Author: chemistadmin

Humans have long imagined what it would be like to see the world through different eyes. In Greek and Roman mythology, for example, the giant Argus Panoptes used his dozens of eyes to keep watch. The poet Ovid reported that they acted in independent pairs, with two at a time going to sleep while the rest remained alert.

A smaller many-eyed mystery fascinates scientists today: members of the family Salticidae, or jumping spiders, with their front pair of large, round eyes and three smaller peepers on each side of their head. A new study explores how these arachnids see—and, more specifically, what they care about seeing. Understanding how their eyes work together may inform future technologies, and offer a glimpse into a very different being’s perception.

“The results are indicative of cognitive processes that are sifting the world into categories of what is interesting—what is worth turning toward and investigating further, and what is not—what can be dismissed or ignored or kept in the corner of one’s eye,” says Nathan Morehouse, a University of Cincinnati biologist, who studies jumping spider vision and was not involved in the study. “These are really questions about alien minds.”

The “Cats of the Invertebrate World”

When Ximena Nelson teaches about these spiders at the University of Canterbury in New Zealand, she likes to do an experiment with her students. She warns them that she is about to project a vivid close-up of a jumping spider’s face on a large screen at the front of the room and then watches as even the self-described arachnophobes coo with delight, as if they were seeing a seal pup.

The spiders “are so relatable to us because they’ve got big eyes, and they look at you,” says Nelson, an animal behavior researcher. She reviewed the new study but was not involved in the work.

Beyond their endearing aspect, however, it is these spiders’ unusual behavior that makes them rewarding research subjects—especially when studying perception. Unlike many arachnids, jumping spiders do not build webs or stay in one place. They scan their environment for prey, stalk it and then pounce to capture it. Ron Hoy, a Cornell University professor emeritus, who studies jumping spider neurology and was not involved with the research, says they act more like predatory felines. In fact, he says, the late influential neurologist Michael Land liked to call jumping spiders the “cats of the invertebrate world.”

The spiders’ near-360-degree eyesight helps them spot prey and hunt. But while their two large front eyes, called anterior medial eyes, have high acuity, those eyes’ field of vision is small. The lenses of the spiders’ eyes cannot swivel like those of humans, so when the arachnids want to shift their gaze, they simply reorient their entire body in the time it takes us to glance sideways. They pivot to face objects of interest (including potential prey, threats or mates) that they first spot with two of their less acute side-facing pairs of eyes, called the anterior and posterior lateral eyes.

This behavior led many scientists to think of these side eyes as mere motion detectors. But Massimo de Agró, now a researcher at the University of Regensburg in Germany, suspected they did more: the spiders seemed to use their lateral eyes to pick and choose what they turned toward. De Agró is the first author of the new study, which was published on Thursday in PLOS Biology and was based on experiments he conducted as a fellow at Harvard University.

Miniature Treadmills and a Light Show

Studying a jumping spider’s image processing is not as straightforward as implanting electrodes in its brain, as scientists might do with a larger animal. Not only is the spiders’ brain the size of a poppy seed, but these animals use hydrostatic pressure to extend their legs—this makes their whole body a bit like a “walking water balloon” that could pop from any invasive procedure, Morehouse says.

To track where jumping spiders were looking, de Agró and his co-authors used a popular technique for studying bumblebees and other small invertebrates. They floated a tiny, patterned ball on a cushion of upward-blowing air. Spiders were placed atop the ball and held in place from above. When they tried to turn their body by moving their legs, they would stay in place, but the ball would rotate, acting a little like a treadmill. A video camera recorded the ball’s movement and thus the spiders’ intended motion.

The researchers then simultaneously displayed two images in each spider’s periphery and noted which one it tried to turn toward in order to gauge which image it was more interested in investigating. One of the images tested was a series of moving dots that represented the “biological motion” of a spider walking from a side view—which the researchers were excited to find the arachnids could distinguish from randomly moving dots.

Hoy compares this abstraction to the “green screen” suits and white dots worn by actors when creating special effects for movies and TV shows: human brains will recognize a series of dots moving a certain way as human motion even before movie magic turns the dots into a superhero or zombie. “It’s very well known for humans, of course, that they can capture motion by abstract dots,” he says. “But the fact that they’re showing that this is also true for jumping spiders is pretty remarkable.”

De Agró, a psychologist by training, says this phenomenon was first described in humans in the 1970s—but that nobody had imagined invertebrates might be able to process the same abstraction. In addition to showing his spiders biological motion, he also created a dot display with a scrambled version of that same motion (which other animals have been shown to interpret as living movement, despite the scrambling) and another with random motion. All were shown to the arachnids’ anterior lateral eyes.

