Scientists reveal advance in brain research once thought impossible
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Using a speck of mouse brain matter the size of a grain of sand, scientists have created the first precise, three-dimensional map of a mammal's brain.
The map details the form, function and activity of 84,000 neurons, branched structures that fire off messages down a long arm, called an axon, and then through more than 500 million synapses, as well as 200,000 brain cells. The tiny piece of tissue contained 3.4 miles (5.4 kilometers) of neuronal wiring — nearly one and a half times the length of New York City's Central Park.
The work is the culmination of almost a decade of research by 150 scientists at 22 institutions led by the Allen Institute for Brain Science, the Baylor College of Medicine and Princeton University.
'One byproduct of this whole project shows us just how incredibly beautiful the brain is,' said Dr. Forrest Collman, associate director of data and technology at the Allen Institute, in a video shared by the organization.
'Just looking at these neurons shows you their detail and scale in a way that makes you appreciate the brain with a sense of awe in the way that when you look up, you know, say, at a picture of a galaxy far, far away,' he added.
The astonishing map represents only 1/500 of the full volume of a mouse's brain yet the team ended up with 1.6 petabytes of data — a staggering amount equivalent to 22 years of nonstop HD video, which the project, known as The Machine Intelligence from Cortical Networks (MICrONS) program, has already made publicly available.
Researchers described the work in several papers published in the journal Nature on April 9.
To make the map, scientists at Baylor College of Medicine in Houston began by using specialized microscopes to record the brain activity in a 1-cubic-millimeter portion of tissue in a lab mouse's visual cortex — where the animal processes what it sees — over the course of a few days.
The researchers made sure the mouse was awake and visually stimulated during the imaging by having the animal run on a treadmill and watch 10-second scenes from various movies, including 'The Matrix' and 'Mad Max: Fury Road.' YouTube clips of extreme sports such as motocross, luge and BASE jumping were also part of the viewing rotation, according to a Princeton University news release.
Next, after euthanizing the mouse, researchers from the Allen Institute in Seattle took that same cubic millimeter of brain and sliced it into more than 28,000 layers, each 1/400 the width of a human hair, and took images of each slice along the way. They then reconstructed the images into a composite.
'That took us about 12 days and 12 nights with the team taking shifts around the clock; not because we were cutting it by hand, it's a machine that is automated,' said Dr. Nuno Maçarico da Costa, an associate investigator at the Allen Institute.
'We needed to be there to stop at any point in time if we thought we're going to lose more than a section in a row.' If that happened, da Costa said the experiment would have to start from scratch, adding that the whole process was very 'stressful.'
A team at Princeton University in New Jersey subsequently deployed machine learning and artificial intelligence tools to trace the contour of every neuron through the slices, coloring the neurons to illuminate them individually in a process called segmentation. The AI-generated information is validated or proofread by the scientists involved, a process that is still ongoing.
The work has culminated in a unified view of what scientists are calling the mouse brain 'connectome' that shows how specific parts of the mouse brain are organized and offers insight into how different cell types work together.
'The connectome is the beginning of the digital transformation of brain science,' said Dr. Sebastian Seung, Princeton University's Evnin Professor in Neuroscience and a professor of computer science.
'With a few keystrokes you can search for information and get the results in seconds. Some of that information would have taken a whole Ph.D. thesis to get before. And that's the power of digital transformation,' he said in a news release.
Mapping the brain in this way had long been thought an impossible challenge. Molecular biologist Francis Crick, who won the Nobel prize for describing the structure of DNA, suggested neuroscientists would never be able to achieve such a detailed understanding of the brain.
'It is no use asking for the impossible, such as, say, the exact wiring diagram for a cubic millimeter of brain tissue and the way all its neurons are firing,' he wrote in Scientific American in 1979.
The mouse brain 'connectome' builds on similar work on even smaller creatures: The connectome of the nematode worm C. elegans was completed in 2019, and scientists revealed a map of all the fruit fly brain neurons in 2024.
One cubic millimeter of mouse brain is about 20 times bigger than the complete fruit fly brain, and much more complex, the researchers said. Nonetheless, the goal is to be able to map the entire mice brain connectome in the near future.
'I think right now the answer is no, it is not feasible, but I think everyone has really clear ideas about how they could break through those barriers. We're hoping in three or four years, we can say, yes, it is possible,' Collman told CNN.
