On a cloudy afternoon on May 11, professors, students, parents, and children enjoyed the annual Science Rendezvous street festival at U of T’s St. George campus. The event let them celebrate and learn more about advancements and achievements in research.

The unifying theme of the festival this year was “S.T.E.A.M Big!”, which focused on the intersections between science, technology, engineering, art, and mathematics (STEAM). While art is often seen as separate from STEM disciplines, it is becoming increasingly common in the scientific community to encourage taking inspiration from the arts to drive innovative research.

Street stalls and displays exhibited the relationship between art and science

Displays that exemplified the relationship between art and science included outdoor music and dancing, as well as a visual art gallery inspired by math and science.

The focal points were the stalls and displays lining all of St. George Street. These exhibits presented some of the hottest topics and projects in science today, focusing on big interdisciplinary innovations found at the intersections of these rapidly advancing fields.

Over 80 faculties and community organizations set up exhibits. Highlights included displays of solar-powered cars, rockets, robots, and a wide array of other projects that would fascinate even those who have a passing interest in scientific inquiry.

This wide range and diversity of subjects represented by the participating volunteers brought the 2019 theme of STEAM to vibrant life.

Booths and demonstrations were highlights of the festival

The street festival included over 100 fascinating and interactive booths. Some leaned toward the classic science fair vibe, such as displaying glowing bacteria and allowing patrons to look through a solar telescope. Others opted to take a more creative approach, such as the station inviting attendees to paint with acids, bases, and plant juices.

Some displayed student innovations, such as the demonstration set up by U of T Blue Sky Solar Racing, an undergraduate team that designs, builds, and races solar powered vehicles. There was also a plethora of digital demonstrations interspersed between all the other projects, ranging from virtual reality tours of archeological sites to demos of the many student-made video games.

Street fairs like Science Rendezvous increase engagement with science

One of the goals of the festival was to raise interest in U of T’s science programs, as many high school students attended and participated in the event. An example was the molecular genetics-focused science fair that took place in Bahen Centre for Information Technology.

Besides attracting prospective students, the festival is intended to improve public involvement and investment in STEAM fields. From the number of students competing in the science fair, sporting U of T shirts with palpable excitement on their faces, to the sizeable crowds drawn in by the street festival, it is safe to say that both of these goals were achieved.

A rendezvous is a meeting or an appointment. In a way, St. George Street is a science rendezvous every day, with labs, classes, and seminars running regularly. What was special about this festival was that it took experiences that are often inaccessible and presented them in a way that could appeal to all.

The pretension and exclusivity that often seems to follow research was stripped away, and all that was left was mystery, excitement, and curiosity. This contributed to why the event drew in hundreds of people, and why volunteers and attendees come back year after year.

During sperm transfer and climax, the male redback spider does a somersault of sorts, placing his abdomen in the perfect position for the female to eat, and more often than not, she goes for it.

Whether you think it romantic or horrific, there is something captivating about this ultimate sacrifice during the moment of climax. But because of this, the female redback may remain a lonely single after sex, albeit a little less hungry.

Black widows are also members of the Latrodectus genus to which redbacks belong.

This act of sexual sacrifice, called ‘terminal investment,’ has been extensively studied by the lab of Dr. Maydianne Andrade at UTSC, where thousands of black widows — notorious for their highly potent and neurotoxic venom — share refuge.

However, if you think it romantic, perhaps the male spider’s reasoning for sacrifice may make you think again. It appears that the male redback’s terminal investment serves an evolutionary, or depending on how you look at it, selfish purpose.

Though it may seem counterproductive for a male spider to sacrifice his entire existence for just a single shot at producing progeny, there are several adaptive advantages that he gains by taking this risk.

Self-sacrifice serves to enhance male paternity both by increasing the number of eggs the male spider fertilizes and by decreasing the chance that their female partner will mate with another competitor.

Andrade’s team found that six out of nine females that cannibalized their partners refused to mate with a second male, while only one in 23 females that didn’t have the pleasure of consuming their mates did the same.

Also, the chance that the male could mate again if he escapes the fangs of his lover is meagre. Therefore, his self-sacrifice offers a way to give it all he’s got by partaking in the ultimate act of evolutionary fitness.

Though female redbacks can be violent in their courtship, they do offer some mercy to the fittest of their male counterparts.

