South developed a fully domestic rocket on its own.

The easiest way to keep up with Eric Berger’s space reporting is to sign up for his newsletter, we’ll collect his stories in your inbox.

ABL signs deal with a new launch customer. ABL Space Systems, which is still trying to get its light launcher into orbit, has a new customer. Scout Space announced this week it has signed a launch agreement with ABL for the launch of a small spacecraft called “Owlet-01” on the third flight of ABL’s RS1 rocket, Space News reports. Scout Space, which describes itself as focused on space security and comprehensive space domain awareness, develops optical sensors to monitor the space environment. Owlet-01 will fly a telescope designed to detect other objects in space, a capability highly sought by the US military.

Still waiting on Flight 2 … The launch agreement between ABL and Space Scout is contingent on the outcome of the second flight of the RS1 rocket, which ABL has been preparing for the last few months. ABL hasn’t provided any public updates on the status of the second RS1 test flight since announcing in March that pre-flight preparations were underway at Kodiak Island, Alaska. The first RS1 rocket fell back on its launch pad in Alaska a few seconds after lifting off in January 2023. The RS1 is capable of hauling a payload of more than 1.3 metric tons to low-Earth orbit. (submitted by Ken the Bin)

Rocket Report: Starship is on the clock; Virgin Galactic at a crossroads Read More »

shackleton-died-on-board-the-quest;-ship’s-wreckage-has-just-been-found

Shackleton died on board the Quest; ship’s wreckage has just been found

Archaeology, history, maritime archaeology, Science, shipwrecks, Sir Ernest Shackleton / /

A ship called Quest —

“His final voyage kind of ended that Heroic Age of Exploration.”

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Ghostly historical black and white photo of a ship breaking in two in the process of sinking

Enlarge / Ernest Shackleton died on board the Quest in 1922. Forty years later, the ship sank off Canada’s Atlantic Coast.

Tore Topp/Royal Canadian Geographical Society

Famed polar explorer Ernest Shackleton famously defied the odds to survive the sinking of his ship, Endurance, which became trapped in sea ice in 1914. His luck ran out on his follow-up expedition; he died unexpectedly of a heart attack in 1922 on board a ship called Quest. The ship survived that expedition and sailed for another 40 years, eventually sinking in 1962 after its hull was pierced by ice on a seal-hunting run. Shipwreck hunters have now located the remains of the converted Norwegian sealer in the Labrador Sea, off the coast of Newfoundland, Canada. The wreckage of Endurance was found in pristine condition in 2022 at the bottom of the Weddell Sea.

The Quest expedition’s relatively minor accomplishments might lack the nail-biting drama of the Endurance saga, but the wreck is nonetheless historically significant. “His final voyage kind of ended that Heroic Age of Exploration, of polar exploration, certainly in the south,” renowned shipwreck hunter David Mearns told the BBC. “Afterwards, it was what you would call the scientific age. In the pantheon of polar ships, Quest is definitely an icon.”

As previously reported, Endurance set sail from Plymouth, Massachusetts, on August 6, 1914, with Shackleton joining his crew in Buenos Aires, Argentina. By January 1915, the ship had become hopelessly locked in sea ice, unable to continue its voyage. For 10 months, the crew endured the freezing conditions, waiting for the ice to break up. The ship’s structure remained intact, but by October 25, Shackleton realized Endurance was doomed. He and his men opted to camp out on the ice some two miles (3.2 km) away, taking as many supplies as they could with them.

Compacted ice and snow continued to fill the ship until a pressure wave hit on November 13, crushing the bow and splitting the main mast—all of which was captured on camera by crew photographer Frank Hurley. Another pressure wave hit in late afternoon November 21, lifting the ship’s stern. The ice floes parted just long enough for Endurance to finally sink into the ocean, before closing again to erase any trace of the wreckage.

When the sea ice finally disintegrated in April 1916, the crew launched lifeboats and managed to reach Elephant Island five days later. Shackleton and five of his men set off for South Georgia the next month to get help—a treacherous 720-mile journey by open boat. A storm blew them off course, and they ended up landing on the unoccupied southern shore. So Shackleton left three men behind while he and a companion navigated dangerous mountain terrain to reach the whaling station at Stromness on May 2. A relief ship collected the other three men and finally arrived back on Elephant Island in August. Miraculously, Shackleton’s entire crew was still alive.