However, he said mapping the human brain connectome in similar synaptic resolution would be a dramatically more difficult endeavor. 'The human brain is another factor of 1,500 or so larger than a mouse brain, and so that brings a whole host … of technical and ethical barriers to doing that,' he said.
However, it might be possible to trace axons throughout the human brain, if not synaptic connections, added Dr. Clay Reid, a senior investigator in brain science at the Allen Institute.
'The prospect of reconstructing the entire human brain at the level of all of the connections, that's something for the distant future.'
The neocortex is particularly interesting to study, because this region of the brain is what distinguishes mammal brains from those of other vertebrates, said Dr. Mariela Petkova, a research associate, and Dr. Gregor Schuhknecht, a postdoctoral fellow, both in the department of molecular and cellular biology at Harvard University. Petkova and Schuhknecht weren't involved in the creation of the mouse brain map.
'The researchers focused on this region because it is generally considered to be the seat of higher cognition and plays a key part in sensory perception, language processing, planning and decision-making,' they wrote in an article published alongside the research.
'Remarkably, these seemingly different functions are made possible by a blueprint that can be found, with some modifications, in all cortical areas and in all mammals.'
Lab mice are already widely used to understand human diseases, and a better comprehension of the mouse brain's form and function will present new possibilities for studying human brain disorders such as Alzheimer's, Parkinson's, autism and schizophrenia that involve disruptions in neural communication.
'If you have a broken radio and you have the circuit diagram, you'll be in a better position to fix it,' da Costa said in a news release. 'We are describing a kind of Google map or blueprint of this grain of sand. In the future, we can use this to compare the brain wiring in a healthy mouse to the brain wiring in a model of disease.'
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Some Dead Sea Scrolls may be even older than archaeologists thought, new study finds
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'The Dead Sea Scrolls were extremely important when they were discovered, because they completely changed the way we think about ancient Judaism and early Christianity,' said Popović, who is also dean of the Faculty of Religion, Culture and Society at the University of Groningen in the Netherlands. 'Out of around 1,000 manuscripts, a bit more than 200 are what we call biblical Old Testament, and they are the oldest copies we have of the Hebrew Bible. They gave us a lot of information about what the text looked like back then.' The scrolls are like a time machine, according to Popović, because they let scholars see what people were reading, writing and thinking at the time. 'They are physical, tangible evidence of a period of history that is crucial — whether you're Christian, Jewish or don't believe at all, because the Bible is one of the most influential books in the history of the world, so the scrolls allow us to study it as a form of cultural evolution,' he said. Almost none of the Dead Sea Scrolls — which were written mostly in Hebrew on parchment and papyrus — have dates on them. Based primarily on paleography, the study and deciphering of ancient writing and manuscripts, scholars have believed the manuscripts range from the third century BC to the second century AD. 'But now, with our project, we have to date some manuscripts already to the end of the fourth century BCE,' he said, meaning that the earliest scrolls could be up to 100 years older than previously thought. 'That's really exciting because it opens up new possibilities to think about how these texts were written and how they moved to other users and readers — outside of their original authors and their social circles,' Popović added. The findings will not only inspire further studies and affect historical reconstructions, according to the authors of the report, but will also unlock new prospects in the analysis of historical manuscripts. Earlier estimates of the manuscripts' age came from radiocarbon dating conducted in the 1990s. Chemist Willard Libby developed this method — used to ascertain the age of organic materials — in the late 1940s at the University of Chicago. Also known as carbon 14 dating, a chemical analysis of a sample, such as a fossil or manuscript, determines the quantity of carbon 14 atoms it contains. All living organisms absorb this element, but it starts to decay as soon as death occurs, so looking at how much is left can give a fairly accurate age of an organic specimen as old as about 60,000 years. Carbon dating has downsides, however. The analyzed sample is destroyed during the process, and some results can be misleading. 'The problem with earlier tests (on the scrolls) is that they didn't address the issue of castor oil,' Popović said. 'Castor oil is a modern invention, and it was used in the 1950s by the original scholars to make the text more legible. 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The scientists rated the results as 'realistic' or 'unrealistic,' based on their own paleographic experience, and found that Enoch had given realistic results on 79% of the samples. Some of the manuscripts in the study were found to be 50 to 100 years older than formerly thought, Popović said. One sample from a scroll known to contain verse from the Book of Daniel was once believed to date to the second century BC. 'That was a generation after the original author,' Popović said, 'and now with the carbon 14, we securely move it (further back) to the time of the author.' Another manuscript, with verses from the Book of Ecclesiastes, also dates older, Popović added. 