‘Premature cannibalism’ — which occurs before copulation is complete — is much less common if the male offers courtship for over 100 minutes, a marathon of sorts for the reward of paternity. However, males that are ready for this marathon must be wary of cheating competitors that can sneak in at the finish line, disguise themselves as the winner, and avoid being prematurely eaten.

And when it comes to being eaten by their mate, size does matter. Females are less likely to prematurely cannibalize a large marathon runner than a small sprinter.

However, more importantly, a male is less likely to be eaten by his female counterpart if she is well-fed — he only offers a meal sized at one or two per cent of her body mass.

Unfortunately for him, food is typically a rare commodity for a plump female redback in her native Australian habitat, so she may well take the meal that he offers in addition to her potential future offspring.

While this extreme sacrificial gesture and its violent ending could be seen as a spider’s ultimate Valentine’s Day gift, in the end, it is neither the life of the female nor the male redback that is rewarded, but their offspring that ultimately earn the gift of life — and go on to do the same.

A recent study conducted by PhD candidate David Timerman and Professor Spencer Barrett in the Department of Ecology and Evolutionary Biology sought to understand the transition from insect pollination to wind pollination in angiosperms, or flowering plants.

A 2002 paper reported that although most flowering species enable insect pollination, around 18 per cent of angiosperms use wind pollination. These transitions are thought to occur when changes to the environment cause a reduction in the number of available insect pollinators. The two forms of pollination differ in their pollen dispersal method as well as the characteristics of their stamens, or pollen-producing organs.

Timerman and Barrett’s research explains the underlying mechanism behind this transition.

In environments characterized by the absence of insect pollinators, a lower natural frequency of stamens is favoured for wind pollination, which becomes essential to reproduction. The researchers linked this lower frequency to an increased release of pollen. These outcomes have important implications for the current understanding of the prevalence and evolution of wind pollination and the role of stamen as a direct mediator of pollen dispersal.

These findings could also help researchers understand how climate change — an agent responsible for the pollinator crisis — could affect this transition in future generations.

Timerman and Barrett examined wind-induced pollen release in Thalictrum pubescens, also known as the king of the meadow, which uses both insect and wind pollination.

They speculated that this species may be currently undergoing the insect- to wind-based pollination transition, and could be used to measure important changes in the early stages of the evolution.

Using a custom-built wind tunnel, Timerman placed individual flowers onto a vibrating table and exposed them to a fixed interval of wind. He then recorded videos of the motion of the stamens in the wind tunnel, and measured the dispersal of pollen onto a sticky microscope slide down-wind from the flowers.

“The videos permitted me to determine the vibration frequency of stamens and their acceleration in wind which I then related to pollen release,” Timerman wrote in an email to The Varsity.

When the stamens’ natural frequency was lower, there was an increase in pollen release. However, this advantage was limited to the absence of pollinators. When pollinators were present, the increased pollen release and fitness of a lower stamen frequency was not observed.

Likewise, in the absence of pollinators, female plants that were paired with males which had low stamen natural frequencies produced a higher proportion of seed. This effect was not seen when pollinators were available.

Timerman and Barrett’s findings highlight the important fitness consequences along the evolution from insect to wind pollination. Without the availability of pollinators, plants may evolve lower stamen natural frequencies that optimize pollen dispersal in wind.

Over time, wind-pollinated lineages lose traits such as showy petals and fragrances that attract insects, but become structurally optimized for pollen transport in air streams.

“My research shows that the stamens have evolved to harness wind energy causing stamens to vibrate and release pollen efficiently,” wrote Timerman.

Currently, Timerman is working on a project that compares pollen release biomechanics across different wind and insect pollinated species of the Thalictrum genus.

“I am interested in this genus because wind pollination has evolved from insect pollination independently on several occasions,” he explained. “Each of these transitions represents an independent evolutionary experiment, thus providing the replication needed to determine whether a reduction in stamen natural frequency is consistently associated with or driving transitions from insect to wind pollination.”

Editor’s Note: This article’s previous headline incorrectly described flowering plants as insect pollinators.

What’s in a word?

In the scientific community, the word ‘retraction’ carries with it a pervasive stigma, often conflated with the idea of an academic death penalty. Retractions, or the pulling of a paper from publication, can tarnish a researcher’s reputation, call into question the legitimacy of a lifetime of work, and dismantle careers.

Outside of the personal realm, retractions alter public perceptions of science.