Endurance, which sank off the coast of Antarctica in 1915 after being crushed by pack ice. An expedition located the shipwreck in pristine condition in 2022 after nearly 107 years. ” height=”424″ src=”https://cdn.arstechnica.net/wp-content/uploads/2022/03/endurance2CROP-640×424.jpg” width=”640″>

Enlarge / This is the stern of the good ship Endurance, which sank off the coast of Antarctica in 1915 after being crushed by pack ice. An expedition located the shipwreck in pristine condition in 2022 after nearly 107 years.

Falklands Maritime Heritage Trust/NatGeo

Shackleton’s last voyage

By the time Shackleton got back to England, the country was embroiled in World War I, and many of his men enlisted. Shackleton was considered too old for active service. He was also deeply in debt from the Endurance expedition, earning a living on the lecture circuit. But he still dreamed of making another expedition to the Arctic Ocean north of Alaska to explore the Beaufort Sea. He got seed money (and eventually full funding) from an old school chum, John Quillier Rowett. Shackleton purchased a wooden Norwegian whaler, Foca I, which his wife Emily renamed Quest.

Shackleton died on board the Quest; ship’s wreckage has just been found Read More »

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IV infusion enables editing of the cystic fibrosis gene in lung stem cells

Biology, CRISPR, Cystic Fibrosis, gene editing, gene therapy, Genetics, medicine, Science / /

Right gene in the right place —

Approach relies on lipid capsules like those in the mRNA vaccines.

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Abstract drawing of a pair of human hands using scissors to cut a DNA strand, with a number of human organs in the background.

The development of gene editing tools, which enable the specific targeting and correction of mutations, hold the promise of allowing us to correct those mutations that cause genetic diseases. However, the technology has been around for a while now—two researchers were critical to its development in 2020—and there have been only a few cases where gene editing has been used to target diseases.

One of the reasons for that is the challenge of targeting specific cells in a living organism. Many genetic diseases affect only a specific cell type, such as red blood cells in sickle-cell anemia, or specific tissue. Ideally, to limit potential side effects, we’d like to ensure that enough of the editing takes place in the affected tissue to have an impact, while minimizing editing elsewhere to limit side effects. But our ability to do so has been limited. Plus, a lot of the cells affected by genetic diseases are mature and have stopped dividing. So, we either need to repeat the gene editing treatments indefinitely or find a way to target the stem cell population that produces the mature cells.

On Thursday, a US-based research team said that they’ve done gene editing experiments that targeted a high-profile genetic disease: cystic fibrosis. Their technique largely targets the tissue most affected by the disease (the lung), and occurs in the stem cell populations that produce mature lung cells, ensuring that the effect is stable.

Getting specific

The foundation of the new work is the technology that gets the mRNAs of the COVID-19 mRNA vaccines inside cells. The nucleic acids of an mRNA are large molecules with a lot of charged pieces, which makes it difficult for them to cross a membrane to get inside of a cell. To overcome that problem, the researchers package the mRNA inside a bubble of lipids, which can then fuse with cell membranes, dumping the mRNA inside the cell.

This process, as the researchers note, has two very large advantages: We know it works, and we know it’s safe. “More than a billion doses of lipid nanoparticle–mRNA COVID-19 vaccines have been administered intramuscularly worldwide,” they write, “demonstrating high safety and efficacy sustained through repeatable dosing.” (As an aside, it’s interesting to contrast the research community’s view of the mRNA vaccines to the conspiracies that circulate widely among the public.)

There’s one big factor that doesn’t matter for vaccine delivery but does matter for gene editing: They’re not especially fussy about what cells they target for delivery. So, if you want to target something like blood stem cells, then you need to alter the lipid particles in some way to get them to preferentially target the cells of your choice.

There are a lot of ideas on how to do this, but the team behind this new work found a relatively simple one: changing the amount of positively charged lipids on the particle. In 2020, they published a paper in which they describe the development of selective organ targeting (SORT) lipid nanoparticles. By default, many of the lipid particles end up in the liver. But, as the fraction of positively charged lipids increases, the targeting shifts to the spleen and then to the lung.

So, presumably, because they know they can target the lung, they decided to use SORT particles to send a gene editing system specific to cystic fibrosis, which primarily affects that tissue and is caused by mutations in a single gene. While it’s relatively easy to get things into the lung, it’s tough to get them to lung cells, given all the mucus, cilia, and immune cells that are meant to take care of foreign items in the lung.