'The manuscript was previously dated on paleographic grounds to 175 to 125 BCE, but now Enoch suggests 300 to 240 BCE,' he said. Eventually, artificial intelligence could supplant carbon 14 as a method of dating manuscripts, Popović suggested. 'Carbon 14 is destructive,' he said, 'because you need to cut off a little piece of the Dead Sea Scroll, and then it's gone. It's only 7 milligrams, but it's still stuff that you lose. With Enoch, you don't have to do any of this. This a first step. There are all sorts of possibilities to improve Enoch further.' If the team pushes forward with Enoch's development, Popović believes it could be used to assess scripts such as Syriac, Arabic, Greek and Latin. Scholars who were not involved with the study were encouraged by the findings. Having both AI and an enhanced carbon 14 dating method allows a level of calibration across both methodologies that is helpful, according to Charlotte Hempel, a professor of Hebrew Bible and Second Temple Judaism at the University of Birmingham in the United Kingdom. 'The pronounced pattern seems to be that AI offers a narrower window within the Carbon 14 window,' she said via email. 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A surprising study revealed biological activity on a distant planet. Weeks later, scientists say there's more to the story
Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. A tiny sign revealed in April seemed like it might change the universe as we know it. Astronomers had detected just a hint, a glimmer of two molecules swirling in the atmosphere of a distant planet called K2-18b — molecules that on Earth are produced only by living things. It was a tantalizing prospect: the most promising evidence yet of an extraterrestrial biosignature, or traces of life linked to biological activity. But only weeks later, new findings suggest the search must continue. 'It was exciting, but it immediately raised several red flags because that claim of a potential biosignature would be historic, but also the significance or the strength of the statistical evidence seemed to be too high for the data,' said Dr. Luis Welbanks, a postdoctoral research scholar at Arizona State University's School of Earth and Space Exploration. While the molecules identified on K2-18b by the April study — dimethyl sulfide, or DMS, and dimethyl disulfide, or DMDS — are associated largely with microbial organisms on our planet, scientists point out that the compounds can also form without the presence of life. Now, three teams of astronomers not involved with the research, including Welbanks, have assessed the models and data used in the original biosignature discovery and got very different results, which they have submitted for peer review. Meanwhile, the lead author of the April study, Nikku Madhusudhan, and his colleagues have conducted additional research that they say reinforces their previous finding about the planet. And it's likely that additional observations and research from multiple groups of scientists are on the horizon. The succession of research papers revolving around K2-18b offers a glimpse of the scientific process unfolding in real time. It's a window into the complexities and nuances of how researchers search for evidence of life beyond Earth — and shows why the burden of proof is so high and difficult to reach. Located 124 light-years from Earth, K2-18b is generally considered a worthy target to scour for signs of life. It is thought to be a Hycean world, a planet entirely covered in liquid water with a hydrogen-rich atmosphere, according to previous research led by Madhusudhan, a professor of astrophysics and exoplanetary science at the University of Cambridge's Institute of Astronomy. And as such, K2-18b has rapidly attracted attention as a potentially habitable place beyond our solar system. Convinced of K2-18b's promise, Madhusudhan and his Cambridge colleagues used observations of the planet by the largest space telescope in operation, the James Webb Space Telescope, to study the planet further. But two scientists at the University of Chicago — Dr. Rafael Luque, a postdoctoral scholar in the university's department of astronomy and astrophysics, and Michael Zhang, a 51 Pegasi b / Burbidge postdoctoral fellow — spotted some problems with what they found. After reviewing Madhusudhan and his team's April paper, which followed up on their 2023 research, Luque and Zhang noticed that the Webb data looked 'noisy,' Luque said. Noise, caused by imperfections in the telescope and the rate at which different particles of light reach the telescope, is just one challenge astronomers face when they study distant exoplanets. Noise can distort observations and introduce uncertainties into the data, Zhang said. Trying to detect specific gases in distant exoplanet atmospheres introduces even more uncertainty. The most noticeable features from a gas like dimethyl sulfide stem from a bond of hydrogen and carbon molecules — a connection that can stretch and bend and absorb light at different wavelengths, making it hard to definitively detect one kind of molecule, Zhang said. 'The problem is basically every organic molecule has a carbon-hydrogen bond,' Zhang said. 'There's hundreds of millions of those molecules, and so these features are not unique. If you have perfect data, you can probably distinguish between different molecules. But if you don't have perfect data, a lot of molecules, especially organic molecules, look very similar, especially in the near-infrared.' Delving further into the paper, Luque and Zhang also noticed that the perceived temperature of the planet appeared to increase sharply from a range of about 250 Kelvin to 300 Kelvin (-9.67 F to 80.33 F or -23.15 C to 26.85 C) in research Madhusudhan published in 2023 to 422 Kelvin (299.93 F or 148.85 C) in the April study. Such harsh temperatures could change the way astronomers think about the planet's potential habitability, Zhang said, especially because cooler temperatures persist in the top of the atmosphere — the area that Webb can detect — and the surface or ocean below would likely have even higher temperatures. 