Last month, the Retraction Watch blog released a Retraction Watch Database. The database is a comprehensive list of retractions in scientific journals since 1923. Out of the 18,000 retractions and notes available on the database, 63 are affiliated with U of T.

What constitutes a retraction?

Science prides itself on being self-correcting, and retractions are a powerful mechanism for that self-correction.

When errors are relatively minor and restricted to a small portion of a publication, a complete withdrawal of the scientific finding is unnecessary and a correction may be issued.

The World Association of Medical Editors defines scientific misconduct as including the falsification, distortion, and omission of data; failure to report misconduct; and the destruction of information relevant to a publication.

Retractions are issued to correct the scientific literature and alert readers of the unreliable conclusions of a paper. According to the Committee on Publication Ethics (COPE), they are “[not] to punish authors who misbehave.”

Yet intent and outcome are not always synchronous. The closure of Toronto-based researchers Dr. Sylvia Asa’s and Dr. Shereen Ezzat’s labs, and the termination of their positions within the University Health Network (UHN), is evidence of how retractions can pose dire consequences to academics’ careers.

Retraction guidelines are inconsistent and could be misinterpreted

Husband-wife duo Asa and Ezzat account for four of U of T’s retractions listed on the Retraction Watch Database. Asa and Ezzat’s cases of scientific misconduct made headlines in the Toronto Star in 2015 and 2016.

They were found responsible for scientific misconduct in the form of material non-compliance. They failed, as principal investigators, to disclose alterations to images and provide preliminary data that matched the published ones in a number of cases of published work.

Asa lost her position as the head of UHN’s Laboratory Medicine Program, the largest program of its kind in Canada, and the UHN imposed sanctions against Asa and Ezzat.

Regarding her 2002 paper, which was one of her articles that was later retracted, Asa told The Varsity that “this was a paper that was almost five years of work. Most of my research starts with a clinical problem, and one of the things I’ve studied is pituitary [tumours].”

“[UHN] claim that two images [of the electrophoresis gels] came from the same one and had been manipulated,” said Asa. “The fact is that we had all the raw data, we had all the original data.”

“Nothing changes anything in that paper, based on the fact that the image was wrong. Patients who have pituitary tumours, for all the people who were involved in the research, all the work that we did is still true,” said Asa. “The results of that paper are no different today.”

The journals in which Asa published her findings were alerted to the irregularities in her research via an outside source.

UHN opened an investigation into Asa’s publications as a result of these allegations, and implicated the pathobiologist in the fabrication and falsification of images. These allegations were challenged in court by Asa and Ezzat, where it was ultimately found that they could not prove who tampered with the images, based on the evidence.

Asa told The Varsity that she felt targeted by the retraction process.

“The retraction process is interesting. It’s definitely necessary. But it has limitations… There have been mechanisms put in place in a lot of different parts of the world, to be more objective and have more standardized criteria for how an investigation is done,” said Asa.

But in a case almost identical to Asa’s, a Montréal researcher was given the opportunity to issue a correction instead of having to retract the entire article.

Cases like this demonstrate the wildly different implementation of retraction guidelines across institutions.

An article in Science suggested that this may be because it is ultimately up to the editors and institutions to determine whether the paper is withdrawn, as COPE only provides guidelines to clarify when a paper should be retracted.

In addition, a study in BMJ Open revealed that retraction notices did not adhere to COPE guidelines in BioMed Central journals. In 11 per cent of retracted articles, the reason for retraction was unclear — six per cent did not state who was retracting the article, while four per cent were retracted simply because not all authors were aware of the paper submission.

The stigma around retractions

A common misconception is that a retraction is invariably associated with data fabrication or scientific misconduct. Yet, of the 63 U of T affiliated papers listed on the Retraction Watch database, only seven are listed for misconduct and eight are listed for fabrication. Fourteen publications have been retracted due to errors in data, attributed to honest error.

Dr. Peter Jüni, Director of the Applied Health Research Centre at St. Michael’s Hospital and professor in the Department of Medicine, has co-authored such a paper.

The publication, a network meta-analysis on the effectiveness of nonsteroidal anti-inflammatory drugs for treating osteoarthritis, was published in March 2017 and retracted in July 2017.

A network meta-analysis compares multiple treatment interventions for a condition directly, using existing comparisons of the interventions in published trials, and indirectly, across different trials.

According to Jüni, research assistants in his team had unknowingly incorporated a duplicate article that had “slightly different results extracted twice” to build their meta-analysis.

