Early Brain Scans Could Predict Likelihood of Autism Diagnosis

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 Doctors typically diagnose Autism Spectrum Disorder (ASD) at around age four by evaluating behaviors that start to develop at age two. But infants at high risk of autism can now get a brain scan to accurately predict the likelihood of diagnosis, according to
 <a href="http://stm.sciencemag.org/content/9/393/eaag2882">
 a new study
 </a>
 .
 

 Researchers from the University of North Carolina at Chapel Hill examined functioning magnetic resonance imaging (fMRI) brain scans and behavioral tendencies of 59 six-month-olds who had older siblings on the autism spectrum.
 

 They collected similar information when the children were two, then fed all of this material into a machine-learning algorithm that looked for correlations between the scanned data and behavioral data. The computer used the brain scans to predict whether the child would later be diagnosed with autism. It caught 9 of the 11 cases and produced no false positives (a result that indicates that a condition is present when, in fact, it is not).
 
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/autism-brain-scans.width-990_IRJFjar.jpg"/>
<figcaption>Schematics representing brain scan signatures that predicted later autism diagnosis in infants.
 
 </figcaption>
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 However, there is still a dilemma of whether
 <a href="http://www.pbs.org/wgbh/nova/next/body/autism-early-intervention/">
 early behavioral intervention
 </a>
 for those diagnosed with ASD is ethical. Here’s Anil Ananthaswamy,
 <a href="https://www.newscientist.com/article/2133941-baby-brain-scans-can-predict-who-is-likely-to-develop-autism/">
 reporting
 </a>
 for New Scientist:
 
<blockquote>

 Many people consider autism to be a fundamental part of their personality, and although some autistic people have substantial difficulty communicating or forming relationships, some people with autism value traits such as abilities to concentrate, pay attention to detail or see things from a novel perspective.
 
</blockquote>

 Behavioral therapy might be less controversial if future research were to link brain functioning to specific behaviors. This would allow for treatment targeted at detrimental behaviors and in general would improve the treatment’s efficacy. Further research, beyond replicating the original results, will need to include infants at low risk of developing autism, allowing doctors to use the test on any infant—not just those with autistic siblings.
 

 Other desired improvements include lowering the cost of diagnostic tests. Here’s Nicholette Zeliadt,
 <a href="https://www.scientificamerican.com/article/brain-scans-may-forecast-autism-in-babies/">
 reporting
 </a>
 for Scientific American:
 
<blockquote>

 The type of brain scan the researchers used costs several thousand dollars, but more noninvasive and affordable methods, such as electroencephalography or near-infrared spectroscopy, might one day be used in clinics.
 
</blockquote>

 For decades, scientists have been looking for early signs of neural or behavioral developments associated with autism. An earlier diagnosis would allow doctors to educate parents and begin behavioral therapy before symptoms manifest.
 
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 Photo credit: R.W. Emerson et al., Science Translational Medicine (2017)

Ancient Comets May Have Delivered Xenon To Earth

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 Comets hurtling through space 3.5–4.5 billion years ago may have deposited heavy isotopes of xenon into Earth’s atmosphere. This clue to the isotopes’ mysterious origins suggests that comets visited Earth in its earliest days, that the moon and atmosphere are younger than we originally thought, and that comets might have delivered the first organic material to our fledgeling planet.
 

 While there are only trace amounts of xenon in the atmosphere, the noble gas doesn’t chemically react with other elements, meaning it’s
 <a href="http://www.spacedaily.com/reports/Rosetta_finds_comet_connection_to_Earths_atmosphere_999.html">
 a relatively stable marker
 </a>
 whose origin is easy to trace.
 
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/crescent_comet_67p.width-990_sV88K8o.jpg"/>
<figcaption>Comet 67P/Churyumov-Gerasimenko
 
 </figcaption>
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 But the presence of a surprisingly high percentage of heavy xenon isotopes in Earth’s atmosphere has hampered our understanding of our planet’s origins. Scientists previously couldn’t find any plausible sources for these heavier isotopes—solar wind and meteors, for example, only contain lighter isotopes.
 

