The photos Paloma showed me before we got there, though stunning, were of no help in looking for the fly. There were insects flying in every direction, their movements a blur, making it impossible to pick out any details. I only had a split second to figure out whether the thing I was seeing was a laphria, a similarly colored yellowjacket wasp, or something else entirely.
Despite their relatively crude vision, the flies I was looking for are far more adept than I am at picking out the insects they’re targeting. Somehow they’re able to zero in on their prey of choice: beetles. Based on her field observations the previous year, Paloma thought they did this by looking for the flash of beetle wings.
If she was right, laphria have hit upon an ingenious trick that balances the need for speed, accuracy and specificity. Here are some of the clues we’ve found to the secrets of their success.
Paloma had previously studied other predator insects such as dragonflies and killer flies. Their compound eyes don’t provide a lot of detail about the visual world, making it possible to trick them into chasing simple beads as if they were their prey insects.
But when Paloma tried the same sleight of hand on laphria, they wouldn’t go for the regular black beads. They chased only clear beads.
The one important difference between laphria and the other predators Paloma had studied is that they’re picky eaters. Their prey of choice are beetles. So, Paloma and our collaborator, Jennifer Talley, speculated that the reason laphria are attracted to shiny beads is because they reflected light and flashed like the clear wings of a beetle.
In Florida, we tested this idea by swapping out the plain black beads for a panel of LED lights that we could program to flash in sequence at a frequency that matched the wing beats of beetles, which can be anywhere from 80 to 120 beats per second.
The experimental setup, with a robber fly sitting on a log facing the LED light panel.
In an outdoor enclosure, Paloma placed previously caught robber flies one after the other on a log. Outside, Jennifer and I controlled the LED panel in front of the log and the high-speed cameras that captured the action.
The LED pixels flashed in sequence, simulating a moving target. Laphria tracked the lights with keen interest only when they flashed at the same frequency at which beetles flapped their wings.
But even as our initial experiments began confirming the hypothesis, a new puzzle presented itself. How do the flies accurately track their prey?
Before they give chase, all visual predators, including laphria, need to accurately track their prey’s movements. Although many animals have this ability, what we found in laphria was, to our surprise, a slightly tweaked formula compared with other predators. Their strategy allows them not only to accurately track but also count those flashes from their prey’s wing movements.
When I looked at the high-speed videos of laphria tracking the flashing LEDs and actual beetles, I noticed that they primarily moved their head in short bursts, called saccades, interspersed with little or no other movements. These saccades are extremely quick, lasting less than 40 milliseconds, and the time between them is only slightly longer. To the naked eye, this looks like continuous motion, but our high-speed videos show otherwise. The degree to which the flies moved their heads during each burst depended on the speed of the target and how far off center it was from the direction of the fly’s gaze.
Watch a robber fly watching moving lights it perceives as a prey beetle.
What our findings told us is that instead of continuously moving their heads to maintain the position of the target within the most sensitive parts of their eyes, laphria allow it to pass over their retina, moving only when it slips out of focus. We think this strategy helps them count the flashes of the prey’s beating wings, which determines their continued interest.
That is, the laphria know the wingbeat frequency of their most tasty prey and so pay attention to flashes that match. If the flash count matches their expectations, they will continue to track the target after it slips out of the sensitive zone of their eyes.
To bring it back into focus, though, they have to account for its speed and the position where they last saw it. Because the size of the saccade matches the speed of the prey, we think the laphria are keeping track of how fast the prey moves while at the same time counting the flashes from its wingbeats. So once a beetle slips out of focus, the predator knows how much to move its head to refocus.
Even though people track moving objects all the time – like while playing sports such as baseball or tennis or even just while watching a bird fly by – it’s a complex process. It involves dynamic cross-talk between the visual and muscular systems.
Regardless of the motivation, the goal while visually tracking a target is the same – to train the most sensitive zone of the eyes, known as the fovea, onto the item of interest. Laphria saffrana have seemingly tweaked that rule so they can learn more about the target. Their customized prediction strategy allows them to accurately locate and quickly chase down their very specific dietary needs.
Siddhant Pusdekar, Graduate Researcher in Ecology, Evolution and Behavior, University of Minnesota
This article is republished from The Conversation under a Creative Commons license. Read the original article.
This all played out against the backdrop of the Inquisition and colonization, when the Catholic Church prosecuted heresy. Consolidating religious norms promoted health care through charitable activity, such as the creation of hospitals, but also created challenges between the authority of the Catholic Church and competing health care initiatives.
