More stories

  • in

    How fossil footprints are revealing the joy and fear of Stone Age life

    A new wave of archaeological investigations is reconstructing intimate details of our ancestors’ lives from fossilised footprints. They give us glimpses of everything from parent-child relationships to the thrill of a giant sloth hunt

    Humans

    6 April 2022

    By Colin Barras
    Rupert Gruber
    A YOUNG woman is struggling across a muddy plain with a 3-year-old child on her left hip. She puts the youngster down to catch her breath. But she is too afraid to pause for long. The pair are alone, an easy target for the sabre-toothed cats that may lurk nearby. She picks up the child again and hurries on, vanishing into the distance. For a time, all is quiet. Then a giant ground sloth plods across the path she took. The animal catches the woman’s scent and is instantly on guard, rearing up and turning to scan the landscape for human hunters.
    What was it like to live in the Stone Age? There must have been moments of joy, fear, love, pain and perhaps even wonder for the people who inhabited Earth tens of thousands of years ago. But emotions don’t fossilise, so we are shut out of those moments, separated by a vast chasm of time. We can find all the bones and tools we like, but they won’t tell us about the experience of life for our ancient ancestors.
    Then again, a new window on their everyday existence may be cracking open. As people went about their lives, they left untold numbers of footprints behind. These recorded their behaviour in a unique way, capturing everything from nervous shuffles to determined sprints. What’s more, the tracks have an order to them, meaning events can be read like a narrative. That story of the woman, the child and the giant sloth is a vivid example we have found written in ancient tracks – but it certainly isn’t the only … More

  • in

    A star nicknamed ‘Earendel’ may be the most distant yet seen

    A chance alignment may have revealed a star from the universe’s first billion years.

    If confirmed, this star would be the most distant one ever seen, obliterating the previous record (SN: 7/11/17). Light from the star traveled for about 12.9 billion years on its journey toward Earth, about 4 billion years longer than the former record holder, researchers report in the March 30 Nature. Studying the object could help researchers learn more about the universe’s composition during that early, mysterious time.

    “These are the sorts of things that you only hope you could discover,” says astronomer Katherine Whitaker of the University of Massachusetts Amherst, who was not part of the new study.

    Sign Up For the Latest from Science News

    Headlines and summaries of the latest Science News articles, delivered to your inbox

    Thank you for signing up!

    There was a problem signing you up.

    The researchers found the object while analyzing Hubble Space Telescope images of dozens of clusters of galaxies nearer to Earth. These clusters are so massive that they bend and focus the light from more distant background objects, what’s known as gravitational lensing (SN: 10/6/15).

    In images of one cluster, astronomer Brian Welch of Johns Hopkins University and colleagues noticed a long, thin, red arc. The team realized that the arc was a background galaxy whose light the cluster had warped and amplified.

    Atop that red arc is a bright spot that is too small to be a small galaxy or a star cluster, the researchers say. “We stumbled into finding that this was a lensed star,” Welch says.

    The researchers estimate that the star’s light originates from only 900 million years after the Big Bang, which took place about 13.8 billion years ago.

    Welch and his colleagues think that the object, which they poetically nicknamed “Earendel” from the old English word meaning “morning star” or “rising light,” is a behemoth with at least 50 times the mass of the sun. But the researchers can’t pin down that value, or learn more about the star or even confirm that it is a star, without more detailed observations.

    The researchers plan to use the recently launched James Webb Space Telescope to examine Earendel (SN: 10/6/21). The telescope, also known as JWST, will begin studying the distant universe this summer.

    JWST may uncover objects from even earlier times in the universe’s history than what Hubble can see because the new telescope will be sensitive to light from more distant objects. Welch hopes that the telescope will find many more of these gravitationally lensed stars. “I’m hoping that this record won’t last very long.” More

  • in

    Binary stars keep masquerading as black holes

    As astronomy datasets grow larger, scientists are scouring them for black holes, hoping to better understand the exotic objects. But the drive to find more black holes is leading some astronomers astray.