 The new data comes from gas collected during the
 <a href="http://sci.esa.int/rosetta/">
 Rosetta mission
 </a>
 , which flew a spacecraft near the surface of 67P/Churyumov-Gerasimenko, a member of the family of comets controlled by Jupiter’s gravity. The samples contained a mixture of three noble gases, krypton, argon, and xenon. This comet’s xenon contained the same perplexing heavy isotopes, suggesting that Earth may have received a fraction of its xenon from comets. The model that best fits the atmosphere’s xenon makeup estimates that about 22% of it came from comets.
 

 These
 <a href="http://science.sciencemag.org/content/356/6342/1069">
 new findings
 </a>
 allow scientist to correct small errors in dating the planet’s evolution. Here’s Leah Crane for
 <a href="https://www.newscientist.com/article/2134120-the-mystery-xenon-in-earths-atmosphere-came-from-icy-comets/">
 New Scientist
 </a>
 :
 
<blockquote>

 On Earth, we presumed the presence of this isotope was primarily a result of decaying iodine. We know the rate at which iodine decays, so we use the quantity of xenon-129 to gauge the time at which planetary events took place. But if 22 per cent of the xenon in Earth’s atmosphere was transported by comets, models based on iodine decay aren’t accurate. They overestimate the age of Earth’s atmosphere and the moon.
 
</blockquote>

 Since this study only examines data from one comet, missions to other comets will need to verify the results. But this cometary xenon further links Earth’s birth with the rest of the solar system. Results from other comets will provide further details of Earth’s formative years and perhaps even an explanation for how the first organic molecules arrived on Earth.
 
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 Image Credit: Giuseppe Conzo/ESA/Rosetta/NAVCAM

Air pollution is an issue around the world, though its effects are not evenly distributed.

Too Much Pollution for One Place

Emissions from waste treatment facilities and power plants contribute to a slow-motion public health disaster in Chester, PA.

New Fossils Push Back Earliest Single-Celled Skeletons 200 Million Years

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 Imagine trying to eat food without teeth, or walk without a backbone.


 While the single-celled organisms that dominated early Earth’s oceans didn’t have much need for teeth, they did find some evolutionary advantage in making their own minerals. According to research published last week, life has been making its own hard parts for at least 810 million years, about 200 million years longer than previously thought. It’s the first occurrence of what scientists call biomineralization, and it could give us deeper insight into both the evolution of living things and Earth’s early climate.


 Previously, scientists hadn’t found evidence of organisms making their own skeletons before the rapid diversification of life around 490-550 million years ago known as the Cambrian explosion. But in the mid-2000s, Phoebe Cohen, a Williams College paleontologist and lead author of the recent study, re-examined fossil evidence that would end up setting the date back much further.


 Cohen was in the Yukon studying microfossils from a 200-foot-thick section of lime, mudstone, and slate, and she suspected that they could have been formed by biological processes. These microfossils were originally discovered in the 1980s, when they were dated to the Neoproterozoic Era, about 250 million years prior to the Cambrian explosion. But scientists at the time were unable to determine the exact age of the fossils, nor were they able to discern whether they were crafted by geology or life itself.

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 To unlock the minerals’ secrets, Cohen and her co-author Nicholas Tosca borrowed a method of microscopic imaging from materials scientists that uses electrons instead of light. That imaging revealed highly organized, long, and slender crystals that were oriented and spaced in such a way that they could only have been made biologically, Cohen said.


 The minerals possibly served as an armor-like casing constructed by now-extinct organisms, though Cohen and her team did not find conclusive evidence of their function, nor did they find remnants of the cells themselves, which rarely preserve for so long. Cohen said these parts could have been a defense against a predation, since some single-celled organisms today use hard parts for protection. Plus, evidence in the fossil record suggests that predatory single-celled organisms would have existed at the same time as Cohen’s fossils.


 Shuhai Xiao, a paleobiologist at Virginia Tech who did not contribute to the paper, said it’s a reasonable hypothesis. “Organisms don’t make something just because there is material available,” Xiao said. “There must also be an ecological need.”


 Cohen and Tosca’s research cleverly uses “the way a mineral is constructed” to determine its origin, said Sara Pruss, a Smith College geologist who did not contribute to this study. It’s the first study to use a detailed analysis of crystal structure to find evidence of biomineralization. The same technique could be used to find other biomineralization from the same era in other parts of the world.