My research focuses on how health and medical practices in early modern Latin America and Spain are represented through cultural artifacts, including literature, recipe books, the Inquisition and convent records. In our book, my colleague Sarah Owens and I explore how gender norms affected medicine and health care. We also consider how popular representations of health and medicine in culture inform widely held beliefs and biases about these experiences.
Understanding the historical roots of health disparities in Hispanic communities can help address them both locally and globally today.
Latin America and Spain in the late 15th to 18th centuries were home to a number of medical practices, including traditional medical knowledge and remedies and the professionalization of medicine through new universities and licensing systems.
Early modern medical humanists, or Renaissance clinicians, took up medical treatises by the ancient Greek and Roman physicians, including those of Galen and Hippocrates, and revived them in the context of “learned” medical instruction through European universities. The study of Paracelsianism, or the theories of Swiss physician Paracelsus, though more contested among practitioners because of its connections to the supernatural and occult, also affected a variety of health practices across early modern Spain and colonial Latin America. With the publication of anatomical treatises at the start of the 16th century, including the work of Renaissance physician Andreas Vesalius, the study of anatomy slowly and dramatically changed medical practice.
An 18th century engraving depicts a woman soothing a wound on Don Quixote’s back. William Hogarth/Wellcome Collection
Traditional healing practices varied significantly but often provided accessible and culturally compatible care, including reduced language barriers. Many people in Hispanic communities still rely on these practices today. Discussions about the legitimacy and health effects of folk remedies in Latin America, such as varieties of herbal and holistic medicine and other animal-based remedies, are ongoing.
As health care became more professionalized during the early modern period, some women found ways to practice medicine in more formalized contexts, while others continued to work as healers or herbalists. These practices alternated between success and suspicion during the Spanish Inquisition. Accusations of sorcery and witchcraft along with sexualities outside heterosexual norms often collided with practices of health and medicine.
But just as pregnancy and child–rearing are not the only medical events that shaped early modern women’s lives, women medical providers weren’t only witches. Nuns in Arequipa prepared treatments in convents, and mothers and daughters made medicine within households in Madrid.
From Fernando de Rojas’ 1499 tragicomedy “La Celestina,” about the go-between who crafts love potions and repairs hymens, to the 2019 Colombian TV series “Siempre Bruja,” about a 17th century Afro-Colombian witch who finds herself in present-day Cartagena, the cultural legacy of witchy women healers in the Hispanic world continues to be deeply felt.
The transfer of plants, animals and diseases across the Atlantic also profoundly affected health outcomes.
European diseases such as smallpox devastated Indigenous populations. Meanwhile, plants from the Americas offered novel treatments for a number of illnesses globally. Peruvian cinchona bark is a natural source of quinine that proved effective against malaria, a disease prevalent in both Europe and the Americas. Other plants such as cacao seeds found various medicinal and ritual uses, including relieving exhaustion or anxiety or improving weight gain.
The Columbian Exchange was not mutually beneficial.
But access to this range of treatment methods was unequal, especially across social class and geography. Wealthier nobility in urban centers often had much greater access to scarce resources across the Iberian empire.
Health outcomes were also often linked to racial and ethnic hierarchies. Patients were classified as Spanish, mestizo – mixed European and Indigenous – or African slaves in treatment records. These documents show evidence of uneven access to care, while there is also evidence that some exchanges in care practices across these hierarchies were possible.
‘Grammar of the Castilian Language’ codified Spanish. Antonio De Nebrija/World Digital Library via Library of Congress
Forced displacement as well as language discrimination also affected health access and outcomes. Spanish wasn’t standardized as a language until the publication of Antonio de Nebrija’s “Grammar of the Castilian Language” in 1492, inscribed to Queen Isabel with the reminder that “language has always been the companion to empire.”
For example, while Arabic and Hebrew were widely spoken throughout the Iberian Peninsula before the forced expulsions of the Inquisition, politics around language resulted in centuries of stereotypes and discrimination against Muslim and Jewish medical providers, who had to navigate alternative licensing methods to practice medicine in Spain and its colonial territories.
More than 400 years later, inequities in and commodification of Hispanic health and wellness continue.
Luxury travelers are sold wellness via Mayan purification rituals, among other assorted local remedies and practices that can be purchased, marketed and monetized. Wood from the Palo Santo tree, which healers have used for centuries for spiritual cleanings and pain relief, continues to be grown all over the Americas, including Mexico, Peru and Ecuador, and is now bought and sold globally to bring “good vibes.”
Considering these early modern health practices and inequities allows for deeper engagement with health care systems today. Informed critical thinking about medicine and health care across disciplines is a powerful way to consider how these histories continue to shape current values and practices, including ongoing disparities in health care.
