Philippa Kaur

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    in Humans

    Your body wash may make you more attractive to mosquitoes

    Mosquitoes may pick up on the fragrances in body washesbrizmaker/iStockphoto/Getty Images
    The body wash you use in the shower may react with your natural odour to make you more attractive to mosquitoes.
    Mosquitoes use various methods to find a target for their next blood meal, such as detecting an animal’s body heat, odour and the carbon dioxide they emit.
    To learn if the body wash we use may have an effect, Clément Vinauger at Virginia Polytechnic Institute and State University and his colleagues selected varieties from the brands Dial, Dove, Native and Simple Truth.Advertisement
    First, they placed two strips of nylon on one of the forearms of four volunteers and wrapped that area in foil, to collect the participants’ natural odour.
    Next, the researchers washed part of each participants’ other forearm with about 1 gram of one of the body washes for 10 seconds, before rinsing it with water for a further 10 seconds. They then similarly applied two strips of nylon and foil to these forearms, to collect the wash’s scent. The researchers repeated this with the three other body washes.
    One hour after each sample was taken, they took two strips – one from each of the body wash-exposed areas and one from the body wash-free areas – for chemical analysis while the other body wash-free and body wash-exposed strips were put in separate cups.
    The researchers placed these inside cages with 16 to 25 female Aedes aegypti mosquitoes, which can transmit yellow fever, that were free to visit either cup.
    The Simple Truth body wash appeared to increase the attractiveness of all of the participants, measured by the number of times the mosquitoes landed on their body wash-exposed strips compared with their body wash-free strips. The Dove wash had a similar effect, but the increase in attractiveness was only pronounced for three of the participants.
    Dial’s body wash similarly made the participants more attractive to mosquitoes, but to a lesser extent than Simple Truth’s or Dove’s.
    In contrast, the mosquitoes tended to avoid the strips washed in the Native body wash, but displayed a particularly strong aversion towards one participant’s Native-washed strip.
    This suggests the body washes’ fragrances and the participants’ individual odours combined to create a scent that was detectable to the mosquitoes.
    “Our study highlights the importance of the interaction between the specific soap chemicals and the body odour of each person in determining whether a person would become more or less attractive to mosquitoes after applying soap to their skin,” says Vinauger.
    The experiment’s chemical analysis suggests that the compounds benzaldehyde, benzyl benzoate and γ-nonalactone may repel mosquitoes.

    The researchers are planning to repeat their study with a larger group of participants and more body washes, and will investigate how long a wash’s potential mosquito-attracting or mosquito-repelling effects last after it is washed off the skin.
    “The discovery that personal care products may cause mosquitoes to be attracted or repelled by the user opens the door for developing user-friendly mosquito repellents,” says Walter Leal of the University of California, Davis.
    “The chemicals in such products may not directly affect mosquito behaviour, but they may disrupt the specific ratio of human emissions that attract mosquitoes,” he says. “Regardless of the mechanism, reducing human-mosquito interactions mitigates the transmission of vector-borne diseases.”
    New Scientist contacted the four body washes’ manufacturers for comment but received no reply prior to publication.

    Topics:Mosquitoes/Hygiene More

  • 150 Shares119 Views

    in Humans

    The mental tricks you can use in your lifelong pursuit of happiness

    SolStock/Getty Images
    MORE than 2300 years ago, Aristotle argued that happiness was the highest good. Later, the US founding fathers considered its pursuit to be an unalienable human right. These days, you will find countless books promising to reveal the secrets of a happy life. But have millennia of philosophical and scientific enquiry taught us anything about how to achieve that?
    First, let’s look at how people who study happiness measure it. One of the most common strategies is to ask people to rate statements such as “In most ways, my life is close to my ideal” and “If I could live my life over, I would change almost nothing”. These aim to capture someone’s overall satisfaction with life, rather than their mood on a specific day.
    That makes sense, says Richard Layard, co-director of the Community Wellbeing Programme at the London School of Economics, because asking people to sum up their general contentment is often more practical than measuring their emotional state over an extended period. The other thing, says Layard, is that general contentment fits better with philosophical definitions of happiness as an overarching quality, as opposed to transient pleasures.
    Using this kind of scale, psychologists have attempted to identify the specific ingredients that contribute to happiness. Contrary to the idea that “money can’t buy happiness”, income does play a role: it is easier to feel pleased with your lot when you don’t have to worry about bills and can treat yourself to luxuries.
    We are also influenced by the riches of others – we are less happy if we know our neighbour is earning more than us. … More

  • 150 Shares139 Views

    in Humans

    What is longtermism and why do its critics think it is dangerous?