IV infusion enables editing of the cystic fibrosis gene in lung stem cells Read More »

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Huge telehealth fraud indictment may wreak havoc for Adderall users, CDC warns

adderall, ADHD, CDC, department of justice, Done Global, fentanyl, fraud, health, illicit drugs, overdose, prescription drug, Science, stimulants, telehealth / /

Tragic —

The consequences are dangerous, possibly even deadly, for patients across the US.

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Ten milligram tablets of the hyperactivity drug, Adderall, made by Shire Plc, is shown in a Cambridge, Massachusetts pharmacy Thursday, January 19, 2006.

Enlarge / Ten milligram tablets of the hyperactivity drug, Adderall, made by Shire Plc, is shown in a Cambridge, Massachusetts pharmacy Thursday, January 19, 2006.

The Centers for Disease Control and Prevention on Thursday warned that a federal indictment of an allegedly fraudulent telehealth company may lead to a massive, nationwide disruption in access to ADHD medications—namely Adderall, but also other stimulants—and could possibly increase the risk of injuries and overdoses.

“A disruption involving this large telehealth company could impact as many as 30,000 to 50,000 patients ages 18 years and older across all 50 US states,” the CDC wrote in its health alert.

The CDC warning came on the heels of an announcement from the Justice Department Thursday that federal agents had arrested two people in connection with an alleged scheme to illegally distribute Adderall and other stimulants through a subscription-based online telehealth company called Done Global.  The company’s CEO and founder, Ruthia He, was arrested in Los Angeles, and its clinical president, David Brody, was arrested in San Rafael, California.

“As alleged, these defendants exploited the COVID-19 pandemic to develop and carry out a $100 million scheme to defraud taxpayers and provide easy access to Adderall and other stimulants for no legitimate medical purpose,” Attorney General Merrick Garland said in a statement. “Those seeking to profit from addiction by illegally distributing controlled substances over the Internet should know that they cannot hide their crimes and that the Justice Department will hold them accountable.”

Deadly consequences

According to the Justice Department, Done Global generated $100 million in revenue by arranging for the prescription of over 40 million pills of Adderall and other stimulants, which are addictive medications used to treat ADHD (attention-deficit/hyperactivity disorder). Done Global allegedly eased access to the drugs by limiting the information available to prescribers, instructing prescribers to prescribe Adderall and other stimulants even if the patient didn’t qualify, and mandating that the prescribing appointments last no longer than 30 minutes. The company also discouraged prescriber follow-up appointments and added an “auto-refill” feature.

Prosecutors further allege that He and Brody continued with their scheme after becoming aware that patients had overdosed and died.

The CDC cautioned that the disruption from lost access to Done Global prescriptions comes amid a long-standing, nationwide shortage of Adderall and other stimulant medications. For patients with ADHD, the disruption could be harmful. “Untreated ADHD is associated with adverse outcomes, including social and emotional impairment, increased risk of drug or alcohol use disorder, unintentional injuries, such as motor vehicle crashes, and suicide,” the CDC warns. Further, a loss of access could drive some to seek illicit sources of the drugs, which could turn deadly.

“Patients whose care or access to prescription stimulant medications is disrupted, and who seek medication outside of the regulated healthcare system, might significantly increase their risk of overdose due to the prevalence of counterfeit pills in the illegal drug market that could contain unexpected substances, including fentanyl,” the CDC said. Fentanyl is a synthetic opioid that is up to 50 times stronger than heroin and 100 times stronger than morphine.

The Drug Enforcement Administration recently reported that seven out of every 10 pills seized from the illegal drug market contain a potentially lethal dose of illegally made fentanyl, the CDC noted.

This post was updated to clarify that the DEA’s data indicated that 70 percent of illicit pills seized contained “potentially” lethal doses, which was not included in the CDC’s warning.

Huge telehealth fraud indictment may wreak havoc for Adderall users, CDC warns Read More »

to-kill-the-competition,-bacteria-throw-pieces-of-dead-viruses-at-them

To kill the competition, bacteria throw pieces of dead viruses at them

bacteria, Biology, evolution, phages, Science / /

Murderous —

A network of mutual murder ensures that diverse populations of bacteria survive.

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A green, lawn like background with an orange item consisting of legs, a narrow shaft, and a polygonal head.

Enlarge / This is an intact phage. A tailocin looks like one of these with its head cut off.