    “You say black holes are like a needle in a haystack, but suddenly we have way more haystacks than we did before,” says astrophysicist Kareem El-Badry of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. “You have better chances of finding them, but you also have more opportunities to find things that look like them.”

    Two more claimed black holes have turned out to be the latter: weird things that look like them. They both are actually double-star systems at never-before-seen stages in their evolutions, El-Badry and his colleagues report March 24 in Monthly Notices of the Royal Astronomical Society. The key to understanding the systems is figuring out how to interpret light coming from them, the researchers say.  

    Sign Up For the Latest from Science News

    Headlines and summaries of the latest Science News articles, delivered to your inbox

    Thank you for signing up!

    There was a problem signing you up.

    In early 2021, astronomer Tharindu Jayasinghe of Ohio State University and his colleagues reported finding a star system — affectionately named the Unicorn — about 1,500 light-years from Earth that they thought held a giant red star in its senior years orbiting an invisible black hole. Some of the same researchers, including Jayasinghe, later reported a second similar system, dubbed the Giraffe, found about 12,000 light-years away.

    But other researchers, including El-Badry, weren’t convinced that the systems harbored black holes. So Jayasinghe, El-Badry and others combined forces to reanalyze the data.

    To verify each star system’s nature, the researchers turned to stellar spectra, the rainbows that are produced when starlight is split up into its component wavelengths. Any star’s spectrum will have lines where atoms in the stellar atmosphere have absorbed particular wavelengths of light. A slow-spinning star has very sharp lines, but a fast-spinning one has blurred and smeared lines.

    “If the star spins fast enough, basically all the spectral features become almost invisible,” El-Badry says. “Normally, you detect a second star in a spectrum by looking for another set of lines,” he adds. “And that’s harder to do if a star is rapidly rotating.”

    That’s why Jayasinghe and colleagues misunderstood each of these systems initially, the team found.

    “The problem was that there was not just one star, but a second one that was basically hiding,” says astrophysicist Julia Bodensteiner of the European Southern Observatory in Garching, Germany, who was not involved in the new study. That second star in each system spins very fast, which makes them difficult to see in the spectra.

    What’s more, the lines in the spectrum of a star orbiting something will shift back and forth, El-Badry says. If one assumes the spectrum shows just one average, slow-spinning star in an orbit — which is what appeared to be happening in these systems at first glance — that assumption then leads to the erroneous conclusion that the star is orbiting an invisible black hole.

    Instead, the Unicorn and Giraffe each hold two stars, caught in a never-before-seen stage of stellar evolution, the researchers found after reanalyzing the data. Both systems contain an older red giant star with a puffy atmosphere and a “subgiant,” a star on its way to that late-life stage. The subgiants are near enough to their companion red giants that they are gravitationally stealing material from them. As these subgiants accumulate more mass, they spin faster, El-Badry says, which is what made them undetectable initially.

    “Everyone was looking for really interesting black holes, but what they found is really interesting binaries,” Bodensteiner says.

    These are not the only systems to trick astronomers recently. What was thought to be the nearest black hole to Earth also turned out to be pair of stars in a rarely seen stage of evolution (SN: 3/11/22).

    “Of course, it’s disappointing that what we thought were black holes were actually not, but it’s part of the process,” Jayasinghe says. He and his colleagues are still looking for black holes, he says, but with a greater awareness of how pairs of interacting stars might trick them. More

  • in

    When the Magellanic Clouds cozy up to each other, stars are born

    Like two great songwriters working side by side and inspiring each other to create their best work, the Magellanic Clouds spawn new stars every time the two galaxies meet.

    Visible to the naked eye but best seen from the Southern Hemisphere, the Large and Small Magellanic Clouds are by far the most luminous of the many galaxies orbiting the Milky Way. New observations reveal that on multiple occasions the two bright galaxies have minted a rash of stars simultaneously, researchers report March 25 in Monthly Notices of the Royal Astronomical Society: Letters.

