theconversation.com – Jonathan Losos, William H. Danforth Distinguished University Professor, Arts & Sciences at Washington University in St. Louis – 2024-08-05 08:44:38
I’m an evolutionary biologist who has spent my career studying the evolution of small lizards in the Caribbean. I’m also a lifelong cat lover, but it never occurred to me to do anything scientific with house cats. They’re hard to study โ ever tried to follow your cat around to see what they’re doing? And in contrast to amply studied lions, tigers and other wild felines, I was under the impression that there wasn’t any interesting research being conducted on the domestic representative of the cat clan, Felis catus.
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Twelve years ago, I learned that I was completely wrong. Thanks to John Bradshaw’s book โCat Senseโ and the BBC’s โThe Secret Life of the Cat,โ I discovered that ailurologists were using the same cutting-edge methods โ GPS tracking, genome sequencing, isotopic analysis โ to study domestic cats that I use to study lizards and other researchers use with all manner of other creatures.
Thus was born my class on the science of cats. I’d lure students in with their love of felines and then, when they weren’t looking, I’d teach them how scientists study biodiversity โ ecology, evolution, genetics and behavior.
What does the course explore?
In essence, the course is about the past, present and future of cats: where they came from, why they do what they do, what the future may hold. And, critically, how we know what we know โ that is, how scientists address these sorts of questions.
The course concludes with students writing an original paper or making a mini-documentary. These projects have spanned a vast range of topics in biology and beyond, such as the impact of cats on bird populations, sexism and the crazy cat lady trope, the health effects pro and con of living with felines, the role of hybridization as a creative or constraining force in evolution, the top-down role of larger predators like coyotes and dingoes in controlling cat numbers, and the prospects for new genetic technologies to create allergen-free cats or to curb free-roaming cat populations.
Society needs more biodiversity scientists to understand our rapidly changing world. Cats pose scientific questions of broad interest, and they may serve as a gateway introduction to the world of biological research.
What’s a critical lesson from the course?
Important research on the natural world does not require traveling to remote corners of the world. Research on common animals in local surroundings โ even household pets โ can make important advances in basic and applied knowledge.
What materials does the course feature?
In addition to reading research papers, we took field trips that were both eye-opening and fun. We went out at the crack of dawn to join a homeless-cat advocate feeding unowned felines in a rundown part of town. We also learned about cats in ancient times from an Egyptologist, traveled to a cat show to marvel at the diversity of cat breeds, observed wild felines at the Saint Louis Zoo and examined cats in art at university museums.
What will the course prepare students to do?
Cat research is the vehicle for students to see the applicability of scientific ideas to animals they know and care for greatly. The course not only requires students to synthesize knowledge from many different fields, but also gets them to think about real-world contemporary debates, such as what to do about outdoor cats and the ethics of breeding.
What happens to a dead body in an extremely cold environment? Does it decompose? How do these conditions affect how forensic scientists understand when the person died?
Estimating time of death, also called the post-mortem interval, is a complex task. It plays an important role in forensic investigations, as it can provide critical insights into the timeline of events leading up to a person’s death. This information can narrow down potential scenarios and suspects, aiding in the resolution of criminal cases.
A multitude of factors are at play at a death scene, ranging from environmental conditions to the individual’s health status prior to death. Historically, scientists have estimated time of death by observing post-mortem physical and biological changes in the body, such as stiffening, fluid collection and cooling.
These methods are limited, however, by their variability and dependence on external factors. Calculating the post-mortem interval became more precise with the advent of molecular biology. But it’s still a challenging task, especially in extreme cold weather conditions. There is often a lack of obvious signs of decomposition on a frozen body during the first months after death.
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We are forensic scientists leading the forensics programs at the University of North Dakota and the University of Central Lancashire. We use molecular biology and bioinformatics to develop tools to help researchers and investigators more accurately estimate the post-mortem interval. Our recently published research in Frontiers in Microbiology found that studying the microbes involved in decomposition could predict time elapsed since death in extreme cold conditions with high accuracy.