Long before humans became interested in killing bacteria, viruses were on the job. Viruses that attack bacteria, termed “phages” (short for bacteriophage), were first identified by their ability to create bare patches on the surface of culture plates that were otherwise covered by a lawn of bacteria. After playing critical roles in the early development of molecular biology, a number of phages have been developed as potential therapies to be used when antibiotic resistance limits the effectiveness of traditional medicines.

But we’re relative latecomers in terms of turning phages into tools. Researchers have described a number of cases where bacteria have maintained pieces of disabled viruses in their genomes and converted them into weapons that can be used to kill other bacteria that might otherwise compete for resources. I only just became aware of that weaponization, thanks to a new study showing that this process has helped maintain diverse bacterial populations for centuries.

Evolving a killer

The new work started when researchers were studying the population of bacteria associated with a plant growing wild in Germany. The population included diverse members of the genus Pseudomonas, which can include plant pathogens. Normally, when bacteria infect a new victim, a single strain expands dramatically as it successfully exploits its host. In this case, though, the Pseudomonas population contained a variety of different strains that appeared to maintain a stable competition.

To learn more, the researchers obtained over 1,500 individual genomes from the bacterial population. Over 99 percent of those genomes contained pieces of virus, with the average bacterial strain having two separate chunks of virus lurking in their genomes. All of these had missing parts compared to a functional virus, suggesting they were the product of a virus that had inserted in the past but had since picked up damage that disabled them.

On its own, that’s not shocking. Lots of genomes (including our own) have plenty of disabled viruses in them. But bacteria tend to eliminate extraneous DNA from their genomes fairly quickly. In this case, one particular viral sequence appeared to date back to the common ancestor of many of the strains since all of them had the virus inserted at the same location of the genome, and all instances of this particular virus had been disabled by losing the same set of genes. The researchers termed this sequence VC2.

Many phages have a stereotypical structure: a large “head” that contains their genetic material, perched on top of a stalk that ends in a set of “legs” that help latch on to their bacterial victims. Once the legs make contact, a stalk contracts, an action that helps transfer the virus’ genome into the bacterial cell. In VC2’s case, all copies of it lacked the genes for producing the head section, as well as all the genes needed for processing its genome during infection.

This made the researchers suspect VC2 was something called a “tailocin.” These are former phages that have been domesticated by bacteria so they can be used to harm the bacteria’s potential competition. Bacteria with a tailocin can produce partial phages that consist only of the legs and stalk. These tailocins can still find and latch on to other bacteria, but when the stalk contracts, there’s no genome to inject. Instead, this just opens a hole in the membrane of their victim, partially eliminating the boundary of the cell and allowing some of its contents to leak out, leading to its death.

An evolutionary free-for-all

To confirm that the VC2 sequence encodes a tailocin, the researchers grew some bacteria that contained the sequence, purified proteins from it, and used electron microscopy to confirm that they contained headless phages. Exposing other bacteria to the tailocin, they found that while the strain that produced it was immune, many other strains growing in the same environment were killed by it. When the team deleted the genes that encode key parts of the tailocin, the killing went away.

The researchers hypothesize that the system is used to kill off potential competition but that many strains have evolved resistance to the tailocin.

When the researchers did a genetic screen to identify resistant mutants, they found that resistance was provided by mutations that interfered with the production of complex sugar molecules that are found on proteins that end up on the exterior of cells. At the same time, most of the genetic differences among the VC2 genes occur in the proteins that encode the legs, which latch on to these sugars.

So it appears that every bacterial strain is both an aggressor and a victim, and there’s an evolutionary arms race that leads to a complex collection of pairwise interactions among the strains—think of a rock/paper/scissors game with dozens of options. And the arms race has a history. Using old samples, the researchers show that many of the variations in these genes have been around for at least 200 years.

Evolutionary competitions are often viewed as a simple one-against-one fight, probably because it’s an easy way to think about them. But the reality is that most are more akin to a chaotic bar room brawl—one where it’s rare for any faction to obtain a permanent advantage.

Science, 2024. DOI: 10.1126/science.ado0713  (About DOIs).

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How the “Nutbush” became Australia’s unofficial national dance

cultural studies, dance, fads, human culture, line dancing, Nutbush, Science, Tina Turner / /

“A church house, gin house” —

Most Australians learned the “daggy” line dance in primary school starting in the mid-1970s

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Embassy employees, men and women, in a bee-shaped line formation doing the Nutbush

Enlarge / US Embassy Australia employees learning to do the Nutbush to honor the late Tina Turner in 2023.

