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Spokesperson for Taylor Fresh Foods told Reuters ‌that the company was informed FDA made a mistake

What is the parasitic illness cyclosporiasis?

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The US Food and Drug ⁠Administration said on Sunday that laboratory experts re-checked lettuce sample results from Taylor Farms in an ⁠investigation into an ⁠outbreak of the ​cyclospora parasite and concluded the finding should be considered a false positive.

As of Sunday, there were ⁠no confirmed positive sample results for cyclospora, the FDA added. The FDA on Saturday had said that a ⁠sample of shredded iceberg lettuce supplied by Taylor Farms tested positive ​for the parasitic illness that has ‌sickened thousands of ‌people in the US.

Guardian staff contributed

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It's long been debated what started the 1789 smallpox outbreak that devastated the Indigenous population in Australia. Now, a new modeling study has the likely answer: It was brought in 1788 by the "First Fleet" of British ships to settle Australia.

The finding is based on mathematical modeling of the disease's impact on Indigenous Australians and rejects a contrary idea that the outbreak originated through contact with Indonesian islanders fishing in the far North of the country.

Alan Williams — an archaeologist at the private firm EMM Consulting and co-author of the study, published July 9 in the journal Nature Human Behaviour ‪—‬ told Live Science that the likely source of the outbreak were vials of dried smallpox scabs that British medics kept for inoculations (a precursor of smallpox vaccines, which weren't invented by Edward Jenner until the 1790s).

Some historians had argued that the live smallpox virus could not have survived the eight-month ship journey from Portsmouth, England, to Botany Bay, south of what is now the modern city of Sydney, where the British ships first landed.

But the investigation showed that the vials of smallpox scabs may have been replenished during the voyage when the fleet stopped at either Cape Town, South Africa, or Rio de Janeiro, Brazil, only a few months earlier, Williams said.

The smallpox outbreak devastated Indigenous communities and contributed to the rapid demise of Indigenous Australian culture, he said. The study estimates approximately 220,000 people died from the disease, and that early-20th-century Australian authorities did not comprehend the true extent of the Indigenous population when they attempted to document historical accounts.

Mystery outbreak

Within a few decades of the British Royal Navy officer James Cook charting Australia, the British sent ships to settle the continent. The British "First Fleet" to Australia consisted of 11 ships: two naval vessels, six convict transports and three ships for provisions. The British claimed that Australia legally belonged to nobody. They soon left Botany Bay because the land and water there were poor, and they moved to Sydney Cove in Port Jackson, which is now part of modern Sydney. There, they raised the British flag, claiming the whole continent.

There were no signs of a smallpox outbreak among nearby Indigenous communities when the First Fleet arrived, but the disease took a devastating toll in the decades that followed. Because there were no recorded cases of smallpox on the fleet, it was argued that the disease must have arrived in Australia on the tropical north coast of the continent through contact with islanders from the Makassar region of Sulawesi, which is now part of Indonesia.

But the new computer modeling of the proposed north coast outbreak showed the disease could not have spread from there to Australia's Southeast. Among other issues, the two regions were separated by thousands of miles of uninhabited desert, Williams said. Meanwhile, modeling of the smallpox outbreak in Indigenous communities near Port Jackson indicated that the outbreak had originated there, the researchers found.

Co-author Matthew Cody Nitschke , an expert in computer modeling at Flinders University in Adelaide, told Live Science that it is now clear that the outbreak was very unlikely to have originated in the North; by contrast, "there is very strong evidence that it was the First Fleet."

At the time, disease theory was not known , so the spread of smallpox may have happened by accident, Williams said.

An Indigenous Australian man holds traditional weapons during a ceremonial dance in Laura Quinkan Dance Festival at Cape York, Australia. New estimates that the theoretical population capacity of Australia before the British arrival was up to 5 million Indigenous people. (Image credit: chameleonseye via Getty Images) Revising earlier ideas

The new study in Nature Human Behaviour refers to a second study by the same researchers that is now being prepared for publication by the same journal. It proposes that there were up to 3 million Indigenous Australians at the time the First Fleet arrived — many more than the 300,000 or so proposed in some earlier studies.

That second study, based in part on archaeological investigations of early Indigenous Australian communities, suggests that the theoretical population capacity of Australia before the British arrival was up to 5 million people, especially in the resource-rich areas of the North and Southeast.

