The findings are reported in Psychological Science, a journal of the Association for Psychological Science. Across a series of studies involving healthy and sick adults, 75% of the 4,110 participants said they had either hidden an infectious illness from others at least once or might do so in the future. Many participants reported boarding planes, going on dates, and engaging in other social interactions while secretly sick. More than 61% of healthcare workers participating in the study also said they had concealed an infectious illness.

Interestingly, the researchers found a difference between how people believe they would act when ill and how they actually behave, said Wilson N. Merrell, a doctoral candidate and lead author on the study.

“Healthy people forecasted that they would be unlikely to hide harmful illnesses — those that spread easily and have severe symptoms — but actively sick people reported high levels of concealment regardless of how harmful their illness was to others,” Merrell said.

In the first study, Merrell and his colleagues — psychology professor Joshua M. Ackerman and PhD student Soyeon Choi — recruited 399 university healthcare employees and 505 students. The participants reported the number of days they felt symptoms of an infectious illness, starting in March 2020, when the COVID-19 pandemic began. They then rated how often they actively covered up symptoms from others, came to campus or work without telling others they were feeling ill, or falsified mandatory symptom screeners that the university had required for anyone using campus facilities.

More than 70% of the participants reported covering up their symptoms. Many said they hid their illness because it would conflict with social plans, while a small percentage of participants cited pressure from institutional policies (e.g., lack of paid time off). Only five participants reported hiding a COVID-19 infection.

In a second study, the researchers recruited 946 participants online and randomly assigned them to one of nine conditions in which they imagined being either moderately or severely sick while in a social situation. In each condition, the risk of spreading the illness was designated as low, medium, or high. (To control for the special stigma associated with COVID-19 at the time, the researchers asked participants not to imagine being sick with that disease.) Participants were most likely to envision themselves hiding their sickness when symptom severity was low, and least likely to conceal when symptoms were severe and highly communicable.

In another study, Merrell and colleagues used an online research tool to recruit 900 people —

including some who were actively sick — and asked them to rate the transmissibility of their real or imagined illness. The participants were also asked to rate their likelihood of covering up an illness in a hypothetical meeting with another person.

Results showed that compared to healthy participants who only imagined being sick, those who were actively ill were more likely to conceal their illness regardless of its transmissibility.

“This suggests that sick people and healthy people evaluate the consequences of concealment in different ways,” Merrell said, “with sick people being relatively insensitive to how spreadable and severe their illness may be for others.”

The COVID-19 crisis may have shaped the way the participants thought about concealing an illness, Merrell said, adding that future research could explore how ecological factors (e.g., pandemics) and medical advances such as vaccines influence people’s disease-related behavior. The research team is also expanding this line of investigation to other countries to uncover potential cultural differences in concealment behaviors, he said.

Overall, the findings carry significant public health implications, illuminating the motivations and tradeoffs we make in social interactions when we’re sick, Merrell added.

“After all, people tend to react negatively to, find less attractive, and steer clear of people who are sick with infectious illness,” he said. “It therefore makes sense that we may take steps to cover up our sickness in social situations. This suggests that solutions to the problem of disease concealment may need to rely on more than just individual good will.”

While scientists have long been intrigued by the question of how humans’ bipedal stance and movement evolved from a quadrupedal ancestor, neither past studies nor fossil records have permitted the reconstruction of a clear and definitive history of the early evolutionary stages that led to human bipedalism.

However, a new study, which centers on recently discovered evidence from skulls of a 6-million-year-old fossil ape, Lufengpithecus, offers important clues about the origins of bipedal locomotion courtesy of a novel method: analyzing its bony inner ear region using three-dimensional CT-scanning.

“The semicircular canals, located in the skull between our brains and the external ear, are critical to providing our sense of balance and position when we move, and they provide a fundamental component of our locomotion that most people are probably unaware of,” explains Yinan Zhang, a doctoral student at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences (IVPP) and the lead author of the paper, which appears in the journal the Innovation. “The size and shape of the semicircular canals correlate with how mammals, including apes and humans, move around their environment. Using modern imaging technologies, we were able to visualize the internal structure of fossil skulls and study the anatomical details of the semicircular canals to reveal how extinct mammals moved.”