The whole world mourned the passing of music legend Tina Turner last year, perhaps none more so than Australians, who have always had a special fondness for her. That’s not just because of her star turn as Aunty Entity in 1985’s Mad Max Beyond Thunderdome or her stint as the face of Australia’s rugby league.

Australians of all ages have also been performing a line dance called the “Nutbush” at weddings and social events to Turner’s hit single (with then-husband Ike Turner) “Nutbush City Limits.” Turner herself never performed the dance, but when she died, there was a flood of viral TikTok videos of people performing the Nutbush in her honor—including members of the US Embassy in Canberra, who had clearly just learned it for the occasion. Dancers at the 2023 Mundi Mundi Bash in a remote corner of New South Wales set a world record with 6,594 dancers performing the Nutbush at the same time.

The exact origin of the dance remains unknown, but researchers at the University of South Australia think they understand how the Nutbush became so ubiquitous in Australia, according to a paper published in the journal Continuum. “What we seem to know is that there was a committee in the New South Wales education department that devised the idea of the Nutbush,” co-author Jon Stratton told the Guardian. “Whether they devised the dance itself, we don’t really know. But what’s interesting is that nobody has come forward.”

“Nutbush City Limits” was released in 1973. However, the authors note that the song peaked at 87 on the Australian charts and didn’t appear at all throughout 1974—only to start charting again from March to May 1975 and again from June–October 1976, peaking at No. 14. (It charted once again last year when Turner died.) They suggest that “Nutbush City Limits” was a great “dance floor filler,” especially in the 1970s disco era, so people were purchasing the single over a longer period of time.

But another likely explanation was the spread and development of the dance now known as the Nutbush during this same time period, initially as an educational activity in Australian primary schools. An homage of sorts to Turner’s hometown (Nutbush, Tennessee), the song features a hard 4/4 stomp beat laid over a funk rhythm, making it ideal for a line dance. There are anecdotal reports of people doing the Nutbush to different tunes, like Starship’s “We Built This City” (1985), which also features a 4/4 beat.

Knee, knee, kick, kick

Dancing has been incorporated into education since the 1920s. “Line dances work very well in classrooms because the teacher can stand at the front and give instructions to the lines,” said Stratton. “The idea must have been to provide students with an enjoyable way of exercising and learning coordination. Whoever designed the Nutbush succeeded beyond any success they could have hoped for. What makes it special is that it’s moved out of schools to become the dance of choice at many Australian social events.”

It’s unique to Australia, but the Nutbush shares some similarities with the Madison—minus the calls—another popular line dance that emerged in the 1950s thanks to teen dance shows like American Bandstand and The Buddy Deane Show. (The latter inspired the 1988 John Waters film Hairspray.) In fact, in a 2016 Reddit thread, P.J. Fletcher suggested in 2016 that the Nutbush was actually a bastardized version of the Madison with misremembered steps and drew a faulty diagram of those steps. Fletcher traced its origin to 1978 when the New South Wales Department of Education launched primary school teacher retraining initiatives, initially for a Sydney school district and spreading to other regions from there.

Let’s do the Nutbush again.

Stratton and his co-author, Panizza Allmark, dismiss this theory. For one thing, they discovered that the Nutbush was already being taught at a technical school in Victoria in 1978, so the dance was already well-established by then, at least in Victoria. They suggest the dance originated in 1975 in New South Wales and spread from there. Also, the Madison is difficult to perform to 4/4 songs like “Nutbush City Limits” since it is based on a six-beat pattern. Thus, “One possibility is that somebody in the school system in Sydney developed the Nutbush because they found that school students had too much difficulty learning the Madison to make it either enjoyable or worthwhile,” the authors wrote.

“Unlike formal dancing where you needed a partner, the Nutbush didn’t involve holding hands or touching anyone of the opposite sex,” said Allmark, who danced the Nutbush herself as a primary school student in Perth in the early 1980s. “In primary school, when learning folk dancing, there was great awkwardness in having to dance with a partner of the opposite sex but with the Nutbush, you didn’t need ‘to take a partner by the hand.’ You could enjoy the dance moves and be part of a communal experience without all the sweaty handholding.”