 The analysis also revealed that the minerals were composed of a particular flavor of phosphorus called hydroxylapatite, which is rarely found in oceanic single-celled organisms today. Cohen and her team found evidence in the rocks suggesting that the oceans at the time contained less oxygen than today. This provided a suitable environment for elevated phosphorus concentrations, which may have helped spur its use in biomineralization.


 “Hydroxylapatite is not very stable, so the preservation of the mineral in rocks of this age is remarkable,” Xiao said.


 The team was able to constrain the age of the fossils to an unusually narrow time-frame – 810 million years ago, give or take about 6 million years. As a result, Cohen thinks she’ll be able to find more fossils because she will only have to search a much narrower slice of the fossil record than before. “I was looking through a hundred million years of time before, and now I’m looking through ten million years,” she said.


 The new study leaves a few questions unanswered, and poses a few new ones of its own. For one, biomineralization has evolved several different times. This study illustrates how one branch of life gained the ability to make skeletal parts, but there are still several others to puzzle out. And then it blasts open a period of more than 200 million years in which scientists so far have found no evidence of biomineralization, a range of time that Cohen points out is as wide as that between the present day and the dawn of the dinosaurs.


 “We’re seeing a little bit of a mystery there,” Cohen said of the gap. They will now try to pinpoint when the shift from using phosphorus to using carbon occurred and find out what, if anything, organisms were making during that time. “That’s the big open question,” Cohen said.

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 Photo credit: Phoebe A. Cohen

These 810 million-year-old fossils suggest early marine life protected itself by making skeletons from phosphorus.

Earth’s Microbial Life May Have Been Able To Survive On Mars

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 Over the past few years, the
 
 Curiosity
 
 rover has dug up clues suggesting that Mars’s Gale Crater once hosted a liquid-water lake.
 

 Now, a new report says that the lake may have been long-lasting and chemically diverse—two qualities that suggest, if the lake were on Earth, that it would have supported a rich diversity of microbial life.
 
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<img alt="Curiosity Self Portrait" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/curiosity-self-portrait-1.width-990_S7qUi4M.jpg"/>
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 In a paper published in
 
 Science
 
 last week, Joel Hurowitz of Stony Brook University describes an ancient lake that was chemically divided, with oxygen-poor water in deeper parts of the lake and oxygen-rich water closer to the surface. Different microbes thrive at different oxygen concentrations, meaning each layer of the lake would have been capable of supporting a different form of microbial life.
 

 The analysis of the crater’s layers of sediment and chemical contents also suggest the planet would have been warm enough during the period spanning 3.1 to 3.8 billion years ago to support an aquatic lake more or less continuously. The rover has now traveled more than 100 meters vertically up the lake bed,  allowing the team to say with more certainty that the lake was sustained for a long period of time.
 

 Since the scientists are studying rocks that are billions of years old on a planet a hundred million miles away, it can be difficult to detect the subtle signatures left by the lake. “I think [Hurowitz’s] seminal contribution is the chemistry,” said Raymond Arvidson, a scientist on the
 
 Curiosity
 
 mission who did not contribute to the new paper.
 

 The precise data from the rover allowed the mission team to understand “the detailed and very nuanced changes in chemistry within the lake and changes in the environment over time,” said Ashwin Vasavada, a project scientist at NASA’s Jet Propulsion lab and a co-author of the paper. “I’m impressed with the level of detail that our [scientific equipment] was able to extract from these rocks,” he said.
 

 The rover landed in Gale Crater in 2012 with the aim of determining whether the planet had ever been habitable to life found on Earth.
 
 Curiosity
 
 landed at the foot of  a five-kilometer tall mountain containing tens of millions of years of climate data locked in its layers of sediment—an ideal window into Mars’ climatic history. In 2014 and 2015, John Grotzinger of Caltech used data from
 
 Curiosity
 
 to argue that Gale Crater contained a liquid-water lake at some point between 3.1 and 3.8 billion years ago. He also characterized the physical makeup of the crater, determining, among other things, the ages of the layers. Hurowitz developed his theory by matching the chemical data to Grotzinger’s physical model.
 

 These new findings suggest that Mars once supported a range of chemical environments that may have shared more in common with present-day Earth than scientists previously believed. “The more we look at Mars the more complicated it becomes and the more interesting it becomes,” Arvidson said. “And the more it looks like portions of the lake were habitable 3.18 to 3.8 billion years ago.”
 