    Astronomer Pol Massana at the University of Surrey in England and his colleagues examined the Small Magellanic Cloud. Five peaks in the galaxy’s star formation rate — at 3 billion, 2 billion, 1.1 billion and 450 million years ago and at present — match similarly timed peaks in the Large Magellanic Cloud. That’s a sign that one galaxy triggers star formation in the other whenever the two dance close together.

    Sign Up For the Latest from Science News

    Headlines and summaries of the latest Science News articles, delivered to your inbox

    Thank you for signing up!

    There was a problem signing you up.

    “This is the most detailed star formation history that we’ve ever had of the [Magellanic] Clouds,” says Paul Zivick, an astronomer at Texas A&M University in College Station who was not involved in the new work. “It’s painting a very compelling picture that these two have had a very intense set of interactions over the last two to three gigayears.”

    Even as the two galaxies orbit the Milky Way at 160,000 and 200,000 light-years from Earth, they also orbit each other (SN: 1/9/20). Their orbit is elliptical, which means they periodically pass near each other. Just as tides from the moon’s gravity stir the seas, tides from one galaxy’s gravity slosh around the other’s gas, inducing star birth, says study coauthor Gurtina Besla, an astrophysicist at the University of Arizona in Tucson.

    During the last encounter, which happened 100 million to 200 million years ago, the smaller galaxy probably smashed right through the larger, Besla says, which sparked the current outbreak of star birth. The last star formation peak in the Large Magellanic Cloud occurred only in its northern section, so she says that’s probably where the collision took place.

    Based on the star formation peaks, the period between Magellanic encounters has decreased from a billion to half a billion years. Besla attributes this to a process known as dynamical friction. As the Small Magellanic Cloud orbits its mate, it passes through the larger galaxy’s dark halo, attracting a wake of dark matter behind itself. The gravitational pull of this dark matter wake slows the smaller galaxy, shrinking its orbit and reducing how much time it takes to revolve around the Large Magellanic Cloud.

    The future for the two galaxies may not be so starry, however. They recently came the closest they’ve ever been to the Milky Way, and its tides, Besla says, have probably yanked the pair apart. If so, the Magellanic Clouds, now separated by 75,000 light-years, may never approach each other again, putting an end to their most productive episodes of star making, just as musicians sometimes flounder after leaving bandmates to embark on solo careers. More

  • in

    Fate of buried Java Man revealed in unseen notes from Homo erectus dig

    One of the first excavations to find extinct human remains took place on Java in the 1890s, and the original documentation reveals details about the mudflow that encased the fossils there

    Humans

    30 March 2022

    By Michael Marshall
    Archaeological dig in Indonesia where the Java Man fossils were foundpublic domain sourced / access rights from Paul Fearn / Alamy Stock Photo
    The first large excavation of ancient human remains in Indonesia, in the 1890s, were done with great care – according to an analysis of unpublished documents from the dig.
    The original excavations revealed that Homo erectus on Java lived in a lush valley alongside a range of large animals, including antelope and elephants. Researchers including Paul C. H. Albers at the Naturalis Biodiversity Center in the Netherlands have analysed the records, and they say the animals in the fossil bed … More

  • in

    Europe must tackle its energy crisis now or face a very painful winter

    Martin Meissner/AP/Shutterstock
    “THE time to repair the roof is when the sun is shining,” US president John F. Kennedy once said. It is an adage that Europe must now wrestle with.
    With spring blossoming even as war continues to darken the continent, it is hard to spend too much time thinking about next winter. Yet the geopolitical uncertainty created by Russia’s invasion of Ukraine means volatile energy prices are guaranteed this year. UK energy bill projections for October have yo-yoed with oil and gas prices in recent weeks, from a high of £3000 a year on average to a still-very-high low of … More

  • in

    What is Regeneration? review: A dive into the science of regrowth

    From hydras to humans, this short book by two marine biologists explores the peculiar process of regeneration, showing that it is a far bigger subject than it might at first seem