In an extremely cold environment like North Dakota’s winters, traditional methods might not be enough to understand decomposition and estimate time of death. For instance, the body cools much faster in cold conditions, which can skew estimates based on body temperature.
Similarly, cold environments can delay the onset and duration of rigor mortis, or body stiffening. The process of decomposition, including the activity of insects and other scavengers that contribute to the breakdown of the body, can also be slowed or halted by freezing temperatures.
Snow is another important factor when investigating decomposition. It can insulate a body by trapping residual heat and raising its temperature slightly higher than the surrounding environment. This insulating effect allows the body to decompose at a slower rate compared with bodies exposed to open air.
Microbes and time since death
In conditions of extreme cold, it becomes necessary to employ additional means to understand decomposition and estimate the time of death. Advanced molecular techniques, such as analyzing the microbiome, gene expression and protein degradation, can help provide valuable information about the crime scene.
Each organism has distinct microbial characteristics that act like a fingerprint. The necrobiome, a community of microbes associated with decomposing remains, plays a crucial role in decay. Specific microbes are present during different stages of decomposition, contributing to the breakdown of tissues and the recycling of nutrients. Forensic investigators can sample what microbes are living in a dead body to deduce how long ago a person died based on the makeup of the microbial population.
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Our study focused on identifying common patterns in the microbial changes that occur during decomposition in extreme cold environments. Over a period of 23 weeks, we collected and analyzed 393 samples of microbes from the inside and outside of the noses dead pigs covered in snow. Pigs decompose similarly to humans and are commonly used in forensic research. We developed models to estimate the post-mortem interval by pairing microbial genetic data with environmental data such as snow depth and outdoor temperature.
Overall, we found that the bacterial species Psychrobacter, Pseudomonas and Carnobacterium may best predict time after death in extreme winter conditions up to six months after death, with a margin of error of just over nine days.
We found that different bacterial species are most abundant at different time intervals. For example, levels of Psychrobacter increase five weeks after death and are most abundant at 10 weeks, while Pseudomonas increase between five to nine weeks and hit a peak at 18 weeks.
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Improving forensics
Death is often an unpleasant topic to bring into a conversation. But from a forensic perspective, having techniques and methods to determine when someone has died can help bring justice and peace for loved ones.
Our study found that decomposition does not completely halt even in cold environments. Studying the microenvironment โ the local conditions surrounding the body, including temperature, humidity and microbial activity โ can reveal crucial information about the decomposition process. The key microbial species we identified served as biomarkers of death, allowing us to develop time-of-death models that researchers can use to overcome the limitations of just visually examining remains.
Microbes can become a crucial piece of the puzzle during the process of investigating a death by aiding in constructing more precise timelines, even in extreme conditions.
The Food and Drug Administration implemented a rule to go into effect on Sept. 10, 2024, requiring mammography facilities to notify women about their breast density. The goal is to ensure that women nationwide are informed about the risks of breast density, advised that other imaging tests might help find cancers and urged to talk with their doctors about next steps based on their individual situation.
The FDA originally issued the rule on March 10, 2023, but extended the implementation date to give mammography facilities additional time to adhere.
Breast density is categorized into four categories: fatty, scattered tissue, heterogeneously dense or extremely dense.
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Dense breasts are composed of more fibrous, connective tissue and glandular tissue โ meaning glands that produce milk and tubes that carry it to the nipple โ than fatty tissue. Because fibroglandular tissue and breast masses both look white on mammographic images, greater breast density makes it more difficult to detect cancer. Nearly half of all American women are categorized as having dense breasts.
The FDA now requires specific language to ensure that all women receive the same โaccurate, complete and understandable breast density information.โ After a mammogram, women must be informed:
โ That for those with dense breasts, additional imaging tests might help find cancer
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They must also be advised to discuss their individual situation with their health care provider, to determine which, if any, additional screening might be indicated.
The FDA standardized the information women must receive. It is written at an eighth grade reading level and may address racial and literacy-level differences in women’s knowledge about breast density and reactions to written notifications.