The spiders showed no preference between the biological and scrambled motion—yet they strongly preferred the random motion to either. De Agró says this result initially dismayed him because the random dots had been meant as a control that the spiders would not care to investigate.

“I was so sad when I saw the results of that first condition,” he says. “I was thinking, ‘What’s happening here? It’s clear there’s nothing happening.’” But then the spiders’ preferences stayed consistent across the other conditions.

De Agró concluded that the spiders may turn toward a moving image when they want more information about it—implying that the anterior lateral eyes not only detect motion but also give a jumping spider enough data to classify the motion into categories of living (spider dots and scrambled spider dots) and unknown (random dots).

Nelson says this study had an elegant design and surprising results. She also wonders whether male and female spiders might show different responses to these stimuli because females are much more focused on finding food, whereas males are singularly obsessed with finding a mate.

De Agró adds that he hopes the study will help arachnophobes see these spiders in a new light, especially given the invertebrates’ capability to engage in the kind of visual processing once presumed available only to humans and other mammals.

Learning how animals’ eyes function differently from ours may also widen the perspectives of programmers and robotics designers. Researchers have already created depth sensors—which can be used in video games, cars and phones—that were inspired by the way jumping spiders’ eyes work. Hoy says future iterations of these designs may benefit robots’ visual sensors on unfamiliar terrain, whether flying through a rain forest or exploring the surface of an extraterrestrial planet.

“Figuring out how that computation is made in an animal that has already outsourced a task to different eyes,” Hoy says, “would be a great way to think about how to design robots that have to navigate in an unpredictable, visually cluttered world.”

Astronaut Scott Kelly famously spent an entire year residing onboard the International Space Station (ISS), about 400 kilometers above Earth, and his NASA colleague Christina Koch spent nearly that long “on station.” Each returned to Earth with slightly atrophied muscles and other deleterious physiological effects from their extended stay in near-zero gravity. But another, more insidious danger lurks for spacefarers, especially those who venture beyond low-Earth orbit.

Space is filled with invisible yet harmful radiation, most of it sourced from energetic particles ejected by the sun or from cosmic rays created in extreme astrophysical events across the universe. Such radiation can damage an organism’s DNA and other delicate cellular machinery. And the damage increases in proportion to exposure, which is drastically higher beyond the protective cocoon of Earth’s atmosphere and magnetic field (such as on notional voyages to the moon or Mars). Over time, the accrued cellular damage significantly raises the risk of developing cancer.

To address the situation, at NASA’s request, a team of top scientists organized by the National Academies of Sciences, Engineering, and Medicine published a report in June recommending that the space agency adopt a maximum career-long limit of 600 millisieverts for the space radiation astronauts can receive. The sievert is a unit that measures the amount of radiation absorbed by a person—while accounting for the type of radiation and its impact on particular organs and tissues in the body—and is equivalent to one joule of energy per kilogram of mass. Scientists typically use the smaller (but still quite significant) quantity of the millisievert, or 0.001 sievert. Bananas, for instance, host minute quantities of naturally occurring radioactive isotopes, but to ingest a millisievert’s worth, one would have to eat 10,000 bananas within a couple of hours.

Every current member of NASA’s astronaut corps has received less than 600 millisieverts during their orbital sojourns, and most, including Koch, have received much less and can thus safely return to space. But a year on the ISS still exposes them to more radiation than experienced by residents of Japan who lived near the Fukushima Daiichi nuclear accidents of 2011.

“Everybody is planning trips to the moon and Mars,” and these missions could have high radiation exposures, says Hedvig Hricak, lead author of the report and a radiologist at Memorial Sloan Kettering Cancer Center in New York City. Using current spaceflight-proved technologies, long-distance voyages—especially to the Red Planet—would exceed the proposed threshold, she says.

That could be a big problem for NASA’s Artemis program, which seeks to send astronauts to the moon in preparation for future trips to Mars. Another problem for the space agency is that the epidemiological data it uses mostly come from a longevity study of Japanese survivors of atomic bomb blasts, as well as from the handful of astronauts and cosmonauts who have endured many months or even years in low-Earth orbit. NASA’s current space radiation limit, which was developed in 2014, involves a complicated risk assessment for cancer mortality that depends on age and sex, yet more relevant data are necessary, Hricak argues. In the atomic bomb survivor study, for instance, women were more likely to develop lung cancer than men, suggesting a greater sex-based vulnerability to harmful radiation. “But with the knowledge we presently have, we know we cannot make a comparison between high exposure versus chronic exposure,” Hricak says. “The environment is different. There are so many factors that are different.”

