Connect with us

The Conversation

Robber flies track their beetle prey using tiny microbursts of movement

Published

on

Robber flies track their beetle prey using tiny microbursts of movement

Robber flies visually track their prey before spearing it with their proboscis.
Paloma Gonzalez-Bellido, CC BY-ND

Siddhant Pusdekar, University of Minnesota

April in the Florida Panhandle. It was hot, humid, and a thunderstorm was lurking. But as a fresh graduate student, I was relieved for the escape from my first brutal Minnesota winter. I was accompanying my adviser, Paloma Gonzalez-Bellido, on a project that would end up dominating my Ph.D. work. Out in the scrubland, my eyes darted at every movement, on the alert for an insect that likes shiny beads.

Laphria saffrana, also known as robber flies, are chunky black and yellow flies. Most of a laphria’s head is made up of its large eyes, between which sits a formidable proboscis – a long, tubular mouthpart that can deliver a potent venom capable of incapacitating prey in a heartbeat.

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.

Following the flash

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?

Unique strategy to track and identify

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.The Conversation

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.

The Conversation

Hundreds of 19th-century skulls collected in the name of medical science tell a story of who mattered and who didn’t

Published

on

theconversation.com – Pamela L. Geller, Associate Professor of Anthropology, University of Miami – 2024-11-14 07:23:00

Hundreds of 19th-century skulls collected in the name of medical science tell a story of who mattered and who didn’t

Illustration of just one of almost a thousand skulls Morton and colleagues collected.

Crania Americana by Samuel Morton, CC BY

Pamela L. Geller, University of Miami

When I started my research on the Samuel George Morton Cranial Collection, a librarian leaned over my laptop one day to share some lore. “Legend has it,” she said, “John James Audubon really collected the skulls Morton claimed as his own.” Her voice was lowered so as not to disturb the other scholars in the hushed archive.

As my work progressed, I uncovered no evidence to substantiate her whispered claim. Audubon had collected human skulls, several of which he then passed on to Morton. But birds and ornithology remained Audubon’s passion.

Nevertheless, the librarian’s offhanded comment has proven useful – a touchstone of sorts that continues to remind me of the controversy and confusion long surrounding the Morton Collection.

Morton was a physician and naturalist who lived in Philadelphia from 1799 until the end of his life in 1851. A lecture he delivered to aspiring doctors at the Philadelphia Association for Medical Instruction outlined the reasons for his cranial compulsion:

“I commenced the study of Ethnology in 1830; in which year, having occasion to deliver an introductory lecture on Anatomy, it occurred to me to illustrate the difference in the form of the skull as seen in the five great races of men … When I sought the materials for my proposed lecture, I found to my surprise that they could be neither bought nor borrowed.”

He would go on to acquire almost 1,000 human skulls.

Morton used these skulls to advance an understanding of racial differences as natural, easily categorizable and able to be ranked. Big-brained “Caucasians,” he argued in the 1839 publication “Crania Americana,” were far superior to small-skulled American Indians and even smaller-skulled Black Africans. Many subsequent scholars have since thoroughly debunked his ideas.

Certainly, condemnation of Morton as a scientific racist is warranted. But I find this take represents the man as a caricature, his conclusions as foregone. It provides little insight into his life and the complicated, interesting times in which he lived, as I detail in my book “Becoming Object: The Sociopolitics of the Samuel George Morton Cranial Collection.”

My research demonstrates that studies of skulls and diseases undertaken by Morton and his medical and scientific colleagues contributed to an understanding of U.S. citizenship that valued whiteness, Christianity and heroic masculinity defined by violence. It is an exclusionary idea of what it means to be American that persists today.

Yet, at the same time, the collection is an unintended testament to the diversity of the U.S. population during a tumultuous moment in the nation’s history.

Pen and ink portrait of a 19th century white man

Samuel Morton wasn’t a lone voice on the fringe of medicine.