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The former estimate of roughly 300,000 Indigenous Australians seems to have come from a study in the 1930s based only on their depleted numbers. "By the time people actually sat down and said how many people were here, we had 100 years of disease, frontier violence, and everything else going on," Williams said.

University of Tasmania historian Henry Reynolds , who was not involved in the studies, told Live Science that the research debunks the old idea that the smallpox outbreak started on the north coast. "The idea that it came from the North and arrived at exactly the time [as the First Fleet] was always improbable," he said.

Ann McGrath , a historian at the Australian National University in Canberra who was not involved in the work, agreed. "The strong interdisciplinary approach of this latest research convincingly refutes this, and it also provides a much expanded estimate of the Indigenous population prior to 1788," she said in an email.

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In looking back and commemorating the 50th anniversary of the Viking missions to Mars, one is struck by the bold and audacious undertaking.

Twin spacecraft missions — each consisting of a lander and an orbiter — made their way to Mars and into the history books. The Viking 1 lander planted its legs on the terrain of Chryse Planitia 50 years ago today, on July 20, 1976, while its Viking 2 counterpart touched down at Utopia Planitia on Sept. 3 of that year.

Among their duties, the dual landers scooped up the first soil samples of Mars and deposited those precious collectibles into onboard, specialized equipment. Viking scientists had designed that gear to help answer an intriguing question: Is there life on Mars ?

A model of NASA's Viking 1 lander here on Earth. On July 20, 1976, the spacecraft touched down on the surface of Mars. (Image credit: NASA) One of Viking's instruments was a GCMS, a combination of a gas chromatograph (GC) and a mass spectrometer (MS). A positive GCMS detection could confirm the possibility that organics needed for the origin of life as we know it were present.

After interpreting all the data and information gleaned from ingested Martian soil, most scientists at the time concluded that Viking relayed a "no life on Mars" result.

But is it possible that the two robots actually radioed back a very clear comeback: "Can you repeat the question ?"

Different techniques

Ben Clark was a member of the Viking science team, and the instrument he designed made the first-ever measurements of the chemical composition of Mars soil. He is now a senior research scientist at the Space Science Institute in Boulder, Colorado.

"There were three life-detection experiments, each using different techniques to probe whether they could stimulate biological activity in the soil by adding various selected nutrients," Clark told Space.com. "Two were generally negative in their findings, but a third experiment had an expected strong response when it added nutrient."

Indeed, astrobiologist/inventor Gilbert Levin remained convinced that his Viking microbial detection instrument, called the Labeled Release experiment, did find living microorganisms in the soil of Mars. He held tight to that view until he passed in July 2021 at the age of 97.

Skeptical scientists

Clark recalled that many members of the scientific community were skeptical when geochemists pointed out that certain minerals can cause a similar response.

"Furthermore, when a second amount of nutrient was added, there was no additional response," Clark said. "Did the organisms die between experiments ?"

Because of these responses, and especially because no organic molecules could be detected, most biologists concluded there was no life in the dirt that Viking tested. "However, there is also the question of whether the best nutrients were used in the Viking tests," Clark noted.

Microbiologists who study the small organisms that live in Earth soil, Clark added, know that some species are extremely adept at using sulfate as an energy source, by combining it with organics or with hydrogen gas.

"Unfortunately, none of the Viking life-detection experiments added hydrogen gas to their chambers," Clark said.

"Ironically, the instrument which searched for organics in the soil, the GCMS, used hydrogen gas in its analytical technique," he added. "Thus, there was a tank full of hydrogen gas located just centimeters away from the life-detection experiment package, but no connection between it and the GCMS where it was located."

This mosaic is made up of more than 100 images captured by NASA’s Viking 1 orbiter, which operated around Mars from 1976 to 1980. The scar across the center of the planet is the vast Valles Marineris canyon system. (Image credit: NASA/JPL-Caltech) True positive detections?

Even today, there are some scientists who question whether some of the life-detection experimental results were in fact true positive detections, according to Clark.

"Other scientists believe that it was not enough to simply test the loose soil, but that life in fact may be just centimeters below the surface in areas where there is still ice in the ground ," he said.

Clark said that no other planet in our solar system so closely matches the early history of our own planet Earth.

"Recent discoveries by the rovers now roaming Mars have revealed some detections of organic molecules, and even some so-called 'reduction spots,' which are interpreted by some geologists as evidence of activity of biological organisms ," he said.