Regardless of how the fad took hold, hearing the song’s opening bars and the lines “A church house, gin house” will likely keep bringing Aussies enthusiastically to the dance floor for years to come.

Continuum, 2024. DOI: 10.1080/10304312.2024.2331796  (About DOIs).

Ike and Tina Turner perform “Nutbush City Limits” in 1973.

How the “Nutbush” became Australia’s unofficial national dance Read More »

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SCOTUS rejects challenge to abortion pill for lack of standing

Abortion, mifepristone, miscarriage, reproductive health, Science, SCOTUS, Supreme Court / /

“Near miss” —

The anti-abortion defendants are not injured by the FDA’s actions on mifepristone.

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Mifepristone (Mifeprex) and misoprostol, the two drugs used in a medication abortion, are seen at the Women's Reproductive Clinic, which provides legal medication abortion services, in Santa Teresa, New Mexico, on June 17, 2022.

Enlarge / Mifepristone (Mifeprex) and misoprostol, the two drugs used in a medication abortion, are seen at the Women’s Reproductive Clinic, which provides legal medication abortion services, in Santa Teresa, New Mexico, on June 17, 2022.

The US Supreme Court on Thursday struck down a case that threatened to remove or at least restrict access to mifepristone, a pill approved by the Food and Drug Administration for medication abortions and used in miscarriage care. The drug has been used for decades, racking up a remarkably good safety record in that time. It is currently used in the majority of abortions in the US.

The high court found that the anti-abortion medical groups that legally challenged the FDA’s decision to approve the drug in 2000 and then ease usage restrictions in 2016 and 2021 simply lacked standing to challenge any of those decisions. That is, the groups failed to demonstrate that they were harmed by the FDA’s decision and therefore had no grounds to legally challenge the government agency’s actions. The ruling tracks closely with comments and questions the justices raised during oral arguments in March.

“Plaintiffs are pro-life, oppose elective abortion, and have sincere legal, moral, ideological, and policy objections to mifepristone being prescribed and used by others,” the Supreme Court noted in its opinion, which included the emphasis on “by others.” The court summarized that the groups offered “complicated causation theories to connect FDA’s actions to the plaintiffs’ alleged injuries in fact,” and the court found that “none of these theories suffices” to prove harm.

Weak arguments

The anti-abortion medical groups, led by the Alliance for Hippocratic Medicine, argued that the FDA’s relaxation of mifepristone regulations could cause “downstream conscience injuries” to doctors who are forced to treat patients who may suffer (rare) complications from the drug. But the court noted that there are already strong federal conscience laws in place that protect doctors who refuse to participate in abortion care. Further, the doctors failed to provide any examples of being forced to provide care against their conscience.

The plaintiffs further claimed “downstream economic injuries” by way of having to divert resources from other patients and services. But the court flatly knocked down this argument, too, noting that the argument is “too speculative, lacks support in the record, and is otherwise too attenuated to establish standing.” Further, the organizations claimed that the FDA’s actions “caused” them to conduct studies and “forced” them to engage in advocacy and outreach efforts. “But an organization that has not suffered a concrete injury caused by a defendant’s action cannot spend its way into standing simply by expending money to gather information and advocate against the defendant’s action,” the Supreme Court ruled.

In a response to the ruling, reproductive health rights group National Institute for Reproductive Health blasted the lower courts’ actions that brought the case to the Supreme Court and described it as a warning. “This case should never have made it to the Supreme Court in the first place,” Haydee Morales, interim president of NIRH, said in a statement. “Anti-abortion operatives brought this case with one goal in mind—to ban medication abortion and they failed. This case was a near miss for the science and medicine community and it won’t be the last attack.”

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May contain nuts: Precautionary allergen labels lead to consumer confusion

Features, food allergies, Science, undark / /

can i eat this or not? —

Some labels suggest allergen cross-contamination that might not exist.

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May contain nuts: Precautionary allergen labels lead to consumer confusion

TopMicrobialStock, Getty Images

When Ina Chung, a Colorado mother, first fed packaged foods to her infant, she was careful to read the labels. Her daughter was allergic to peanuts, dairy, and eggs, so products containing those ingredients were out. So were foods with labels that said they may contain the allergens.

Chung felt like this last category suggested a clear risk that wasn’t worth taking. “I had heard that the ingredient labels were regulated. And so I thought that that included those statements,” said Chung. “Which was not true.”