‘Memoir of the life and scientific labors of Samuel George Morton’ by Henry S. Patterson, CC BY

Men of science and medicine

As a bioarchaeologist who has studied the Morton Collection for many years, I have sought to better understand the social, political and ideological circumstances that led to its creation. From my work – analyzing archival sources including letters, laws, maps and medical treatises, as well as the skulls themselves – I’ve learned that, over a lifetime, Morton fostered a professional network that had far-reaching tentacles.

He had plenty of help amassing the collection of skulls that bears his name.

The physician connected with medical colleagues – many of whom, like him, received degrees from the University of Pennsylvania – gentleman planters, enslavers, naturalists, amateur paleontologists, foreign diplomats and military officers. Occupational differences aside, they were mostly white, Christian men of some financial means.

Their interactions took place during a pivotal moment in American history, the interlude between the nation’s revolutionary consolidation and its violent civil unraveling.

Throughout this stretch of time, Morton and his colleagues catalyzed biomedical interventions and scientific standards to more effectively treat patients. They set in motion public health initiatives during epidemics. They established hospitals and medical schools. And they did so in the service of the nation.

Not all lives were seen as worthy of these men’s care, however. Men of science and medicine may have fostered life for many, but they also let others die. In “Becoming Object,” I track how they represented certain populations as biologically inferior; diseases were tied to nonwhite people, female anatomy was pathologized, and poverty was presumed inherited.

From person to specimen

Such representations made it easier for Morton and his colleagues to regulate these groups’ bodies, rationalize their deaths and collect their skulls with casual cruelty from almshouse dissecting tables, looted cemeteries and body-strewn battlefields. That is, a sizable portion of the skulls in Morton’s collections were not culled from ancient graves but belonged to those of the recently alive.

It is no coincidence that Morton began his scientific research in earnest the same year Andrew Jackson signed the Indian Removal Act of 1830. Men of science and medicine benefited from the expansionist policies, violent martial conflicts and Native displacement that underpinned Manifest Destiny.

line drawing of a skull from three angles, with text beneath about how it was collected from battle

A drawing from Morton’s book of the skull of a Seminole man killed by American troops. A bullet hole is visible on the left side of the man’s head.

‘Crania Americana’ by Samuel George Morton, CC BY

The collection reveals these acts of nation-building as necropolitical strategies – techniques used by sovereign powers to destroy or erase certain, often already vulnerable, populations from the national consciousness. These skulls attest to precarious existences, untimely deaths and trauma experienced from cradle to beyond the grave.

In the specific case of Native Americans, skeletal analysis testifies to the violent effects of U.S. military campaigns and forced removal. Native skulls that Morton labeled “warriors” have evidence of unhealed fractures and gunshot wounds. Children’s skulls bear the marks of compromised health; such pathology and their young ages at death are evidence of long-standing malnutrition, poverty and deprivation or stress.

To effectively transform subjects into objects – human beings into specimens – collected crania were ensconced in the institutional spaces of medical school lecture halls and museum storage cabinets.

There, Morton first numbered them sequentially. These numbers along with information about race, sex, age, “idiocy” or “criminality,” cranial capacity and provenance were inked on skulls and written in catalogs. Very rarely was the person’s name recorded. If used as teaching tools, Morton drilled holes to hang the skulls for display and notated them with the names of skeletal elements and features.

As dehumanizing as this process was, the Morton Collection does contain evidence of resilience and heterogeneous lives. There are traces of people with mixed-race backgrounds such as Black Indians. Several people may have also bent gender to navigate dire conditions or in keeping with social norms, such as native Beloved Women, who were active in warfare and political life.

stone monument in a graveyard

In contrast to those whose skulls ended up in his collection, Samuel Morton’s own grave was memorialized with a monument.

Pamela L. Geller

What these bones mean today

As anthropologists now recognize, it is through the repatriation of the remains of the people in the Morton Collection to their descendants, among other types of reparations, that current practitioners may begin to atone for the sins of intellectual forebears. Indeed, all institutions housing legacy collections must contend with this issue.

There are other, valuable lessons – about diversity and suffering – that the Morton Collection has to impart in today’s interesting times.

The collection demonstrates that the American body politic has always been a diverse one, despite efforts of erasure by men like Morton and his colleagues. Piecing together the stories of past, disenfranchised lives – and acknowledging the silences that have made it difficult to flesh them out – counters past white nationalism and xenophobia and their current resurgence.