    Shutterstock/sumikophoto
    IMAGINE a child, running barefoot through a forest, and a broken glass bottle buried just beneath the soil. What’s worse: that a present-day child steps on the shards, or that a child in 100 years from now does?
    This question, posed by philosopher Derek Parfit in the 1980s, was intended to clarify our moral obligations towards unborn generations. Knowingly risking harm to a future person, he argued, is just as bad whether it is today or in a century.
    Parfit’s ideas inspired a branch of moral philosophy called longtermism. It rests on three premises: future people matter, there could be a lot of them and we have the power to make their lives better or worse. Ensuring the future goes well should therefore be a key moral priority of our time.
    All of which seems reasonable, at first glance: it apparently promotes the universal values of stewardship, the duty to posterity and being a “good ancestor”. But longtermism has proven controversial, with some critics arguing that it is a “dangerous ideology” that permits or even encourages the suffering of people alive today.
    Is that fair? To make up your own mind, the first thing you need to know is that longtermism comes in different flavours. Many of the most strident criticisms focus on the implications of “strong longtermism”, a variant introduced in a 2021 paper by the University of Oxford’s Hilary Greaves and William MacAskill, which says that it should be the top moral priority of our time.
    This would have striking consequences for how money is spent in the real world. Indeed, it is already having an influence. … More

  • 150 Shares129 Views

    in Space & Astronomy

    The James Webb telescope revealed surprise asteroids in the Fomalhaut star system

    The star Fomalhaut is ready for its close-up.

    Rings of dust encircle the young star in stunning new images from the James Webb Space Telescope. The photos offer a clearer view of the star system — already famous for previous images of a purported, now widely disputed, planet. Features in the system include an oddly cockeyed asteroid belt, an expanding cloud of debris from a possible planet collision, and other unidentified bits that hint at a dynamic and crowded environment, researchers report May 8 in Nature Astronomy. 

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    “It’s the first time we’re actually looking at the inner system, and it looks really different than I think anybody expected it to,” says astrophysicist Meredith MacGregor of the University of Colorado Boulder, who was not involved in the study. “The expectation was that there would be something like our solar system,” a place that is relatively mature and stable. “It really starts changing how we think about the dynamics of the [Fomalhaut] system.”

    Fomalhaut, a scant 25 light-years away, is a young star at the center of a rapidly evolving planetary system. It was once thought to host one of the first planets to be photographed outside of our solar system (SN: 11/13/08). However, the existence of the planet — dubbed Dagon — has long been in question (SN: 1/26/12). 

    The new JWST images add to the growing evidence that Dagon is actually a cloud of dust. A collision among planets probably explains the dusty feature, says András Gáspár, an astronomer at the University of Arizona in Tucson. “It is fading, and it is expanding in size,” he says, as it follows a trajectory consistent with dust blowing in the stellar wind from Fomalhaut. Those are all characteristics more indicative of dust clouds than planets.

    But just because Dagon hasn’t seemed to have panned out, that doesn’t mean there aren’t other planets lurking around Fomalhaut.

    Indirect evidence for other worlds comes from an unexpected asteroid belt, seen for the first time in the new images. The belt is tilted at a jaunty 23 degrees from everything else seen in orbit around the star.

    “This is a truly unique aspect of the system,” Gáspár says. The tilted belt, he says, could be the result of as-yet-undiscovered planets stirring up the debris around Fomalhaut.

    MacGregor agrees. “If you see a disk that’s like this, that has an [elongated] outer ring and a bunch of dust that’s getting dragged in, there are probably planets there,” she says. “I think the easiest explanation [for the tilted belt] is there’s a planet in there, and the planet is on an orbit that is not aligned with the disk.” The misaligned planet, in turn, is dragging the asteroid belt off-kilter with respect to the plane of the solar system, she says.