Precautionary allergen labels like those that say “processed in a facility that uses milk” or “may contain fish” are meant to address the potential for cross-contact. For instance, a granola bar that doesn’t list peanuts as an ingredient could still say they may be included. And in the United States, these warnings are not regulated; companies can use whatever precautionary phrasing they choose on any product. Some don’t bother with any labels, even in facilities where unintended allergens slip in; others list allergens that may pose little risk. Robert Earl, vice president of regulatory affairs at Food Allergy Research & Education, or FARE, a nonprofit advocacy, research, and education group, has even seen such labels that include all nine common food allergens. “I would bet my bottom dollar not all of those allergens are even in the facility,” he said.

So what are the roughly 20 million people with food allergies in the US supposed to do with these warnings? Should they eat the granola bar or not?

Recognizing this uncertainty, food safety experts, allergy advocates, policymakers, and food producers are discussing how to demystify precautionary allergen labels. One widely considered solution is to restrict warnings to cases where visual or analytical tests demonstrate that there is enough allergen to actually trigger a reaction. Experts say the costs to the food industry are minimal, and some food producers across the globe, including in Canada, Australia, Thailand, and the United States, already voluntarily take this approach. But in the US, where there are no clear guidelines to follow, consumers are still left wondering what each individual precautionary allergen label even means.

Pull a packaged food off an American store shelf and the ingredients label should say if the product intentionally contains one of nine recognized allergens. That’s because in 2004, Congress granted the Food and Drug Administration the power to regulate labeling of eight major food allergens—eggs, fish, milk, crustaceans, peanuts, tree nuts, soybeans, and wheat. In 2021, sesame was added to the list.

But the language often gets murkier further down the label, where companies may include precautionary allergen labels, also called advisory statements, to address the fact that allergens can unintentionally wind up in foods at many stages of production. Perhaps wheat grows near a field of rye destined for bread, for instance, or peanuts get lodged in processing equipment that later pumps out chocolate chip cookies. Candy manufacturers, in particular, struggle to keep milk out of dark chocolate.

The FDA offers no labeling guidance beyond declaring that “advisory statements should not be used as a substitute for adhering to current good manufacturing practices and must be truthful and not misleading.”

Companies can choose when to use these warnings, which vary widely. For example, a 2017 survey conducted by the FDA and the Illinois Institute of Technology of 78 dark chocolate products found that almost two-thirds contained an advisory statement for peanuts; of those, only about four actually contained the allergen. Meanwhile, of 18 bars that carried no advisory statement for peanuts specifically, three contained the allergen. (One product that was positive for peanuts did warn more generally of nuts, but the researchers noted that this term is ambiguous.) Another product that tested positive included a nut warning on one lot but not on another. Individual companies also select their own precautionary label phrasing.

For consumers, the inconsistency can be confusing, said Ruchi Gupta, a pediatrician and director of the Center for Food Allergy & Asthma Research at Northwestern University’s Feinberg School of Medicine in Chicago. In 2019, Gupta and colleagues asked around 3,000 US adults who have allergies or care for someone who does about how different precautionary allergen label phrases make a difference when they are considering whether to buy a particular food. About 80 percent never purchase products with a may contain warning. Less than half avoid products with labels suggesting that it was manufactured in a facility that also processes an allergen, even though numerous studies show that the wording of a precautionary allergen label has no bearing on risk level. “People are making their own decisions on what sounds safe,” said Gupta.

When Chung learned that advisory labels were unregulated, she experimented with ignoring them when her then-toddler really wanted a particular food. When her daughter developed a couple of hives after eating a cereal labeled may contain peanuts, Chung went back to heeding warnings of peanut cross-contact but continued ignoring the rest.

“A lot of families just make up their own rules,” she said. “There’s no way to really know exactly what you’re getting.”

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Ancient Maya DNA shows male kids were sacrificed in pairs at Chichén Itzá

Science / /

Tossed into the sacred sinkhole —

Twins play an auspicious role in Maya mythology, most notably in the Popol Vuh.

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Detail from the reconstructed stone tzompantli, or skull rack, at Chichén Itzá.

Enlarge / Detail from the reconstructed stone tzompantli, or skull rack, at Chichén Itzá, evidence of ritual human sacrifice.