'This is just an inference only from the atmosphere, but it would certainly affect how we think about the planet in general,' Luque said. Part of the issue, he said, is that the April analysis didn't include data collected from all three Webb instruments Madhusudhan's team used over the past few years. So Luque, Zhang and their colleagues conducted a study combining all the available data to see whether they could achieve the same results, or even find a higher amount of dimethyl sulfide. They found 'insufficient evidence' of both molecules in the planet's atmosphere. Instead, Luque and Zhang's team spotted other molecules, like ethane, that could fit the same profile. But ethane does not signify life. Arizona State's Welbanks and his colleagues, including Dr. Matt Nixon, a postdoctoral researcher in the department of astronomy at the University of Maryland College Park, also found what they consider a fundamental problem with the April paper on K2-18b. The concern, Welbanks said, was with how Madhusudhan and his team created models to show which molecules might be in the planet's atmosphere. 'Each (molecule) is tested one at a time against the same minimal baseline, meaning every single model has an artificial advantage: It is the only explanation permitted,' Welbanks said. When Welbanks and his team conducted their own analysis, they expanded the model from Madhusudhan's study. '(Madhusudhan and his colleagues) didn't allow for any other chemical species that could potentially be producing these small signals or observations,' Nixon said. 'So the main thing we wanted to do was assess whether other chemical species could provide an adequate fit to the data.' When the model was expanded, the evidence for dimethyl sulfide or dimethyl disulfide 'just disappears,' Welbanks said. Madhusudhan believes the studies that have come out after his April paper are 'very encouraging' and 'enabling a healthy discussion on the interpretation of our data on K2-18b.' He reviewed Luque and Zhang's work and agreed that their findings don't show a 'strong detection for DMS or DMDS.' When Madhusudhan's team published the paper in April, he said the observations reached the three-sigma level of significance, or a 0.3% probability that the detections occurred by chance. For a scientific discovery that is highly unlikely to have occurred by chance, the observations must meet a five-sigma threshold, or below a 0.00006% probability that the observations occurred by chance. Meeting such a threshold will require many steps, Welbanks said, including repeated detections of the same molecule using multiple telescopes and ruling out potential nonbiological sources. While such evidence could be found in our lifetime, it is less likely to be a eureka moment and more a slow build requiring a consensus among astronomers, physicists, biologists and chemists. 'We have never reached that level of evidence in any of our studies,' Madhusudhan wrote in an email. 'We have only found evidence at or below 3-sigma in our two previous studies (Madhusudhan et al. 2023 and 2025). We refer to this as moderate evidence or hints but not a strong detection. I agree with (Luque and Zhang's) claim which is consistent with our study and we have discussed the need for stronger evidence extensively in our study and communications.' In response to the research conducted by Welbanks' team, Madhusudhan and his Cambridge colleagues have authored another manuscript expanding the search on K2-18b to include 650 types of molecules. They have submitted the new analysis for peer review. 'This is the largest search for chemical signatures in an exoplanet to date, using all the available data for K2-18b and searching through 650 molecules,' Madhusudhan said. 'We find that DMS continues to be a promising candidate molecule in this planet, though more observations are required for a firm detection as we have noted in our previous studies.' Welbanks and Nixon were pleased that Madhusudhan and his colleagues addressed the concerns raised but feel that the new paper effectively walks back central claims made in the original April study, Welbanks said. 'The new paper tacitly concedes that the DMS/DMDS detection was not robust, yet still relies on the same flawed statistical framework and a selective reading of its own results,' Welbanks said in an email. 'While the tone is more cautious (sometimes), the methodology continues to obscure the true level of uncertainty. The statistical significance claimed in earlier work was the product of arbitrary modeling decisions that are not acknowledged.' Luque said the Cambridge team's new paper is a step in the right direction because it explores other possible chemical biosignatures. 'But I think it fell short in the scope,' Luque said. 'I think it restricted itself too much into being a rebuttal to the (Welbanks) paper.' Separately, however, the astronomers studying K2-18b agree that pushing forward on researching the exoplanet contributes to the scientific process. 'I think it's just a good, healthy scientific discourse to talk about what is going on with this planet,' Welbanks said. 'Regardless of what any single author group says right now, we don't have a silver bullet. But that is exactly why this is exciting, because we know that we're the closest we have ever been (to finding a biosignature), and I think we may get it within our lifetime, but right now, we're not there. That is not a failure. We're testing bold ideas.'