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    The JWST images also turned up a newly identified feature in the outer belt around the star.  It’s a blob that Gáspár and his colleagues call the Great Dust Cloud. It’s not yet clear whether it’s a real feature, or just some bright object shining through from beyond the Fomalhaut system.

    “It could easily be a background galaxy,” Gáspár says, “which would be a really cruel trick by nature.” Follow-up observations with JWST will help them decide, he says. If the object stays put while the Fomalhaut system keeps spinning, then it’s a cosmic photobomber, lurking in the background.

    The latest images answer some questions about Fomalhaut while raising a host of new ones, Gáspár says. “This single observation of Fomalhaut revealed way too many aspects of the system that we need to understand and unpack,” he says. “We set out to spatially resolve the asteroid belt component but ended up opening a much greater box of surprises.” More

  • 125 Shares119 Views

    in Humans

    Your saliva may determine which types of wine you prefer

    Wine drinkers have a lot of options when choosing their preferred varietyKlaus Vedfelt/Getty Images
    Variations in our salivary proteins may explain why different people can like different wines. Researchers have linked the concentrations of two types of proteins to how intense wine drinkers find a wine’s notes, such as fruity or floral, and their preferences for the alcoholic drink.
    A person’s wine preferences may at least partially come down to their cultural background, knowledge of the drink and individual taste. But Kate Howell at the University of Melbourne, Australia, and her colleagues … More

  • 188 Shares99 Views

    in Space & Astronomy

    A streak of light may not be a black hole fleeing its galaxy after all

    A trail of starlight thought to possibly indicate a runaway supermassive black hole may be something much more mundane: a spiral galaxy seen edge on, a new study finds.

    In February, astronomer Pieter van Dokkum of Yale University and colleagues reported spotting a line of stars near a compact galaxy in Hubble Space Telescope images. The researchers’ analysis suggested that three galaxies had interacted and merged, kicking a supermassive black hole out of its host galaxy (SN: 3/10/23). The black hole then traveled through a nearby gas cloud, the scenario goes, triggering the formation of stars in a line that points toward the home galaxy and revealing the black hole’s madcap escape.

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    But other researchers have been skeptical of this interpretation, with some suggesting that the scenario is too complex to explain the linear feature. In the new study, “we decided to explore what we thought was the most simple explanation,” says astronomer Ignacio Trujillo of the Instituto de Astrofísica de Canarias in Tenerife, Spain.

    He was inspired by a data plot in the original study, which compared the velocities of the stars in the linear feature with their positions, a comparison known as a velocity curve. To him, it looked like a spiral galaxy’s plot of its pinwheel rotation, where the stars in the galactic disk all move at nearly the same speed, no matter if they appeared to travel toward or away from Earth (SN: 8/17/21). That, combined with van Dokkum and colleagues’ estimate of the feature’s mass — roughly 100 million suns, which was surprisingly large for a simple line of stars — implied that the object is actually a spiral galaxy viewed on its edge, Trujillo says.

    So he and his colleagues compared characteristics of the linear feature with those of a well-studied spiral galaxy called IC 5249, which astronomers know we see edge on from Earth. The team looked at the objects’ masses, surface brightnesses and general motions of stars. The properties of the galaxy and linear feature matched closely, the researchers report in the study, which is in press in Astronomy & Astrophysics and was also submitted April 24 at arXiv.org.

    For now, “the evidence is not conclusive either way,” says astrophysicist Christopher Conselice of the University of Manchester in England who studies galaxy evolution and was not involved in either study.

    “A black hole being ejected from a galaxy would be really cool,” Conselice says. “But I think the simple explanation is that it’s either an edge-on galaxy, or some kind of filament or tidal debris,” left over from some previous galaxy interaction.

    Van Dokkum still favors the black hole scenario, in part because of one new image. In the original Hubble images, the linear feature merely points toward a compact galaxy at its left. In a new ultraviolet image, from the Very Large Telescope in Chile, “you start to see that this feature is actually connected to the galaxy,” which strengthens the runaway black hole theory, he says.

    Trujillo and his colleagues suggest that the edge-on spiral galaxy and compact galaxy are independent structures but members of the same galaxy group, coincidentally close to each other from our viewpoint.