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 Image credit: NASA

Protecting A Little More Land Could Save A Lot More Biodiversity

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 Save the Amazon rainforests. Save the whales. Save the giant pandas.


 The conservation movement has historically focused on protecting a specific species or its habitat, but there are a lot of species and habitats to save—far too many to make slogans for them all. As humanity’s footprint continues to expand, the list continues to grow, spurring scientists to find a more sophisticated—though less glamorous — way to protect biodiversity. According to a new study, we may only need to protect a little more land to preserve a significantly greater amount of biodiversity.

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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/33980901271_fb4cb86b57_o.width-990_6IjenEG.jpg"/>
<figcaption>An African elephant and its offspring.
 
 </figcaption>
</figure>

 The paper by Laura Pollock, Wilfried Thuiller, and Walter Jetz argues that strategies for more efficiently conserving biodiversity can pinpoint areas that could be significant contributors to global diversity–more specifically, that a 5% expansion of protected land could as much as triple the amount of protected biodiversity.


 In the past, conservation often meant rounding up endangered species and building a fence around them. But biologists know it’s not that simple.


 For one, there’s more than one type of biodiversity. For a long time, scientists primarily considered only the number of species in a protected area. But now studies like this latest one also consider phylogenetic diversity, or the degree to which the tree of life is well represented, as well as functional diversity, such as the variety of diets or body sizes, present in an ecosystem.


 Scientists also have to balance preserving high densities of biodiversity at the local level and wide ranges of biodiversity at a global level. It’s a matter of choosing between whether “we want to capture every little piece of biodiversity” or try to maximize biodiversity in certain areas, said Pollock, a postdoc at University of Grenoble in France.


 Pollock and her colleagues’ paper maps out which unprotected parts of the globe, if protected, would maximize each of these three facets of biodiversity—species, phylogenetic, and functional—for both mammals and birds. While other papers have looked at each of these aspects before, none have applied as broad a scope as Pollock’s. “What’s novel is the application to a global scale,” said Marc Cadotte, an associate professor researching conservation, ecology, and evolution at University of Toronto-Scarborough who did not contribute to this paper. “It’s nice to see this all coming together to a global view of conservation.”



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<h2>
 Conservation by Big Data
</h2>

 Such in-depth, large-scale analyses require a finely organized library of data and a wealth of processing power. Jetz said that this paper was six to eight years in the making—four to six years of organizing genetic data into a reasonable approximation of the tree of life, followed by two years of analyzing the data, including running algorithms that search for the most efficient ways to conserve biodiversity. “It’s computationally quite tricky to run these,” he said.


 Before, simpler analyses assumed that conserving the most diverse areas would protect the most biodiversity. When deciding whether to protect an area, biologists would only consider whether this or other areas contained more biodiversity. In their analysis, Pollock and her team didn’t assume that the most diverse areas are the most important. Instead, they checked all of the possible combinations of areas to see which protect the most biodiversity as a whole. It’s not unlike IBM’s computer Deep Blue’s strategy for defeating Grandmaster Garry Kasparov in chess, in which the computer assessed almost all possible moves for each of its turns.


 The benefit of these cumbersome analyses is that they do a much better job of conserving biodiversity than traditional methods, according to the study. Pollock and her team found that their algorithms expanded protected land by just 5% but included over 1,500 more bird species than simply prioritizing diverse areas. “We were able to much more efficiently—that is, over much less space and with much less resources—conserve more of the tree of life and functional diversity,” Jetz said.


 It’s not a universal solution, though. Local and global conservation require two very different strategies. The end goal “matters a lot in terms of which areas you would protect,” Pollock said.


 Her study also found that strategies for conserving phylogenetic and species diversity were more similar than strategies for saving functional diversity. In other words, if you’re trying to protect large chunks of the tree of life, you’ll probably succeed in conserving a lot of different species. But you might omit important functions in the ecosystem, perhaps cutting out a key link in the food chain, for example.


 Improving efficiency is a priority for conservation biologists because so much biodiversity is either poorly protected or not protected at all. According to the paper, 13% of the bird tree of life and 23% of the mammal tree of life are unprotected. Even in protected areas, diversity has suffered. Pollock said that around a quarter of all species worldwide are absent from any protected area, a fact she finds “alarming.” And even diversity currently well-contained could be lost in the future. There continue to be problems worldwide with underfunded and poorly managed conservation sites, Cadotte said, as well as sites ravaged by poachers, leaving species that are theoretically protected still vulnerable to extinction.