“The authors published twice, but they didn’t make it clear that these are the results describing the same population with light differences,” said Jüni. “My colleagues decided to re-run the analysis… and eliminate the duplicate article and… add two new articles that were brought up by colleagues.”

“Now if you include all of those… in an integrated analysis… your numbers will change very slightly,” explained Jüni. “The conclusions of the paper didn’t change at all.”

Jüni recognized the duplicated paper, and the authors were alerted to the two missed trials via colleagues in Ottawa.

Although the error was minimal in nature, The Lancet and the authors agreed it was more feasible to retract and republish the article, as the error ran through different parts of the results and several portions of the paper.

Jüni recognized a flaw in the retraction process that could be exacerbated by the associated stigma of retraction.

“If this is not indexed properly, which was happening at the beginning — the National Library of Medicine just pointed to the retracted article, but it was not clear in PubMed or Medline that this was basically paired with a republication — then it could mean potential questions regarding your reputation,” said Jüni. “The question is then, should we call it differently?”

“Would I prefer to have another label associated with it? Yes, because of the associated stigma — but I don’t think it will happen and I think the important part is that the indexing system changes their way of reporting it. It’s not optimal, but honestly, I can live with it. And obviously I have to live with it,” continued Jüni.

Despite the sting of retractions and the potential fallout, Jüni believes that researchers have an obligation to self-report mistakes.

“You need to live as a leader, in a culture where everybody admits [they don’t] know or [made] a mistake. I need to start with that as the Director of Applied Health Research — if I don’t live it, my people don’t dare admit mistakes. We need that to make research better. That’s part of the quality assurance process.”

It is clear that the retraction process is flawed — it holds too much stigma, does not implement guidelines consistently, and fails on many occasions to communicate to the public the reasons for paper withdrawal. However, it is currently the only system we have to correct the literature and protect scientific endeavours.

What implications do retractions have for scientific research?

Trudo Lemmens, professor and chair of the Department of Health Law and Policy at the Faculty of Law, believes that the increase in the number of retractions may be due to a growing concern around scientific integrity due to a growth in scientific publications over the years.

Science reports that an increase in retractions could be attributed to more comprehensive oversight from scientific journals. Though editorial practices differ from journal to journal, a rise in retractions hints at stricter editorial practices.

In 2009, COPE published guidelines that suggest a publication should be retracted if the findings are unreliable due to scientific misconduct, plagiarism, duplication, or honest error. By 2015, these guidelines were adopted by two-thirds of 147 high-impact journals, and have helped standardize the retraction process.

Editor’s Note (November 27): A previous version of this article incorrectly suggested that Jüni’s assistants were the ones to discover the duplicate.

Government-sponsored screening for breast and ovarian cancer in Canada can take up to a year to occur and can be denied based on a patient’s risk profile. To shorten wait times and offer universal testing, the Familial Breast Cancer Research Unit at Women’s College Hospital (WCH) has introduced The Screen Project initiative, which aims to make screening universally accessible to patients over 18 in Canada, and hopefully produce better patient outcomes.

The Screen Project has discounted its regular screening price to $99 USD for October, which is Breast Cancer Awareness Month. Ordinarily, the research unit screens patients for $165 USD. Results are expected within two to four weeks.

Why isn’t government-funded screening universal?

According to Dr. Steven Narod, Director of the Familial Breast Cancer Research Unit at WCH, screening through Canada’s universal healthcare system costs around $2,000–3,000 and wait times can last up to one year. As a result, as little as three per cent of women are eligible for the test per year.

But in 2017, the Familial Breast Cancer Research Unit found that commercial genetic testing could be completed in a shorter amount of time and for a fraction of the cost by sending samples to Veritas Genetics, an American genetic sequencing laboratory with whom the Unit has partnered for The Screen Project.

Veritas Genetics tests for BRCA1 and BRCA2, which are gene mutations associated with breast cancer. Women with a BRCA mutation have up to an 80 per cent lifetime risk of breast cancer and a 40 per cent lifetime risk of ovarian cancer versus a 12 per cent and a 1.3 per cent lifetime risk for women without the mutation, respectively.

How does the project work?

To provide a genetic sample for testing, patients order a genetic test kit from Veritas Genetics, provide a saliva sample, and then ship the kit and sample back to the Veritas Genetics lab. The lab tests the sample and releases the results to the patient and the Familial Breast Cancer Research Unit.