The collection, I believe, also urges the repudiation of violence, casual cruelty and opportunism as admirable attributes of masculinity. Valorizing men who embody these qualities has never served America well. Particularly in the mid-1800s, when Morton amassed skulls, it led to a nation divided and hardened to suffering, an unfathomable death count and the increasing fragility of democracy.The Conversation

Pamela L. Geller, Associate Professor of Anthropology, University of Miami

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More

The post Hundreds of 19th-century skulls collected in the name of medical science tell a story of who mattered and who didn’t appeared first on theconversation.com

Continue Reading

The Conversation

Poor teacher training partly to blame for stalled engineering diversity goals

Published

on

theconversation.com – Lisa Bosman, Associate Professor of Industrial Engineering, Purdue University – 2024-11-14 07:22:00

Black students remain significantly underrepresented in engineering.
Tara Moore/DigitalVision via Getty Images

Lisa Bosman, Purdue University

Diversifying the science, technology, engineering and math fields has long been a top priority of many universities and tech companies. It’s also a goal of the National Science Foundation, the biggest funder of university-led research and development in the U.S.

But in the field of engineering, at least, there hasn’t been a lot of progress in diversifying the academic pipeline beyond white men.

The share of engineering bachelor’s degrees awarded to Black students has barely budged over the past decade. Women and Hispanic students fared better, but their respective percentages are still well below their shares of the population as a whole. The shares of engineering professors who are Black or Hispanic are also little changed and remain in the low single digits.

Many reasons have been cited for this lack of progress, including stereotypes, lack of exposure, limited role models and the recent backlash against so-called woke policies that emphasize diverse hiring policies. But, as a scholar of STEM education accessibility, I believe there’s another culprit: poorly prepared professors. Unlike the other challenges, it happens to be a much easier problem for universities themselves to remedy.

Some progress – but not a lot

A quick look at the numbers shows there hasn’t been much to show for all the efforts to improve diversity of the engineering field.

For example, in 2011, 4.2% of engineering bachelor’s degrees were awarded to African American students. A decade later, 4.7% of degrees went to African American students.

Progress was better for women and Hispanic students, but the numbers are still far from proportional to demographics. In 2011, Hispanic students earned 8.5% of engineering degrees. That rose to 13.6% in 2021 – versus the group’s 20% share of the U.S. population.

Women similarly saw gains over the years, going from 18% to 24%. But 6 percentage points in 10 years doesn’t look as good when you consider that women make up over half of the population.

The situation is worse when you look at the share who become professors. In 2020, 2.5% of engineering professors were African American, the same share as 10 years earlier. The share of Hispanic engineering professors edged up to 3.9% from 3.7%.

Women fared slightly better, rising to 18.6% from 13.8%, but as noted, that’s still a pretty poor result from all those efforts to diversity the academy.

More broadly, there’s a deeper problem in engineering schools. Just 56% of engineering students complete their bachelor’s degree in six years, according to a 2021 report by the American Society for Engineering Education. That compares with 64% for all fields. A National Science Foundation survey from the same year found that only 65% of science and engineering college graduates were working in a field related to their degree.

In other words, roughly a third of engineering students aren’t getting their degrees, and among those who do, around a third are switching careers – despite investing a lot of money on their education. While there’s limited data available on women or specific racial groups, I don’t think I’m going out on a limb to argue that the numbers for them look even worse.

Engineering teachers lack much teacher training

Among the reasons cited for this, I believe that the roles of teaching and learning haven’t received enough attention.

A growing body of research suggests that the quality of teaching needs to improve to reverse trends of lower graduation rates and properly teach an increasingly diverse student body. And I believe this is especially true in STEM disciplines like engineering.

Engineering professors commonly have training in advanced technical areas, but few receive training in teaching and learning. This challenge of poor teaching preparedness is not limited to the engineering discipline, but the consequences are much worse, especially given the push to diversify STEM.

Effective teaching enhances retention and completion rates by promoting better understanding of the material and creating more student involvement in the learning process. When students are actively engaged, supported and motivated to learn, they are more likely to persist and complete their educational goals.