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For instance, our research team found disproportionately more confusion and anxiety among women of color, those with low literacy and women for whom English was not their first language. And some women with low literacy reported decreased future intentions to undergo mammographic screening.
What is the value of additional screening?
Standard mammograms use X-rays to produce two-dimensional images of the breast. A newer type of mammography imaging called tomosynthesis produces 3D images, which find more cancers among women with dense breasts. So, researchers and doctors generally agree that women with dense breasts should undergo tomosynthesis screening when available.
There is still limited scientific evidence to guide recommendations for supplemental breast screening beyond standard mammography or tomosynthesis for women with dense breast tissue. Data shows that supplemental screening with ultrasound, MRI or contrast-enhanced mammography may detect additional cancers, but there are no prospective studies confirming that such additional screening saves more lives.
So far, there is no data from randomized clinical trials showing that supplemental breast MRIs, the most often-recommended supplemental screening, reduce death from breast cancer.
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However, more early stage โ but not late-stage โ cancers are found with MRIs, which may require less extensive surgery and less chemotherapy.
Various professional organizations and experts interpret the available data about supplemental screening differently, arriving at different conclusions and recommendations. An important consideration is the woman’s individual level of risk, since emerging evidence suggests that women whose personal risk of developing breast cancer is high are most likely to benefit from supplemental screening.
Because personal risk of breast cancer is a crucial consideration in deciding whether to undergo supplemental screening, women should understand their own risk.
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The American College of Radiology recommends that all women undergo risk assessment by age 25. Women and their providers can use risk calculators such as Tyrer-Cuzick, which is free and available online.
Women should also understand that breast density is only one of several risks for breast cancer, and some of the others can be modified. Engaging in regular physical activity, maintaining a healthy weight, limiting alcohol use and eating a healthy diet rich in vegetables can all decrease breast cancer risk.
Are there potential harms?
Amid the debate about the benefits of supplemental breast screening, there is less discussion about its possible harms. Most common are false alarms: results that suggest a finding of cancer that require follow-up testing. Less commonly, a biopsy is needed, which may lead to short-term fear and anxiety, medical bills or potential complications from interventions.
MRI screening also involves use of a chemical substance called gadolinium to improve imaging. Although tiny amounts of gadolinium are retained in the body, the FDA considers the contrast agent to be safe when given to patients with normal kidney function.
MRIs may also identify incidental findings outside the breast โ such as in the lungs โ that warrant additional concern, testing and cost. Women should consider their tolerance for such risks, relative to their desire for the benefits of additional screening.
The out-of-pocket cost of additional screening beyond a mammogram is also a consideration; only 29 states plus the District of Columbia require insurance coverage for supplemental breast cancer screening, and only three states โ New York, Connecticut and Illinois โ mandate insurance coverage with no copays.
To address this knowledge deficit in some health care settings, radiologists, whose screening guidelines are more stringent than some other organizations, sometimes provide a recommendation for supplemental screening as part of their mammography report to the provider who ordered the mammogram.
Learning more about the topic in advance of a discussion with a provider can help a woman better understand her options.
Armed with information about the complexities of breast density and its impact on breast cancer screening, women can discuss their personal risk with their providers and evaluate the options for supplemental screening, with consideration of how they value the benefits and harms associated with different tests.
The Boeing Starliner has returned to Earth without its crew โ a former astronaut details what that means for NASA, Boeing and the astronauts still up inย space
Boeing’s crew transport space capsule, the Starliner, returned to Earth without its two-person crew right after midnight Eastern time on Sept. 7, 2024. Its remotely piloted return marked the end of a fraught test flight to the International Space Station which left two astronauts, Butch Wilmore and Sunita โSuniโ Williams, on the station for months longer than intended after thruster failures led NASA to deem the capsule unsafe to pilot back.
Wilmore and Williams will stay on the International Space Station until February 2025, when they’ll return to Earth on a SpaceX Dragon capsule.
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The Conversation U.S. asked former commander of the International Space Station Michael Fossum about NASA’s decision to return the craft uncrewed, the future of the Starliner program and its crew’s extended stay at the space station.