Christina Warinner

Inhabitants of the ancient Maya city of Chichén Itzá are well-known for their practice of ritual human sacrifice. The most prevalent notion in the popular imagination is that of young Maya women being flung alive into sink holes as offerings to the gods. Details about the cultural context for these sacrifices remain fuzzy, so scientists conduced genetic analysis on ancient remains of some of the sacrificial victims to learn more. That analysis confirmed the prevalence of male sacrifices, according to a new paper published in the journal Nature, often of related children (ages 6 to 12) from the same household—including two pairs of identical twins.

Chichén Itzá (“at the mouth of the well of the Itzá”) is located in Mexico’s eastern Yucatán. It was one of the largest of the Maya cities, quite possibly one of the mythical capital cities (Tollans) that are frequently mentioned in Mesoamerican literature. It’s known for its incredible monumental architecture, such as the Temple of Kukulcán (“El Castillo”), a step pyramid honoring a feathered serpent deity. Around the spring and fall equinoxes, there is a distinctive light-and-shadow effect that creates the illusion of a serpent slithering down the staircase. There is also a well-known acoustical effect: clap your hands at the base of the staircases and you’ll get an echo that sounds eerily like a bird’s chirp—perhaps mimicking the quetzal, a brightly colored exotic bird native to the region and prized for its long, resplendent tail feathers.

The Great Ball Court (one of 13 at the site) is essentially a whispering gallery: even though it is 545 feet long and 225 feet wide, a whisper at one end can be heard clearly at the other. The court features slanted benches with sculpted panels depicting aspects of Maya ball games—which were not just athletic events but also religious ones that often involved ritual sacrifices of players by decapitation.

“Evidence of ritual killing is extensive throughout the site of Chichén Itzá and includes both the physical remains of sacrificed individuals as well as representations in monumental art,” the authors of the new Nature paper wrote. Decapitation was just one method of sacrifice favored by the Maya over various historical periods. The Maya were equally fond of cutting out the still-beating hearts of victims, accessing the organ either from below the diaphragm or through the sternum. There were also rituals that involved binding victims to a stake and shooting arrows at a white target painted on the heart.

The site features underground rivers with natural sinkholes, called cenotes, providing water to the local inhabitants. One of those is known as the Cenote Sagrado (“Sacred Cenote”), or the Well of Sacrifice, some 200 feet (60 meters) wide and surrounded by sheer cliffs. As its name implies, the Maya would regularly sacrifice valuable objects and the occasional human by tossing them into the sinkhole to appease the Maya rain god, Chaac. (If the 89-foot (27-meter) fall didn’t kill them, drowning would.)

We know this from the writings of Friar Diego de Landa, among others, who wrote in 1566 of the Maya custom of throwing men alive into the sinkhole during droughts, as well as other prized objects. Dredging the Sacred Cenote with a bucket-and-pulley system in the early 1900s yielded artifacts made of gold and jade, as well as pottery, incense, and human remains. There were also archaeological excavations in the 1960s that yielded even more such objects, including flint, shell, rubber, cloth, and wood preserved in the water.

El Castillo, also known as the Temple of Kukulcan, is among the largest structures at Chichén Itzá, and its architecture reflects its far-flung political connections.

Enlarge / El Castillo, also known as the Temple of Kukulcan, is among the largest structures at Chichén Itzá, and its architecture reflects its far-flung political connections.

Johannes Krause

Archaeologists also uncovered a full-scale stone representation of a massive tzompantli (skull rack) and a subterranean chamber near the Sacred Cenote, likely a repurposed water cistern (chultún) that had been enlarged to connect to a small cave. The Maya viewed both cenotes and chultúns as connections to the underworld, and this particular chultún housed the remains of over 100 children.

Rodrigo Barquera, an immunogeneticist and postdoc at the Max Planck Institute for Evolutionary Anthropology, and his fellow Nature co-authors conducted their in-depth genetic analysis on 64 child remains recovered from the chultún, along with stable isotope analysis of bone collagen and nitrogen and radiocarbon dating. They compared the genetic data to the genomes from blood samples taken from 68 present-day Maya residents of a nearby town (Tixcacaltuyub).

Most of the children had been sacrificed between 800 to 1000 CE, per the radiocarbon and nitrogen dating. Barquera et al. were surprised to find that all of the remains sampled were male and from the local Maya populations. Nearly one-quarter of those were closely related to at least one other child interred in the chultún, and the related children had similar diets, so were likely raised in the same household. The most surprising discovery: two sets of identical male twins. All this suggests that the Maya selected pairs of male children for sacrificial rituals associated with the chultún.

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