NASA wants to update its standards now because the agency is on the cusp of sending so many astronauts well beyond low-Earth orbit, where greater amounts of space radiation seem destined to exceed previously mandated exposure limits. Furthermore, Hricak says, having a single, universal radiation limit for all space travelers is operationally advantageous because of its simplicity. A universal limit could also be seen as a boon for female astronauts, who had a lower limit than men in the old system and therefore were barred from spending as many days in space as their male counterparts.

The new radiation limit proposed by Hricak and her team is linked to the risks to all organs of a 35-year-old woman—a demographic deemed most vulnerable in light of gender differences in the atomic bomb survivor data and the fact that younger people have higher radiation risks, partly because they have more time for cancers to develop. The goal of the radiation maximum is to keep an individual below a 3 percent risk of cancer mortality: in other words, with this radiation limit, at most three out of 100 astronauts would be expected to die of radiation-induced cancer in their lifetime.

“NASA uses standards to set spaceflight exposure limits to protect NASA astronauts’ health and performance, both in mission and after mission,” says Dave Francisco of NASA’s Office of the Chief Health and Medical Officer. He acknowledges that, while astronauts on Mars missions would benefit from the thin Martian atmosphere that provides some limited protection, “transit in deep space has the highest exposure levels.”

That means long-haul space trips come with the biggest risks. A stay on the lunar surface for six months or more—presuming, of course, that astronauts eventually have a presence there and do not spend most of their time in subsurface habitats—would involve nearly 200 millisieverts of exposure, a higher amount than an extended visit to the ISS. And an astronaut traveling to Mars would be exposed to even more radiation. Whether they reached the Red Planet through a lunar stopover or on a direct spaceflight, they could have experienced significant radiation exposure en route. Even before they embarked on the trip back home, they could have already exceeded the 600 millisievert limit. The entire voyage, which would likely last a couple of years, could involve well more than 1,000 millisieverts. So if astronauts—and not just robots—will be sent to Mars, NASA likely will need to request waivers for them, Hricak says, although the exact process for obtaining a waiver has not yet been laid out.

The report’s proposal for a new radiation maximum is not without its critics. “For a mission to Mars, a 35-year-old woman right at that limit could have an over 10 percent chance of dying in 15 to 20 years. To me, this is like playing Russian roulette with the crew,” says Francis Cucinotta, a physicist at the University of Nevada, Las Vegas, and former radiation health officer at NASA. Despite the supposed benefits the new limits would have for female astronauts, he is concerned that the risks are particularly pronounced for younger women in space.

On the contrary, Hricak says, in its request for new limits, NASA has sought to be conservative. The European, Canadian, and Russian space agencies all currently have a higher maximum allowed dose of 1,000 millisieverts, while Japan’s limit is age- and sex-dependent like NASA’s current one, mainly because of a shared dependence on the atomic bomb survivor data.

But unlike someone in the vicinity of a nuclear explosion, the risk to an astronaut exposed to space radiation is long-term rather than immediate. Without proper shielding (which tends to be rather heavy and thus prohibitively expensive to launch) their chances of developing cancer, as well as cardiovascular disease, cataracts and central nervous system damage, slightly increase each day they are in space. In a person’s cells, space radiation can sever both strands of a DNA molecule’s double helix. And while a few such instances might come with very limited risks, each additional severance raises the odds of developing a harmful mutation that could cause cancer.

Fortunately, however, the body has ways of repairing some kinds of DNA damage, and it is possible to study that DNA repair in space, as was demonstrated by a new study published in the journal PLOS ONE in late June.

“This experiment set up a bunch of techniques that have never been implemented before in the very complex environment of the International Space Station,” says Sebastian Kraves, a co-founder of the Genes in Space student competition, which produced the investigation, and a co-author of the study. Using yeast cells onboard the ISS, Koch herself performed the experiment, which could become a precursor to future attempts to carefully monitor DNA damage and cellular repair in astronauts.

In addition to medical technologies, propulsion systems and shielding to protect against space radiation will likely advance as well. Particles expelled from the sun, for example, could be blocked with a few centimeters of aluminum or other materials, though astronauts outside their spacecraft or outside future lunar or Martian structures would be vulnerable. And they cannot be as easily shielded from more energetic cosmic radiation sources, such as heavy ions originating from distant exploding stars.