    The debate’s resolution may have to wait at least until this summer when better imagery from Hubble arrives. More

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    in Humans

    How maths reveals the best time to add milk for hotter tea

    Claire Plumridge
    PICTURE the scene: you are making a cup of tea for a friend who is on their way and won’t be arriving for a little while. But – disaster – you have already poured hot water onto a teabag! The question is, if you don’t want their tea to be too cold when they come to drink it, do you add the cold milk straight away or wait until your friend arrives?
    Luckily, maths has the answer. When a hot object like a cup of tea is exposed to cooler air, it will cool down by losing heat. This is the … More

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    in Humans

    DNA from 25,000-year-old tooth pendant reveals woman who wore it

    A pierced deer tooth discovered in Denisova cave in SiberiaMax Planck Institute for Evolutionary Anthropology
    DNA that seeped into an elk tooth pendant about 25,000 years ago has yielded clues about the ancient woman who wore it.
    The tooth, worn as a necklace bead, probably absorbed DNA from the person’s sweat as it lay against her chest and neck. Marie Soressi at Leiden University in the Netherlands and her colleagues were able to extract that DNA without damaging the tooth through a new process that took eight years to develop. The technique might reveal unprecedented details about the social customs and gender roles of ancient populations, says Soressi.
    “For the first time, we can link an object to individuals,” she says. “So, for example, were bone needles made and used by only women, or also men? Were those bone-tipped spears made and used only by men, or also by women? With this new technique, we can finally start talking about that and investigating the roles of individuals according to their biological sex or their genetic identity and family relationships.”Advertisement
    Scientists have often suspected that ancient tools, weapons, ornamental beads and other crafted artefacts contain DNA from the people who touched them. But getting DNA out of these objects typically means removing sections for analysis – causing permanent damage. “We absolutely didn’t want to do that,” says Soressi.
    To see if DNA could be coaxed out of ancient artefacts without destroying them, Soressi and her colleagues tested numerous combinations of chemicals and heating regimes on 10 previously excavated artefacts from Palaeolithic caves in France. They found that placing them in a sodium phosphate solution and raising the temperature incrementally from 21°C to 90°C (70°F to 194°F) led to the release of relatively large amounts of human DNA with no damage to the specimens.
    The team then tested the procedure on another 15 excavated bone specimens from one of the caves. Genetic sequencing revealed DNA from many different humans – probably the scientists and technicians who had worked with the artefacts across the years, says Soressi.
    To avoid such modern DNA contamination, the researchers then tried their technique on four tooth pendants excavated by colleagues in Russia and Bulgaria who wore sterile gloves and face masks. Their analysis revealed mostly animal DNA that matched the species used to make the pendants.
    One tooth pendant from Denisova cave in Russia, however, also contained human DNA fragments, primarily from a single individual. There was enough genetic material for the researchers to positively identify a female Homo sapiens, in addition to the elk (Cervus canadensis) that provided the tooth.
    While the human might have rubbed her DNA into the pendant if she had crafted it, the large quantity of DNA recovered suggests she was the individual who wore it, says Soressi. “As a porous material, that tooth was likely soaking in sweat,” she says. “It worked like a sponge, pulling in that human DNA and trapping it there for 25,000 years.”
    The DNA showed that the woman was closely related to an ancient tribe that, thus far, had only been found more than 1500 kilometres to the east.

    Daniella Bar-Yosef Mayer at Tel-Aviv University, Israel, finds the paper “very exciting”, in part because it could help explain the purpose of ancient jewellery. For example, it might signal something about the identity of the wearer or their group, or their marital status, she says. “If we find them in different contexts on men, on women or children of this species or another species, or different age groups, that would give us some better clues about what they’re meant for.”
    The technique might also help resolve long-running scientific debates about whether certain artefacts were made and worn by Homo sapiens or Neanderthals, she adds.
    The study could open the door to DNA analyses of museum artefacts across the globe, says David Frayer at the University of Kansas. “Curators are often hesitant to allow their specimens to be damaged for DNA analysis, however small the extraction,” he says. “The absolute strength of this paper is that [their] procedure gets around that. If it can be extended to specimens cleaned long ago, this would represent a great leap forward for ancient DNA work.”

    Topics:DNA/ancient humans More