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How one planet is revealing why it's so hard to detect life beyond Earth
Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. A tiny sign revealed in April seemed like it might change the universe as we know it. Astronomers had detected just a hint, a glimmer of two molecules swirling in the atmosphere of a distant planet called K2-18b — molecules that on Earth are produced only by living things. It was a tantalizing prospect: the most promising evidence yet of an extraterrestrial biosignature, or traces of life linked to biological activity. But only weeks later, new findings suggest the search must continue. 'It was exciting, but it immediately raised several red flags because that claim of a potential biosignature would be historic, but also the significance or the strength of the statistical evidence seemed to be too high for the data,' said Dr. Luis Welbanks, a postdoctoral research scholar at Arizona State University's School of Earth and Space Exploration. While the molecules identified on K2-18b by the April study — dimethyl sulfide, or DMS, and dimethyl disulfide, or DMDS — are associated largely with microbial organisms on our planet, scientists point out that the compounds can also form without the presence of life. Now, three teams of astronomers not involved with the research, including Welbanks, have assessed the models and data used in the original biosignature discovery and got very different results, which they have submitted for peer review. Meanwhile, the lead author of the April study, Nikku Madhusudhan, and his colleagues have conducted additional research that they say reinforces their previous finding about the planet. And it's likely that additional observations and research from multiple groups of scientists are on the horizon. The succession of research papers revolving around K2-18b offers a glimpse of the scientific process unfolding in real time. It's a window into the complexities and nuances of how researchers search for evidence of life beyond Earth — and shows why the burden of proof is so high and difficult to reach. Located 124 light-years from Earth, K2-18b is generally considered a worthy target to scour for signs of life. It is thought to be a Hycean world, a planet entirely covered in liquid water with a hydrogen-rich atmosphere, according to previous research led by Madhusudhan, a professor of astrophysics and exoplanetary science at the University of Cambridge's Institute of Astronomy. And as such, K2-18b has rapidly attracted attention as a potentially habitable place beyond our solar system. Convinced of K2-18b's promise, Madhusudhan and his Cambridge colleagues used observations of the planet by the largest space telescope in operation, the James Webb Space Telescope, to study the planet further. But two scientists at the University of Chicago — Dr. Rafael Luque, a postdoctoral scholar in the university's department of astronomy and astrophysics, and Michael Zhang, a 51 Pegasi b / Burbidge postdoctoral fellow — spotted some problems with what they found. After reviewing Madhusudhan and his team's April paper, which followed up on their 2023 research, Luque and Zhang noticed that the Webb data looked 'noisy,' Luque said. Noise, caused by imperfections in the telescope and the rate at which different particles of light reach the telescope, is just one challenge astronomers face when they study distant exoplanets. Noise can distort observations and introduce uncertainties into the data, Zhang said. Trying to detect specific gases in distant exoplanet atmospheres introduces even more uncertainty. The most noticeable features from a gas like dimethyl sulfide stem from a bond of hydrogen and carbon molecules — a connection that can stretch and bend and absorb light at different wavelengths, making it hard to definitively detect one kind of molecule, Zhang said. 'The problem is basically every organic molecule has a carbon-hydrogen bond,' Zhang said. 'There's hundreds of millions of those molecules, and so these features are not unique. If you have perfect data, you can probably distinguish between different molecules. But if you don't have perfect data, a lot of molecules, especially organic molecules, look very similar, especially in the near-infrared.' Delving further into the paper, Luque and Zhang also noticed that the perceived temperature of the planet appeared to increase sharply from a range of about 250 Kelvin to 300 Kelvin (-9.67 F to 80.33 F or -23.15 C to 26.85 C) in research Madhusudhan published in 2023 to 422 Kelvin (299.93 F or 148.85 C) in the April study. Such harsh temperatures could change the way astronomers think about the planet's potential habitability, Zhang said, especially because cooler temperatures persist in the top of the atmosphere — the area that Webb can detect — and the surface or ocean below would likely have even higher temperatures. 