What does this decision mean for NASA?
NASA awarded contracts to both Boeing and SpaceX in 2014 to provide crew transport vehicles to the International Space Station via the Commercial Crew Program. At the start of the program, most bets were on Boeing to take the lead, because of its extensive aerospace experience.
However, SpaceX moved very quickly with its new rocket, the Falcon 9, and its cargo ship, Dragon. While they suffered some early failures during testing, they aggressively built, tested and learned from each failure. In 2020, SpaceX successfully launched its first test crew to the International Space Station.
Meanwhile, Boeing struggled through some development setbacks. The outcome of this first test flight is a huge disappointment for Boeing and NASA. But NASA leadership has expressed its support for Boeing, and many experts, including me, believe it remains in the agency’s best interest to have more than one American crew launch system to support continued human space operations.
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NASA is also continuing its exchange partnership with Russia. This partnership provides the agency with multiple ways to get crew members to and from the space station.
As space station operations continue, NASA and its partners have enough options to get people to and from the station that they’ll always have the essential crew on the station โ even if there are launch disruptions for any one of the capable crewed vehicles. Having Starliner as an option will help with that redundancy.
What does this decision mean for Boeing?
I do think Boeing’s reputation is going to ultimately suffer. The company is going head-to-head with SpaceX. Now, the SpaceX Dragon crew spacecraft has several flights under its belt. It has proven a reliable way to get to and from the space station.
It’s important to remember that this was a test flight for Starliner. Of course, the program managers want each test flight to run perfectly, but you can’t anticipate every potential problem through ground testing. Unsurprisingly, some problems cropped up โ you expect them in a test flight.
The space environment is unforgiving. A small problem can become catastrophic in zero gravity. It’s hard to replicate these situations on the ground.
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The technology SpaceX and Boeing use is also radically different from the kind of capsule technology used in the early days of the Mercury, Gemini and Apollo programs.
NASA has evolved and made strategic moves to advance its mission over the past two decades. The agency has leaned into its legacy of thinking outside the box. It was an innovative move to break from tradition and leverage commercial competitors to advance the program. NASA gave the companies a set of requirements and left it up to them to figure out how they would meet them.
What does this decision mean for Starliner’s crew?
I know Butch Wilmore and Suni Williams as rock-solid professionals, and I believe their first thoughts are about completing their mission safely. They are both highly experienced astronauts with previous long-duration space station experience. I’m sure they are taking this in stride.
Prior to joining NASA, Williams was a Naval aviator and Wilmore a combat veteran, so these two know how to face risk and accomplish their missions. This kind of unfavorable outcome is always a possibility in a test mission. I am sure they are leaning forward with a positive attitude and using their bonus time in space to advance science, technology and space exploration.
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Their families shoulder the bigger impact. They were prepared to welcome the crew home in less than two weeks and now must adjust to unexpectedly being apart for eight months.
Right now, NASA is dealing with a ripple effect, with more astronauts than expected on the space station. More people means more consumables โ like food and clothing โ required. The space station has supported a large crew for short periods in the past, but with nine crew members on board today, the systems have to work harder to purify recycled drinking water, generate oxygen and remove carbon dioxide from their atmosphere.
Wilmore and Williams are also consuming food, and they didn’t arrive with the clothes and other personal supplies they needed for an eight-month stay, so NASA has already started increasing those deliveries on cargo ships.
What does this decision mean for the future?
Human spaceflight is excruciatingly hard and relentlessly unforgiving. A million things must go right to have a successful mission. It’s impossible to fully understand the performance of systems in a microgravity environment until they’re tested in space.
After having no other U.S. options for over 30 years, three different human spacecraft programs are now underway. In addition to the SpaceX Crew Dragon and the Boeing Starliner, NASA’s Orion spacecraft for the Artemis II mission, is planned to fly four astronauts around the Moon in the next couple of years.
These programs have had setbacks and bumps along the way โ and there will be more โ but I haven’t been this excited about human spaceflight since I was an 11-year-old cheering for Apollo and dreaming about putting the first human footprints on Mars.