“Our study points to a three-step evolution of human bipedalism,” adds Terry Harrison, a New York University anthropologist and one of the paper’s co-authors. “First, the earliest apes moved in the trees in a style that was most similar to aspects of the way that gibbons in Asia do today. Second, the last common ancestor of apes and humans was similar in its locomotor repertoire to Lufengpithecus, using a combination of climbing and clambering, forelimb suspension, arboreal bipedalism, and terrestrial quadrupedalism. It is from this broad ancestral locomotor repertoire that human bipedalism evolved.”

Most studies of the evolution of ape locomotion had focused on comparisons of the bones of the limbs, shoulders, pelvis, and spine and the way they are associated with the different types of locomotor behaviors seen in living apes and humans. However, the diversity of locomotor behaviors in living apes and the incompleteness of the fossil record have hampered the development of a clear picture of human bipedalism’s origins.

The skulls of Lufengpithecus — originally discovered in China’s Yunnan Province in the early 1980s — have given scientists the opportunity to address, in new ways, unanswered questions about the evolution of locomotion. However, the heavy compression and distortion of the skulls obscured the bony ear region and led previous researchers to believe that the delicate semicircular canals were not preserved.

To better explore this region, Zhang, Ni and Harrison, along with other researchers at IVPP and the Yunnan Institute of Cultural Relics and Archaeology (YICRA), used three dimensional scanning technologies to illuminate these portions of the skulls to create a virtual reconstruction of the inner ear’s bony canals. They then compared these scans to those collected from other living and fossil apes and humans from Asia, Europe, and Africa.

“Our analyses show that early apes shared a locomotor repertoire that was ancestral to human bipedalism,” explains IVPP Professor Xijun Ni, who led the project. “It appears that the inner ear provides a unique record of the evolutionary history of ape locomotion that offers an invaluable alternative to the study of the postcranial skeleton.”

“Most fossil apes and their inferred ancestors are intermediate in locomotor mode between gibbons and African apes,” adds Ni. “Later, the human lineage diverged from the great apes with the acquisition of bipedalism, as seen in Australopithecus, an early human relative from Africa.”

By studying the rate of evolutionary change in the bony labyrinth, the international team proposed that climate change may have been an important environmental catalyst in promoting the locomotor diversification of apes and humans.

“Cooler global temperatures, associated with the build up of glacial ice sheets in the northern hemisphere approximately 3.2 million years ago, correspond with an uptick in the rate of change of the bony labyrinth and this may signal a rapid increase in the pace of ape and human locomotor evolution,” explains Harrison.

Last summer, archaeologists from Gothenburg University and Kiel University excavated a dolmen, a stone burial chamber, in Tiarp near Falköping in Sweden. The archaeologists judge that the grave has remained untouched since the Stone Age. However, the odd thing is that parts of the skeletons of the people buried are missing.

Skulls and large bones are missing and may have been removed from the grave. We don’t know whether that has to do with burial rituals or what’s behind it,” says Karl-Göran Sjögren.

Now that the researchers have examined the material from the grave, they have found that it contains bones from hands and feet, fragments of rib bones and teeth. But skulls and larger bones such as thigh and arm bones are very few.

“This differs from what we usually see in megalith graves, i.e. stone burial chambers from the Neolithic period,” Karl-Göran Sjögren explains. “Usually, the bones that are missing are smaller bones from feet and hands.”

Torbjörn Ahlström, Professor of Osteology at Lund University, studied the bone finds. His conclusion is that the bones come from at least twelve people, including infants and the elderly. But the archaeologists don’t yet know why they died.

“We haven’t seen any injuries on the people buried so we don’t think violence is involved. But we are continuing to study their DNA and that will show whether they had any diseases,” says Karl-Göran Sjögren.

Falköping has long been known for its many passage graves dating from a somewhat later period, approximately 3300 BCE. Agriculture reached Falbygden in about 4000 BCE, i.e. about 500 years before the grave in Tiarp was built. In all likelihood, the people buried in the dolmen were farmers.

“They lived by growing grain and keeping animals and they consumed dairy products,” says Karl-Göran Sjögren.

Are the people buried in the grave related?

A number of samples were taken at the excavation last summer, including DNA from the skeletal remains.

“The preliminary DNA results show that the DNA in the bones is well preserved. This means we will be able to reconstruct the family relationships between the people in the grave and we are working on that now,” says Karl-Göran Sjögren.

Falbygden is known for its many traces of people from the Stone Age. There are more than 250 passage graves here, large graves built of blocks of stone.