'This is just an inference only from the atmosphere, but it would certainly affect how we think about the planet in general,' Luque said. Part of the issue, he said, is that the April analysis didn't include data collected from all three Webb instruments Madhusudhan's team used over the past few years. So Luque, Zhang and their colleagues conducted a study combining all the available data to see whether they could achieve the same results, or even find a higher amount of dimethyl sulfide. They found 'insufficient evidence' of both molecules in the planet's atmosphere. Instead, Luque and Zhang's team spotted other molecules, like ethane, that could fit the same profile. But ethane does not signify life. Arizona State's Welbanks and his colleagues, including Dr. Matt Nixon, a postdoctoral researcher in the department of astronomy at the University of Maryland College Park, also found what they consider a fundamental problem with the April paper on K2-18b. The concern, Welbanks said, was with how Madhusudhan and his team created models to show which molecules might be in the planet's atmosphere. 'Each (molecule) is tested one at a time against the same minimal baseline, meaning every single model has an artificial advantage: It is the only explanation permitted,' Welbanks said. When Welbanks and his team conducted their own analysis, they expanded the model from Madhusudhan's study. '(Madhusudhan and his colleagues) didn't allow for any other chemical species that could potentially be producing these small signals or observations,' Nixon said. 'So the main thing we wanted to do was assess whether other chemical species could provide an adequate fit to the data.' When the model was expanded, the evidence for dimethyl sulfide or dimethyl disulfide 'just disappears,' Welbanks said. Madhusudhan believes the studies that have come out after his April paper are 'very encouraging' and 'enabling a healthy discussion on the interpretation of our data on K2-18b.' He reviewed Luque and Zhang's work and agreed that their findings don't show a 'strong detection for DMS or DMDS.' When Madhusudhan's team published the paper in April, he said the observations reached the three-sigma level of significance, or a 0.3% probability that the detections occurred by chance. For a scientific discovery that is highly unlikely to have occurred by chance, the observations must meet a five-sigma threshold, or below a 0.00006% probability that the observations occurred by chance. Meeting such a threshold will require many steps, Welbanks said, including repeated detections of the same molecule using multiple telescopes and ruling out potential nonbiological sources. While such evidence could be found in our lifetime, it is less likely to be a eureka moment and more a slow build requiring a consensus among astronomers, physicists, biologists and chemists. 'We have never reached that level of evidence in any of our studies,' Madhusudhan wrote in an email. 'We have only found evidence at or below 3-sigma in our two previous studies (Madhusudhan et al. 2023 and 2025). We refer to this as moderate evidence or hints but not a strong detection. I agree with (Luque and Zhang's) claim which is consistent with our study and we have discussed the need for stronger evidence extensively in our study and communications.' In response to the research conducted by Welbanks' team, Madhusudhan and his Cambridge colleagues have authored another manuscript expanding the search on K2-18b to include 650 types of molecules. They have submitted the new analysis for peer review. 'This is the largest search for chemical signatures in an exoplanet to date, using all the available data for K2-18b and searching through 650 molecules,' Madhusudhan said. 'We find that DMS continues to be a promising candidate molecule in this planet, though more observations are required for a firm detection as we have noted in our previous studies.' Welbanks and Nixon were pleased that Madhusudhan and his colleagues addressed the concerns raised but feel that the new paper effectively walks back central claims made in the original April study, Welbanks said. 'The new paper tacitly concedes that the DMS/DMDS detection was not robust, yet still relies on the same flawed statistical framework and a selective reading of its own results,' Welbanks said in an email. 'While the tone is more cautious (sometimes), the methodology continues to obscure the true level of uncertainty. The statistical significance claimed in earlier work was the product of arbitrary modeling decisions that are not acknowledged.' Luque said the Cambridge team's new paper is a step in the right direction because it explores other possible chemical biosignatures. 'But I think it fell short in the scope,' Luque said. 'I think it restricted itself too much into being a rebuttal to the (Welbanks) paper.' Separately, however, the astronomers studying K2-18b agree that pushing forward on researching the exoplanet contributes to the scientific process. 'I think it's just a good, healthy scientific discourse to talk about what is going on with this planet,' Welbanks said. 'Regardless of what any single author group says right now, we don't have a silver bullet. But that is exactly why this is exciting, because we know that we're the closest we have ever been (to finding a biosignature), and I think we may get it within our lifetime, but right now, we're not there. That is not a failure. We're testing bold ideas.'