One such discipline is narrative medicine. Using the tools of the humanities, physicians can broaden their view of their patients from simple metrics to human beings with stories to tell. This process involves perceiving and incorporating patients’ personal experiences, valuing narration of the past and recognizing the significance of the encounter between doctor and patient. While much of this research focuses on English-language narratives, cross-cultural and bilingual research in Spanish is expanding the field.
It is estimated that by 2060 there will be more than 111 million Latinos in the United States. Understanding the historical legacies that have shaped wellness and care practices, including the factors that determine care quality and access, can promote more equitable and culturally nuanced health outcomes.
Margaret Boyle, Associate Professor of Romance Languages and Literatures, Director of Latin American, Caribbean, and Latinx Studies Program, Bowdoin College
This article is republished from The Conversation under a Creative Commons license. Read the original article.
A new study, published in Nature, provides an explanation for our error-prone early development by looking at the genetic changes that enabled our ancestors to lose their tails.
Current estimates suggest that about half of all fertilised eggs never even make it to be recognised pregnancies and that for every child born about two never made it to term. In fish and amphibians, such early death is unheard of. Of those of us lucky enough to be born, a little under 10% will suffer one of the many thousand “rare” genetic diseases, such as haemophilia. The not so rare diseases, such as sickle cell disease and cystic fibrosis, affect yet more of us.
Surely this wouldn’t be the case in an evolutionary successful species? Where is the progress?
There are multiple possible solutions to this problem. One is that, compared to other species, we have an unusually high mutation rate. There’s a relatively high likelihood that in your DNA there will be a change that wasn’t inherited by either your mother or father. You were probably born with between ten and 100 such new changes to your DNA. For most other species that number is under one – often far under one.
There are other solutions too. One of the more obvious differences between us and many primate relatives is that we don’t have a tail. The loss of the tail happened around 25 million years ago (for comparison our common ancestor with chimps was about 6 million years ago). We still have the coccyx as an evolutionary hangover from this tail-bearing ancestry.
Tail loss occurred in our ape ancestors at the same time as the evolution of a more erect back and, in turn, a tendency to use only two of the four limbs to support the body. While we can speculate on why these evolutionary changes may be coupled, that doesn’t address the problem of how (rather than why) tail-loss evolved: what were the underlying genetic changes?
The recent study looked at just that question. It identified an intriguing genetic mechanism. Many genes combine to enable the development of the tail in mammals. The team identified that primates without a tail had one additional “jumping gene” – sequences of DNA that can transfer to new areas of a genome – in a one such tail-determining gene, TBXT.
Much more of our DNA is the remains of such jumping genes than is sequence specifying proteins (the classical function of genes), so the gain of a jumping gene is nothing special.
What was unusual was the effect that this new addition had. The team also identified that the same primates also had an older but similar jumping gene just a little bit of a distance away in the DNA also embedded within the TBXT gene.
The effect of these two in close proximity was to alter the processing of the resulting TBXT messenger RNA (molecules created from DNA that contain instructions for how to make proteins). The two jumping genes can stick to each other in the RNA, causing the block of RNA between them to be excluded from the RNA that gets coded into protein, resulting in a shorter protein.
To see the effect of this unusual exclusion, the team genetically mimicked this situation in mice by making a version of the mouse Tbxt gene that was also missing the excluded section. And indeed, the more of the form of the RNA with the section of the gene excluded, the more likely that the mouse would be born without a tail.
We have then a strong candidate for a mutational change that underpins the evolution of being tailless.
But the team noticed something else odd. If you make a mouse with only the form of the Tbxt gene with the section excluded, they can develop a condition that closely resembles the human condition spina bifida (when the spine and spinal cord fail to develop properly in the womb, causing a gap in the spine). Mutations in human TBXT had previously been implicated in this condition. Other mice had other defects in the spine and spinal cord.
The team suggest that just as the coccyx is an evolutionary hangover of the evolution of being tailless that we all have, so too spina bifida may be a rare hangover resulting from the disruption to the gene that underpins our lack of a tail.
Being tailless, they suggest, was a large advantage, and so an increase in incidences of spina bifida was still worth it. This may be the case for many genetic and development diseases – they are an occasional byproduct of some mutation that on balance helped us. Recent work, for example, finds that the genetic variants that help us fight pneumonia also predispose us to Crohn’s disease .
This goes to show how misleading the march of progress really can be. Evolution can only deal with the variation that is present at any time. And, as this latest study shows, many changes also come with costs. Not so much a march as a drunken stumbling.