In any case, considering how little is known about various health risks from different kinds of space radiation, compared with radiation we are familiar with on Earth, researchers will surely continue with more studies like these to protect astronauts as much as possible. “I can tell you exactly how much exposure you’re going to get from a CT scan,” Hricak says, “but there are many uncertainties with space radiation.”

By Dana Gold & Lauren Kurtz

From political manipulation of COVID-19 research to censorship of weather forecasters who tried to contradict President Trump’s false claims about Hurricane Dorian, the Trump years were punctuated by jaw-dropping episodes of scientific misconduct.

But those are just the cases that couldn’t be covered up. There were countless more that were never made public. That’s why we’ve set up a safe and confidential way to report issues, including those that may still be happening. That way federal scientists as well as grantees, contractors and others employed outside the federal government have a way to safely speak out.

Because even though Trump is out of office, the problem isn’t solved. Claims of political interference in science are hardly new, and allegations have been made under Democratic administrations as well as Republican. But the scope and scale reached a fever pitch under the Trump administration, as various trackers and reports have documented. They list hundreds of publicly reported incidents, but that’s just the tip of the iceberg. Anonymous survey data indicate the true number is well into the thousands.

There are multiple examples of scientists who chose to speak out publicly about assaults on scientific integrity, typically after trying to raise concerns internally first without success and after facing retaliation.

Immunologist Rick Bright, who headed the Biomedical Advanced Research and Development Authority, blew the whistle on the Trump administration’s unwillingness to prepare for the coronavirus pandemic and promotion of bogus drug therapies. Maria Caffrey was a climate scientist with the National Park Service who pushed back internally on repeated and aggressive attempts to censor references to human-caused climate change. Both suffered professional reprisal for defending scientific integrity. And they are hardly alone.

Our respective organizations, the Climate Science Legal Defense Fund and Government Accountability Project, provided legal support to far more science professionals than we can disclose, faced threats to science during the Trump administration. While some felt comfortable enough to publicly report their concerns, the vast majority ultimately decided not to come forward—rightly fearing retaliation and doubting that speaking up would make a difference, particularly during an administration overtly hostile to both whistleblowers and science. Indeed, policies instituted by the Obama administration, in response to the George W. Bush administration’s corruption of science, failed to predict and protect against how brazen the next administration would be.

The Trump administration provided a serious stress test, and most scientific integrity policies failed. In the aftermath, we must investigate, because it is only in reviewing the failures that we will fully learn how to prevent them from happening again.

Recognizing this, President Biden issued a memorandum on scientific integrity after a week in office that kickstarted a multiyear effort to better protect federal research. It formed an interagency task force to review where scientific integrity policies have fallen short, which is scheduled to release its findings in September. But even amid current reform efforts, federal employees may still not be comfortable reporting past violations; fear of retaliation continues, particularly as a number of perpetrators are still working within the government as career civil servants.

To truly achieve a thorough review, even the most cautious and reluctant whistleblowers must feel comfortable coming forward. To this end, we launched the Scientific Integrity Reporting Project to provide a confidential, anonymous platform for scientists and others to detail threats to scientific integrity. We plan to draw upon the examples to inform policy makers about how to better protect science in the future.

This project will provide a necessary and important complement to the processes underway in the federal government. In addition to providing scientists with enhanced confidentiality safeguards, we hope our efforts will produce a broader range of responses. Current efforts appear to focus on the Trump and Obama administrations, but we are interested in examples extending both further back and further forward in time to better understand long-term and ongoing issues. We are also explicitly seeking to include experiences of people who work with but not for the federal government and who may be aware of a wider range of scientific integrity violations and willing to share their stories too.

The politicization of science undermines public trust in critical scientific institutions and has devastating consequences for public health and safety, as vividly illustrated by the tragic fallout from the Trump administration’s mishandling of the COVID-19 pandemic.

The Biden administration has recognized that a thorough accounting is needed for effective reforms, and it needs to look deep. By sharing their reports of assaults on scientific integrity they witnessed in the past, employees in and around federal science and across all disciplines can truly help protect the future.

Just as only narrowly avoiding the tip of an iceberg will still crash your boat into what’s concealed beneath the waves, if the Biden administration only addresses the breaches of scientific integrity so egregious they couldn’t be covered up, we’ll still be in dangerous waters.

This is an opinion and analysis article; the views expressed by the author or authors are not necessarily those of Scientific American.