Misunderstood results

Steven Benner is an astrobiochemist and director of the Foundation for Applied Molecular Evolution in Alachua, Florida. He is author of the soon-to-be-issued "Meet the Neighbors: Life on Mars and How to Find It" (Penguin Press, 2026).

Benner has long argued that the results from Viking were misunderstood. He contends that the Red Planet remains an easily reached destination to discover a possible independent origin of life and draws upon the Viking records to spotlight how the scientific process has failed in this regard to date.

Tied to Viking's 50th anniversary, "I decided to write a grumpy 'take no prisoners' book that dispenses with politeness and focuses on the facts," Benner told Space.com.

Viking flyer from NASA Langley Research Center. The spacecraft were built by Martin Marietta with Langley in Hampton, Virginia managing the Viking project. The Jet Propulsion Laboratory handled the operations of the probes once in flight. (Image credit: Langley Research Center/The Viking Mars Missions Education and Preservation Project) Misbegotten consensus

Benner said that his new book highlights two tales.

"Viking more likely than not found autotrophic microbial life on Mars, roughly 1,000 cells per gram — about what you might expect based on Earth analogs," said Benner.

The other story, he said, is that communities will defend a misbegotten "consensus" long after that consensus ceases to be defensible. They should not be beholden to a half century of mistakes, he emphasized.

The GCMS misinterpretation was 100% of the grounds for dismissing considerable life-positive data, according to Benner. So, he said, "we should then have gone back to the status quo ante, as Gil Levin did. But since 'consensus' in science is powerful, and Levin was polite, the community marginalized him."

Viking preservation

Rachel Tillman is the founder and executive director of the nonprofit Viking Mars Missions Education and Preservation Project .

Her late father, James Tillman, worked on Viking 1 and 2 and was a professor in the Department of Atmospheric Sciences at the University of Washington.

"There are a variety of reasons it's important to preserve Viking data," Tillman told Space.com. Archiving how and why things were done on Viking from an engineering standpoint is vital, she said, as is safeguarding the science data accumulated during the Viking program.

"Science is dynamic. Instruments and missions are finite in what they collect, so every data is part of a growing body of knowledge coming in pieces of a much larger puzzle. We can't complete the puzzle without all of the data," said Tillman. "So every facet of Mars science is a tiny piece of the puzzle. For that reason, we need to keep all the pieces."

This is true of every engineering success and failure, she added.

"Our organization has records on both. Because of that, we can help industry reduce costs by making the archives available on failed tests as much as successful ones," Tillman said.

It takes many, many missions to get close to answers we theorize on, she pointed out. "And then there is inspiration. By preserving the past — the who, what and how — we inspire youth and the public to support endeavors and even join the workforce," she concluded.

Space technicians prepare the Viking 1 lander, encased in its bioshield, for its sterilization. (Image credit: NASA) Contaminate and confuse

"The entire Viking mission — orbiters and landers — are one of the most important sets of data about the planet Mars," said Barry DiGregorio, an honorary research fellow for the Buckingham Center for Astrobiology in the United Kingdom. He is author of "Mars: The Living Planet" (Frog Books/1997).

"Indeed, the Viking biology data have become more important today than they were during the Viking mission," said DiGregorio. "Because Viking carried the very first suite of extant biology instruments to Mars, extreme care was given to the extensive heat sterilization protocols for the Viking landers."

Those protocols ensured that the Vikings did not carry large numbers of terrestrial microorganisms that might contaminate and confuse the actual soil sample results in its three onboard life-detection instruments, DiGregorio said.

Warning flag

However, DiGregorio is also waving a warning flag.

The recent discovery of never-before-detected extremophile microbes in spacecraft assembly clean rooms has made it important to take planetary protection protocols to a new level, said DiGregorio.

"Unfortunately, the search for extant life on Mars has been made much more difficult by unwittingly sending Earth's hardiest extremophile microorganisms there for the last 30 years," he said.

If Mars life is indeed spotted, extra effort will be required "to make sure it isn't earthly extremophile microbes we are detecting," DiGregorio added.

Both Viking landers ceased operating more than four decades ago. But they could still aid the Mars life search today, according to DiGregorio. Perhaps, he said, "comparing any new data found with archived Viking Lander biology data will be crucial in determining their interpretation."