Patients with a negative test result receive an email or letter of notification. But patients who produce a positive test result receive an email or letter, as well as a personal phone call from a genetic counsellor at the Familial Breast Cancer Research Unit.

According to Narod, The Screen Project’s offer of “genetic testing for breast and genetic testing for ovarian cancer” for $165 USD is “ethical and wise,” since it is affordable for most Canadians.

However, Narod notes that the results of The Screen Project raise an ethical concern of whether it is “proper, right, and ethical to offer healthcare services outside of what’s insured by the public healthcare system.”

As The Screen Project continues, Narod plans to track the interest in genetic testing for breast and ovarian cancer in Canada, patient satisfaction afterward, and the actions that the project and patients choose to take to reduce their risk of breast and ovarian cancer following a positive test result.

For female North American dance flies, size definitely matters.

A recent UTM study discovered that, for North American male dance flies, sexual attraction is highest when female mates display large inflatable abdominal sacs. 

The study was published in Proceedings of the Royal Society B by UTM postdoctoral fellow Rosalind Murray, UTM biology professor Darryl Gwynne, U of T biology lecturer Jill Wheeler, and University of Stirling biologist Luc Bussiere.

To attract male dance flies for fertilization, the researchers found that female flies display signs of sexual ornamentation. The female flies use valuable energy reservoirs to expand their abdominal sacs, which is appealing to their male counterparts. 

In cases where female dance flies have smaller abdominal sacs, they attract males flies through larger leg scales.  

When discussing the reasoning behind her study, Murray said she “wanted to do an experiment to see if these ornaments were actually attracting the males and if they were working in the same way we typically see male ornaments — so, bigger is better.”

Why are the female flies using large amounts of energy to attract their male counterparts? 

According to Murray, the male flies provide them with a “food gift,” because the female flies have lost their ability to hunt, “so the males go hunting and they bring, usually another fly or insect. They kill it and they present it to the female in exchange for mating.”

The research took place over a 10-day period on an island in Credit River last June. North American dance flies are peculiar creatures that only appear for one hour at dawn and another hour at dusk.

As such, to complete the field research, Murray would wake up before sunrise to study the flies for an hour when they came out.  

During the day, Murray would analyze the data collected from the morning, and then she would venture out again at 8:30 pm to study the flies until sundown.

To test her theory, Murray created models that imitate female shapes and examined the impact of the two ornament types.

The research is particularly significant because it demonstrates a stark shift in our understanding of the animal kingdom. 

Typically, research has suggested that male animals use their energy to attract female counterparts. Much of Charles Darwin’s research, for example, focused on this phenomenon of sexual selection between mates.

However, Murray and Gwynne’s research turns this idea on its head.

“There are certain ways across animal kingdoms that males and females behave… It’s rare that you do find the vice versa, whereas in these flies, the subject of the paper, females are displaying very male-like traits,” Gwynne said. “They have reversed roles.”

Within the field of evolutionary biology, Murray’s study is the first that demonstrates this kind of female sexual ornamentation. “It’s such a bizarre system,” Murray said. 

“We’re looking at similar questions among many species of dance flies, thinking about how different species have evolved these ornaments.” 

— With files from Srivindhya Kolluru

It was recently announced that U of T will implement 49 new recommendations from the Equity and Diversity in Research and Innovation Working Group to foster more equity in every stage of research and academia — from ensuring diversity in committees that provide awards and funding to requiring further training in unconscious biases.

This is certainly exciting, especially since the announcement comes with concrete steps to fulfill its vision, which makes this promise feel substantive rather than empty. Assuming that these measures are put into place and followed, real progress is on the horizon.

Sadly, this change is urgently needed in academia. Study after study has shown that the field not only consists of overwhelming numbers of white and male academics, but it is also reluctant to change itself.

For example, in a 2012 study, professors in biology, chemistry, and physics departments at six universities across the US were given identical applications for a lab manager position, with some applicants using female names and others using male names. The male applicants were rated as more “hireable” and competent, and offered a larger starting salary.

In 2016, the Dean of U of T’s Faculty of Medicine, Dr. Trevor Young, revealed some sobering statistics about the racial and socioeconomic makeup of medical students and faculty: Black, Filipino, Latinx, and Indigenous students were “woefully under-represented,” and, in 2013, 75 per cent of the faculty were white.