Teacher training for universities is starkly different than K-12 training. Most school districts require that teachers have a four-year bachelor’s degree in teacher education. The focus is less on content and more on implementing effective teaching practices. K-12 training includes lesson planning, differentiated instruction and best practices for classroom management. There is also often a strong emphasis on social, emotional and behavioral well-being.

Although some engineering doctoral students might gain teaching exposure through a graduate teaching assistantship, this experience is commonly limited to grading assignments and rarely includes course design and development.

To teach as a professor in colleges and universities, most accreditation boards simply require a minimum of 18 graduate credits – or about two semesters – in the topic area. Here, the focus is strictly on research content. No prior teaching experience or training is required.

As a result, newly minted doctoral graduates are thrown into the lion’s den of teaching unprepared. If they are lucky, they are provided with the latest available syllabus. However, new professors are typically unprepared to accommodate students with disabilities, teach Black and Hispanic students, work with remedial students or navigate sensitive topics. They are generally anxious about teaching.

The field of K-12 teacher education has strategies to deal with these challenges. Continuing education and ongoing professional development keep both experienced and inexperienced teachers up to date on inclusive teaching practices. These can include sharing gender pronouns, ensuring media is accessible, using inclusive language and offering diverse perspectives in teaching resources. And yet, keeping up with these changes can be daunting for new professors.

children in classroom sit at desks with teacher standing in background
Some professors can learn a thing or two from K-12 teachers.
AP Photo/AJ Mast

Teaching teachers to teach

But there is a solution: treating college-level teaching as a professional development opportunity.

Most colleges and universities offer professional development training for professors and other instructors who want to opt in to teacher training, but the programs often have limited scope and responsibility at a level to make a substantial positive impact on student learning and engagement.

One way to change this is to invest in Scholarship of Teaching and Learning programs. This is a scholarly approach in which educators systematically study their teaching practices, student learning outcomes and the effectiveness of various teaching methods and strategies.

At Purdue University, we created a Scholarship of Teaching and Learning Accelerator program to help engineering graduate students around the world improve their teaching methods and share what they learned with others. In 2024, we published a peer-reviewed article that reports the process and what we learned.

By providing comprehensive professional development opportunities tailored to the needs of engineering instructors, institutions can support their ongoing growth and development as effective educators, ultimately enhancing the quality of engineering education and preparing students for success in their future career.

And in turn, better-trained teachers will be better equipped to support students from diverse backgrounds and help those traditionally underrepresented in STEM.The Conversation

Lisa Bosman, Associate Professor of Industrial Engineering, Purdue University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More

The post Poor teacher training partly to blame for stalled engineering diversity goals appeared first on theconversation.com

Continue Reading

The Conversation

Weight loss plans are less effective for many Black women − because existing ones often don’t meet their unique needs

Published

on

theconversation.com – Loneke Blackman Carr, Assistant Professor of Community and Public Health Nutrition, University of Connecticut – 2024-11-13 07:24:00

People who are obese or overweight are at higher risk of developing several chronic diseases.
andreswd/E+ via Getty Images

Loneke Blackman Carr, University of Connecticut and Jameta Nicole Barlow, George Washington University

The popularity of weight loss drugs such as Ozempic and Mounjaro continue to reflect Americans’ desire to slim down. While these new drugs have offered a solution for people struggling with obesity, many eligible patients – especially Black adults – cannot afford the high price.

These drugs are also not a one-stop solution for better health, as healthy eating and regular exercise are also key to losing weight. But current weight loss interventions based on lifestyle changes largely fail to meet the needs of Black women.

As community health researchers, we wondered why scientists have been unable to craft a lifestyle-based weight loss solution that works for Black women.

So we reviewed 10 years of research on weight loss interventions based on lifestyle changes. We found that only a few studies focused on Black women, and those that did often resulted in only small amounts of weight loss and were inconsistent in how they approached weight loss. Why is that?