“But this dolmen is older. It’s about 200 to 150 years older than the passage graves, making it one of the oldest stone burial chambers in Sweden and across the whole of Scandinavia,” says Karl-Göran Sjögren.

There is another thing that makes the grave unique.

“It’s the way it is constructed. There’s a little niche at each end. This is unique for graves in Falbygden,” says Karl-Göran Sjögren.

The study is freely available as open access in Journal of Neolithic Archaeology. Tiarp Backgården. An Early Neolithic Dolmen in Falbygden, Sweden and Early Megalithic Tombs in South Scandinavia and Northern Central Europe.

Facts

• The grave in Tiarp Backgården in Falköping, was first found in 1929. It was studied by archaeologists at the time, and then again in 2014, which was when it was discovered that the grave was more or less intact and had bodies buried inside it.

• The archaeological excavation in Tiarp in summer 2023 was carried out jointly by Gothenburg and Kiel Universities.

• Study participants Karl-Göran Sjögren, Malou Blank and Tony Axelsson, Department of Historical Studies, Gothenburg University. Torbjörn Ahlström, Lund University Stefan Dreibrodt, Institute for Ecosystem Research, Kiel University Johannes Müller, Institute of Prehistoric and Protohistoric Archaeology, Kiel University.

Wildlife filmmaker Carlos Gauna and UC Riverside biology doctoral student Phillip Sternes were scanning the waters for sharks on July 9, 2023, near Santa Barbara on California’s central coast. That day, something exciting appeared on the viewfinder of Gauna’s drone camera. It was a shark pup unlike any they’d ever seen.

Great whites, referred to only as white sharks by scientists, are gray on top and white on the bottom. But this roughly 5-foot-long shark was pure white.

“We enlarged the images, put them in slow motion, and realized the white layer was being shed from the body as it was swimming,” Sternes said. “I believe it was a newborn white shark shedding its embryonic layer.”

These observations are documented in a new paper in the Environmental Biology of Fishes journal. The paper also details the significance of having seen a live newborn white shark.

Gauna is known online as The Malibu Artist. He has spent thousands of hours filming sharks around the world, and his videos of them swimming close to beachgoers have millions of views. What he and Sternes observed could help solve the longstanding mystery of great white birthing habits.

“Where white sharks give birth is one of the holy grails of shark science. No one has ever been able to pinpoint where they are born, nor has anyone seen a newborn baby shark alive,” Gauna said. “There have been dead white sharks found inside deceased pregnant mothers. But nothing like this.”

Though the paper authors acknowledge it is possible the white film the shark shed could have been a skin condition, the duo do not believe this to be the case. “If that is what we saw, then that too is monumental because no such condition has ever been reported for these sharks,” Gauna said.

For many reasons, the duo believes what they saw was in fact a newborn great white.

First, great white females give birth to live pups. While in utero, the embryonic sharks might feed on unfertilized eggs for protein. The mothers offer additional nourishment to the growing shark pups with a ‘milk’ secreted in the uterus.

“I believe what we saw was the baby shedding the intrauterine milk,” Sternes said.

A second reason is the presence of large, likely pregnant great whites in this location. Gauna had observed them here in previous years, and in the weeks leading up to the observation. “I filmed three very large sharks that appeared pregnant at this specific location in the days prior. On this day, one of them dove down, and not long afterwards, this fully white shark appears,” Gauna said. “It’s not a stretch to deduce where the baby came from.”

Thirdly, the shark’s size and shape are also indicative of a newborn. What the two observed was thin, short, and rounded. “In my opinion, this one was likely hours, maybe one day old at most,” Sternes said.

Finally, this location off the coast of central California has long been proposed as a birthing location for great whites. “There are a lot of hypothetical areas, but despite intense interest in these sharks, no one’s seen a birth or a newborn pup in the wild,” Sternes said. “This may well be the first evidence we have of a pup in the wild, making this a definitive birthing location.”

Many scholars believe great whites are born farther out at sea. That this pup was filmed so close to shore — roughly 1,000 feet from the beach — is significant because its age means it was likely born in shallow waters.

Great whites are listed as an international endangered species. “Further research is needed to confirm these waters are indeed a great white breeding ground. But if it does, we would want lawmakers to step in and protect these waters to help white sharks keep thriving,” Sternes said.