    Humans

    30 March 2022

    By Simon Ings

    Is the regeneration of a forest after fire fundamentally the same as an animal regrowing a body part?KarenHBlack/Getty Images
    What Is Regeneration?
    Jane Maienschein and Kate MacCord
    University of Chicago Press (out 6 April)Advertisement

    SOME animals are able to grow an entire new body from tiny parts. Crabs and lobsters can regenerate lost tentacles and claws. Hydras and some worms can regrow their heads. We humans can replace our skin, hair, fingernails and even our liver.
    Regeneration is such a peculiar ability that, even in science, it is surprisingly under-researched. As a result, there is much we still don’t know. What Is Regeneration? is a collaborative effort between Jane Maienschein and Kate MacCord, both at the Marine Biological Laboratory in Woods Hole, Massachusetts, to fill some of the gaps. Together, they explore why regeneration occurs when it does, why it doesn’t always happen and what the process can tell us about the grander mysteries of birth, death and development.
    It turns out to be a seemingly simple phenomena that, on closer inspection, becomes far more complicated. For instance, are we thinking only about regeneration of structure, about regeneration of function or both? Is the regeneration of the gut flora in your intestines after a course of antibiotics or the regeneration of woodland after a forest fire at all similar to regrowing a body part?
    To try to pin it down, the authors begin with a history of the study of the subject, starting with Aristotle and ending with Magdalena Zernicka-Goetz’s ongoing research on cellular signalling. Their account pivots on the work of Thomas Hunt Morgan (better known as a pioneer of chromosomal genetics) and, in particular, his 1901 book Regeneration. Morgan, more than anyone before or since, attempted to establish clear boundaries around the phenomenon, and the terminology he came up with remains useful.
    He identified three kinds of regeneration. The first two are restorative regeneration, which occurs in response to injury, and physiological regeneration, which describes replacement, as when an elk moults its antlers and new ones grow in their place. The third, morphallaxis, refers to more extreme cases, such as when a hydra, cut into pieces, reorganises itself into a new hydra without going through the normal processes of cell division.
    The key to this categorisation is that the mechanisms of regeneration aren’t, as the authors put it, “a special response to changing environmental conditions but, rather, an internal normal process of growth and development”.
    So here is the problem: if the mechanisms of regeneration can’t be distinguished from those of growth and development, what is to stop everything ceaselessly regenerating? What dictates the process of regrowth and why does it happen only in some tissues, in some species and only some of the time?
    Maienschein and MacCord argue that, to fully understand this, we need to see regeneration as a window into the world of biology in general, and the complex feedback loops that decide what grows, divides and dies, where and when.
    Far from being an interesting curio, then, studying regeneration can tell us much about life in general, from a cellular level right up to the level of ecosystems, and inform everything from regenerative therapies using stem cells to ecosystem protection and recovery.
    Seen through this lens, regeneration is a far bigger subject than it might at first seem, and Maienschein and MacCord take fewer than 200 pages to anatomise the complexities and ambiguities that their simple question throws up. It is to their credit that they mostly focus on the big picture and don’t make the biology any more complex than it needs to be.

    More on these topics: More

  • in

    Don't miss: Apollo 10 1/2, a fantastical tale of a boy sent to space

    Netflix
    Watch
    Apollo 10 ½ sees Richard Linklater use the hallucinatory animation style of his A Scanner Darkly to tell the fantastical tale of a young space fan living in Houston, Texas, in 1969, when anything felt possible. Via Netflix.

    John McKenzie/courtesy the artist and Ingleby Gallery, EdinburghAdvertisement
    Visit
    Requiem features an urn full of dust gathered by artist Katie Paterson from meteorites, rocks, corals and other detritus. From 9 April, it will be the focal point of an exhibition at the Ingleby Gallery in Edinburgh, UK, that explores our planet’s past and future.

    Read
    Power in the Wild, by behavioural ecologist Lee Alan Dugatkin, reveals the realpolitik behind the lives of sweet-looking creatures from meerkats to field mice, as he examines the eternal struggle for dominance in nature.

    More on these topics: More