Missing the mark for Black women

Obesity increases the risk of developing weight-related conditions such as Type 2 diabetes, heart disease and some types of cancer. Nearly 60% of Black women in the U.S. are obese, placing them at greater risk of developing these conditions.

Lifestyle interventions focusing on healthy diet and increased physical activity are proven to help most people lose weight, typically resulting in a 5% to 10% weight reduction that also reduces the risk of chronic disease. However, these lifestyle interventions usually result in only a 2% to 3% weight loss in Black women.

Our review suggests that lifestyle-based weight loss has been stymied among Black women because they often aren’t included in this research. Because their lived experiences aren’t considered in these studies, these interventions might not meet their specific needs. Of the 138 studies we assessed, Black women made up at least half of the participants in only eight studies.

Research on why lifestyle interventions are often less effective for Black women is lacking. However, some studies highlight the effects of race and gender on their daily lives as potential factors.

Person sitting on couch, pinching skin between eyebrows
The ‘strong’ Black woman is compelled to ignore her physical and emotional needs to take care of others.
PixelsEffect/E+ via Getty Images

The superwoman role

Black women exposed to the persistent stress of navigating everyday racism and sexism face the additional burden of what researchers call the superwoman role. Not only do Black women have to weather their own experiences of race- and gender-based inequalities, they’re also expected to be invulnerable, hyperindependent and suppress their emotions in order to seem strong to their family and community. Many minimize their vulnerabilities and overstress their capabilities in order to fulfill an overwhelming obligation to take care of other people.

Many famous names have spoken about the effects of being the strong superwoman. Actress Taraji P. Henson has pointed to how the need to display strength can lead to ignoring the physical and emotional needs of Black women.

Rapper Megan Thee Stallion spoke about the emotional toll of the superwoman role after being shot by rapper Tory Lanez. “As a Black woman … people expect me to take the punches, take the beating, take the lashings, and handle it with grace. But I’m human.”

The superwoman role levies a heavy tax on Black women, leaving little room to prioritize their health. To cope with the stress, some engage in emotional eating or binge eating. The constant demands of playing multiple caregiver roles can also disrupt physical activity.

Naturally, these challenges make it difficult to adopt healthier eating habits and a consistent exercise routine. Even when working toward weight loss, some Black women continue to gain weight.

Improving weight loss for Black women

Lifestyle interventions that fully integrate the lived experiences of Black women into treatment may be key to improving weight loss. We argue that Black Feminism and Womanism, which focus on the experiences of women of color, can guide researchers to rebuild and reframe weight loss interventions to be more effective for Black women.

Black Feminism and Womanism are approaches guiding Black women and girls to surviving and thriving, specifically by always considering the role that gender and race play in different issues. These frameworks focus on multiple areas of health and wellness, including physical, mental and emotional health, arguing that self-care and wellness practices are acts of social change.

Focusing on the full context of Black women’s lives can lead to better overall health. Obesity, specifically, is influenced by multiple factors, and treating obesity requires a focus on holistic health and well-being. This includes addressing Black women’s economic needs, incorporating faith practices central to Black life, attending to emotional and mental health, and building an environment that makes acquiring healthy food and engaging in daily exercise an easy choice.

Three people walking down a tree-lined trail, smiling at each other
Lifestyle changes are easier to incorporate when they’re tailored to your everyday life.
FG Trade/E+ via Getty Images

Current weight loss interventions vary widely in which elements of Black women’s lives they focus on. For example, some emphasize spirituality, while others concentrate on emotional health. Approaches to weight loss that respond to individual needs and move away from one-size-fits-all will be critical to addressing the various aspects of Black women’s lives that affect their wellness.

If health care providers and researchers begin listening to and working with Black women to redesign weight loss interventions, they will likely find that their efforts at addressing obesity among Black women are more effective.The Conversation

Loneke Blackman Carr, Assistant Professor of Community and Public Health Nutrition, University of Connecticut and Jameta Nicole Barlow, Associate Professor of Writing, Health Policy & Management and Women’s, Gender and Sexuality Studies,, George Washington University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More

The post Weight loss plans are less effective for many Black women − because existing ones often don’t meet their unique needs appeared first on theconversation.com

Continue Reading

Trending