Laurence D. Hurst, Professor of Evolutionary Genetics at The Milner Centre for Evolution, University of Bath
This article is republished from The Conversation under a Creative Commons license. Read the original article.
The situation has not improved in the years since Reynolds voiced his concerns. Our fixation on the popular music of previous decades threatens our future by stifling originality.
Thanks to recording technology, and now to more recent developments in artificial intelligence and machine learning, we find ourselves more and more in a spectral present, thoroughly haunted by the ghosts of pop music’s past.
This type of hauntedness can provoke anxiety. Hauntology, a theoretical concept originating in the work of French philosopher Jacques Derrida, was later applied to musicology by critic Mark Fisher. Hauntology is concerned with memory, nostalgia and the nature of being. The present is never simply “present,” and the remnants of our cultural past always linger or return.
A ghost, in literature, folklore and popular culture, is a presence from the past of something or someone that no longer remains. Is a ghost, then, from the past or of the present? As hauntology would insist, a ghost is paradoxically both at the same time.
In November 2023, pop phenomenon the Beatles released a “new” song titled “Now and Then.” It received a rapturous reception from fans and critics alike, and was soon topping the charts in the United States and the United Kingdom, becoming the fastest-selling single of 2023.
The Beatles’ 2023 track “Now and Then.”
The song features a lead vocal track by the late John Lennon, salvaged from a demo recording he made at home in the late 1970s, just a few years before his murder in 1980. It also includes archival guitar tracks from the late George Harrison.
The two surviving Beatles, Paul McCartney and Ringo Starr, contributed new bass, drum, vocal and guitar parts (McCartney even played a slide guitar solo mimicking Harrison’s sound and style), and producer Giles Martin (son of legendary Beatles’ producer George Martin) provided a string arrangement and a tapestry of background vocals lifted from other iconic Beatles songs.
“Now and Then” was also celebrated for the technological sophistication of its production, and specifically for its use of artificial intelligence. Using software that could tell the difference between a human voice and other sounds on a recording, Lennon’s voice was isolated and reanimated, allowing McCartney and Starr to perform alongside their long-deceased bandmate.
“Now and Then,” in addition to being a “new” Beatles tune, is likely also the group’s last: there are no more old recordings to resurrect, and McCartney and Starr are both octogenarians.
Indeed, according to music critics like The Guardian’s Alexis Petridis, “Now and Then” is an emotionally satisfying “act of closure.” It stands on its own as a genuine addition to the Beatles’ catalogue, wrapping up the band’s career and “never stoops to deploying obviously Beatles-y signifiers.”
Music journalist Jem Aswad, writing in Variety, characterizes “Now and Then” as a “bittersweet finale.” While Aswad is mildly critical of the song as an “incomplete sketch,” he insists at the same time that any further criticism is just unwarranted sour grapes, concluding that it is “an unexpected pleasure that marks the completion of the group’s last bit of unfinished business.”
Some critics, however, echoing Reynolds’s concerns, found “Now and Then” decidedly less praiseworthy. Josiah Gogarty’s brutal review, published in UnHerd, argues that the song serves as “a sign of our cultural doom loop,” and likened it to a “séance, calling forth the warbling and the jangling of the dead.”
The recording includes McCartney’s count-in at the beginning and some studio chatter from Starr at the end, as if to reassure listeners that the song is a product of living musicians.
At the same time, the song is eerily placeless or ahistorical, caught somewhere between past and present: a haunted, ghostly thing, evidence of a pop culture that has long ceased to evolve.
The problem is the way songs like “Now and Then” are imbued with nostalgia: they threaten the future and limit the possibility of the emergence of new ideas.
Fisher feared the effect of this sort of nostalgia giving rise to “a cancelled future.” We can readily imagine such a future, because we already inhabit it: a future of never-ending tours by impossibly decrepit rock bands, countless re-boots of old movies and television shows, the fetishization of all that is vintage.
Even the most stunningly progressive technological developments — such as the AI that made “Now and Then” possible — turns out to serve a regressive purpose, namely to resurrect the Beatles.
A generous take on “Now and Then” would be to view its arrangement and production as capturing and amplifying the meaning of the song lyrics: “Now and then I miss you … I want you to return to me.” These lyrics suggest the presence and absence theorized by hauntology, which is cleverly reflected in the song’s haunted soundscape.
Less generously, “Now and Then,” rather than an act of closure, simply continues an ongoing trend of looking backwards in pop music. It indicates that our insecurities about our future ensure we will remain forever entangled with its ghosts.
Alexander Carpenter, Professor, Musicology, University of Alberta
This article is republished from The Conversation under a Creative Commons license. Read the original article.