To even produce these statistics is surprisingly difficult. In 2017, CBC reported that despite the claims of many Canadian universities as pro-diversity, very few actually have any data about the racial demographics of their students. This allows universities to plead ignorance about any kind of discrimination on their part, and allows them to continue a charade of racial blindness.

Many may fight back against these measures as being ‘discriminatory’ toward white men in favour of minorities and underprivileged folks, or suggest that the best solution would simply be to approach hiring, funding, and the like with blindness toward gender and racial considerations. To the former point, it is worth noting that none of the recommendations even suggest or imply discrimination toward white men.

To the latter point, I would say that this is impossible thanks to unconscious biases, which means that even those with the best of intentions still discriminate. In the 2012 study, it is highly unlikely that the faculty involved all held genuine contempt for women, but it is far more likely that they had absorbed societal ideas about men and women in science, and reflected them in hiring practices.

To go beyond the simple fact that more people of diverse backgrounds should have opportunities in academia and research, it should be noted that the type of research that would be conducted with more people who are not white men could be badly needed, or done with a genuine cultural sensitivity that may not be present otherwise.

A person with a particular racial background may have an interest in a research topic that affects them more than it does the dominant race. Someone who is part of an underprivileged community, especially one that has a history of mistreatment in research, may be able to connect with their own community and understand how to conduct research with them better.

Research in every field, from medicine to anthropology, has a tainted history of ignoring the needs and wishes of the communities they encounter, which can lead to dark consequences. Look no further than eugenics as a field, the Tuskegee syphilis experiments, or the US Army working closely with anthropologists to finetune their strategy in Afghanistan.

Paula Rochon, Vice-President of Research at Women’s College Hospital, was part of the working group and reported last yearthat, because women were underused as research subjects in a study on dementia, it is unknown how certain dementia medications affect women, despite the fact that most elderly people with dementia are women. More female researchers, in that case, would have been more likely to push for more female subjects.

And we can extrapolate that to a larger scale. If most researchers are white men, with funding being granted by other white men, and the findings are presented to white men with nobody else in the room, the research would suffer by only focusing on certain issues and their effects on certain people.

No matter your personal identity, I hope that advocating for equity and diversity in academia and research is something we can all celebrate. These steps get more people from diverse backgrounds to be a part of every step of the process. This means more opportunities for more people, better research, and positive outcomes for everyone.

Adina Heisler is a fourth-year Women and Gender Studies and English student at University College.

A single bone fragment can reveal thousands of years of human history.

In a study published in Nature, a team of researchers, including U of T Professor Bence Viola, identified a hybrid between two extinct lineages of hominids — Neanderthals and Denisovans — in a bone fragment.

Neanderthals lived on earth about 40,000 years ago, and, along with modern humans, they evolved from Homo erectus. Denisovans diverged from Neanderthals, but little is known about them other than bits of information recovered from bone fragments of their extremities, found in a Denisova Cave in Siberia’s Altai Mountains.

This is why, when researchers found a bone fragment in the Denisova Cave in 2012, they didn’t give much thought to the finding; it looked like all the others, an ordinary and tiny piece of what was thought to be part of a bear or lion.

After all, when a site is being excavated, many items are found, including pieces from animals and insects.

“There are 100,000 bone fragments found at a time and this particular one had a length of only 2.5 centimetres long, roughly the size of a toe bone,” said Viola.

A few years following the discovery, the fragments were analyzed for collagen. Finding a long bone fragment gave researchers an advantage for conducting DNA extraction techniques because of its morphology; it preserves better and allows for further manipulation.

“The bone was also discovered to have an acid coating which suggested it was digested by hyenas,” added Viola. The fact that DNA evidence survived this process makes this discovery even more extraordinary.

The bone was determined to belong to a female around age 13. This teenager died 90,000 years ago and was the offspring of a Neanderthal mother and Denisovan father.

Viola couldn’t believe it.

Based on previous studies, it was assumed that Neanderthals and Denisovans occasionally interacted, but interbreeding between the two hominins was thought to be rare.

This breakthrough informs researchers that interbreeding could have contributed to the gene flow, or transfer of genetic information, and it is now evident in the bone fragment.

The fragment is also evidence that the two species were in the same region at the same time.

Interbreeding is a result of various factors, such as an attempt to colonize certain areas. The discovery could help shape our understanding of hominin interactions and forms the basis to determine further benefits to interbreeding.

As such, this finding allows researchers to try and understand the lives of our closest ancient human relatives.