 Pollock and her colleagues intend to replicate and refine their methods. Future iterations of the study could use more data about each species’ role in the ecosystem, Jetz said, particularly for tropical species. They could also include a more detailed mammalian tree of life, as well as more finely grained spatial maps.



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 To him, improvements will come not from improved methods but from expanded data sets, saying that progress will “require good old-fashioned observations from the field.” Scientists only began collecting phylogenetic and functional data in the last 20 years, a relatively short time ago compared with other data. Pollock said that more work also needs to be done linking their methods to specific conservation goals, such as determining which approaches are better for global priorities than local priorities or which conserve a greater swath of the tree of life over ecosystem functions.


 The authors hope their approach will be useful both for policy makers and non-governmental organizations. Pollock sees the study not so much as rewriting the rulebook for conservation as simply shifting a perspective. “We need to start taking a broader look at these other metrics at the same time because we do not want to miss really important species,” she said.


<a href="https://mol.org/species/">
 Interactive maps
 </a>
 of global biodiversity distributions could help groups trying to shape public policy, Jetz said, pointing out that policy makers take notice when their country sticks out on conservation maps as a global priority.


 While the plans ultimately will be carried out by local governments and organizations, the global approach shouldn’t be forgotten, Pollock said. “Conservation is very narrowly focused…we very rarely look at a broader scale,” she said. “Taking a step back and keeping that larger perspective in mind when doing local conservation would be an ideal way forward.”


 Photo credits:
 <a href="https://www.flickr.com/photos/paulrin/33980901271/">
 fcmarriot/Flickr (CC BY-NC 2.0)
 </a>
 ,
 <a href="https://www.flickr.com/photos/craigoneal/3965742769/">
 Craig ONeal/Flickr (CC BY-NC 2.0)
 </a>

By applying algorithms to giant datasets traits, researchers found more efficient strategies for conserving biodiversity.

The Moon’s Interior Might Be Wet

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 Much of the moon’s interior may contain water, new research finds.
 

 Scientists from Brown University found evidence of water from satellite imaging of the remains of volcanic eruptions across the surface of the natural satellite. Since this material was expelled from below the moon’s surface, this suggests that the water came from the moon’s mantle. And nearly all the volcanic, or pyroclastic, deposits studied contained evidence of water, suggesting that the water is spread out across the planet’s whole interior and is relatively plentiful.
 
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/145983.width-990_kCIcYZa.png"/>
<figcaption>Evidence from ancient volcanic deposits suggests that lunar magma contained substantial amounts of water, bolstering the idea that the moon's interior is water-rich.
 
 </figcaption>
</figure>

 Here’s Space.com’s Samantha Mathewson talking to Ralph Milliken, the study’s lead author:
 
<blockquote>

 “Our work shows that nearly all of the large pyroclastic deposits also contain water, so this seems to be a common characteristic of magmas that come from the deep lunar interior,” Milliken said. “That is, most of the mantle of the moon may be ‘wet.’ ”
 
</blockquote>

 Scientists first began to suspect that the moon contained more than trace amounts of water back in 2011, when volcanic glass beads from the Apollo 15 and 17 missions were found to contain similar amounts of water to volcanic rock on Earth, suggesting that near the source of the Apollo samples, the moon’s interior contains as much water as Earth’s.
 

 But the possibility remained that these samples were anomalous, and that the rest of the moon’s interior contained very little water. The fact that Milliken’s team, which published the research yesterday in
 
 Nature Geosciences
 
 , was able to find water in so many places suggests that the Apollo beads are representative of the entire mantle.
 

 What’s impressive about this research is that it detects the presence of water without even landing on the moon. Satellite equipment measured the wavelengths of sunlight reflected by the moon in order to determine the minerals and compounds contained on the surface.
 

 This finding raises the question of the water’s origin. Scientists previously believed that the collision that formed the moon produced too much heat for water to survive. So either the collision wasn’t too hot, or something else must have brought the moon its water.
 
</section>

 Photo Credit: Olga Prilipko Huber

Will Sullivan

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