Health
Humans’ Wounds Heal Much More Slowly Than Other Mammals’
Watching wild baboons in Kenya, Akiko Matsumoto-Oda, an evolutionary biologist and primatologist at the University of the Ryukyus in Japan, had a front-row seat to the violence between these monkeys, especially the males.
“I was struck by how frequently they sustained injuries,” she said, “and, even more, by how rapidly they recovered — even from seemingly severe wounds.”
Compared with her own experiences with nicks and cuts, the baboons’ ability to heal seemed like a superpower.
In a study published on Wednesday in Proceedings of the Royal Society B, Dr. Matsumoto-Oda and her colleagues compared the healing rates of humans, chimpanzees, monkeys and mice. They found that human wounds took more than twice as long to heal as wounds of any of the other mammals. Our slow healing may be a result of an evolutionary trade-off we made long ago, when we shed fur in favor of naked, sweaty skin that keeps us cool.
When possible, the researchers wanted to study healing in a way that was less violent and more controlled than watching wild baboons.
To measure human healing, they recruited 24 patients who were having skin tumors removed at the University of the Ryukyus Hospital. To gather data on chimpanzees, which are some of our closest animal relatives, researchers observed five captive chimps at the Kumamoto Sanctuary of the Kyoto University Wildlife Research Center, which houses animals formerly used in pharmaceutical research. The chimps’ wounds, like those of wild baboons, mostly came from tiffs between the animals.
The study’s other primate subjects, all kept at the Kenya Institute of Primate Research, included olive baboons, Sykes’ monkeys and vervet monkeys. Researchers anesthetized the monkeys, surgically wounded them and then monitored their recovery. “As a field researcher, I personally believe that invasive studies should be minimized as much as possible,” said Dr. Matsumoto-Oda, who noted that bite wounds on wild baboons are often similar in size to the surgical wounds in the study, but deeper.
Finally, to compare humans and primates with more distantly related mammals, researchers anesthetized and surgically wounded mice and rats.
Based on her field observations, Dr. Matsumoto-Oda was prepared to see humans healing more slowly than the other animals. The 24 people regrew skin at about a quarter of a millimeter per day, on average.
What surprised Dr. Matsumoto-Oda more was the consistency between the healing rates of the animal subjects, including chimpanzees. There was no significant difference in the speedy skin regrowth among different primates, which grew about 0.62 millimeters of new skin per day, or between primates and rodents. Humans were the clear outliers.
Elaine Fuchs, a stem cell biologist at the Rockefeller University who studies skin growth and repair and was not involved in the new research, said the results were what she would have expected. That’s because skin healing depends on hair.
Each hair grows from a hair follicle, which also houses stem cells. Normally, those stem cells just make more hair. But when called upon, they can grow new skin instead. “When the epidermis is wounded, as in most kinds of scratches and scrapes, it’s really the hair-follicle stem cells that do the repair,” Dr. Fuchs said.
Furry animals are covered in follicles, which help quickly close up wounds in mice or monkeys. By comparison, “human skin has very puny hair follicles,” Dr. Fuchs said. And our ancestors lost many of those follicles, packing their skin with sweat glands instead. Sweat glands also have stem cells, but they’re much less efficient at repairing wounds, Dr. Fuchs said.
Why did we make that trade during evolution, giving up so much of our hair and its protective properties? The glands that make the watery, salty sweat that dampens our shirts on a hot day are called eccrine glands. Most furry mammals have them only in certain places, mainly the soles of their paws. But human ancestors went all-in on sweat — modern humans have millions of sweat glands all over our bodies, and they’re about 10 times denser than those of chimpanzees.
“We evolved to cool by sweating profusely,” said Daniel Lieberman, an evolutionary biologist at Harvard University. Our abundant sweat glands and lack of fur let our ancestors engage in physical activity in hot environments, Dr. Lieberman said, and cooled the machinery of our big brains.
The benefits of trading hair for sweat must have outweighed the costs. Dr. Matsumoto-Oda and her co-authors speculate that social support among prehistoric humans might have helped wounded people stay alive, despite our slower healing. (Or maybe they had ways to treat wounds, like orangutans and chimps seem to.)
“The evolutionary disadvantage is that wound healing is slowed,” Dr. Fuchs said, but humans also gained evolutionary advantages by losing hair.
“They can put on a coat if they need to,” she added.
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No sex for the win? This was the advice given to this year’s NBA champions.
New York Knicks owner James Dolan addressed the now-champs as they headed into the playoffs in April 2026, acknowledging their high potential to eventually win the championship.
“I don’t know if you understand what it would mean for you to win a championship this year … It would be life-changing,” he said. “It will stick with you the rest of your lives, and if you don’t win, you’ll be thinking about it the rest of your lives.”
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As Dolan’s inspirational speech to the team went on, he explained how the next 10 weeks would require each player to make sacrifices – watching their diets, getting proper sleep and perhaps even abstaining from sex.
“You need sacrifice and you need to eliminate all the distractions around you,” he said.
Jalen Brunson of the New York Knicks celebrates with the Bill Russell NBA Finals Most Valuable Player Award trophy and Knicks owner James Dolan after defeating the San Antonio Spurs in Game Five of the 2026 NBA Finals at Frost Bank Center in San Antonio, Texas, on June 13, 2026. (Gregory Shamus/Getty Images)
“I had this idea that maybe you should give up sex for the next 10 weeks,” the owner said. “You don’t have to give up sex for the next 10 weeks – but, like the Spartans … They denied themselves, so that they can have an edge. Get the edge.”
This received a few snickers from the team, and Dolan responded, “Don’t tell [your wives and girlfriends] you’re not going to have sex and don’t tell them it was my idea. But let them know what this is going to be like … and how they’re going to have to sacrifice, too.”
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Dr. Anna Elton, licensed marriage and family therapist and clinical sexologist in Massachusetts, confirmed that this belief has been around for centuries, dating back to the ancients Spartans and early Olympic competitors.
Avoiding sex can preserve energy, increase aggression and sharpen focus, according to Elton.
The theory behind abstaining from sex for better athletic performance supports that it can preserve energy, increase aggression and sharpen focus. (iStock)
But modern research has found little evidence that consensual sexual activity negatively impacts strength, endurance, reaction time or athletic performance when it occurs at least 10 hours before competition, the doctor countered.
However, “activity very close to competition may affect recovery measures,” she added. What may be more important, according to Elton, is the psychological value of abstinence.
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“Choosing to abstain can reinforce discipline and total commitment to a larger goal,” she said. “In those cases, the advantage may come more from mindset and focus than from any physical effect.”
“Whether the sacrifice is alcohol, social activities, favorite foods or sex, the message is often the same: ‘We are all in.’”
New York Knicks guard Jalen Brunson celebrates with teammates after the Knicks defeated the San Antonio Spurs in game five of the 2026 NBA Finals at Frost Bank Center in San Antonio, Texas, on June 13, 2026. (Geoff Burke/Imagn Images)
The science of abstinence
This discussion has historically focused on men, which Elton said is often based on “misconceptions about testosterone and energy depletion.”
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“Research has not demonstrated that normal sexual activity causes a meaningful decline in athletic performance, and concerns about testosterone depletion have not been consistently supported by the evidence,” she said.
“For women, sexual activity may have additional benefits related to stress reduction, emotional regulation and relationship satisfaction.”
Abstaining from sex for athletic performance may create a sense of discipline, minimize distractions, maintain focus on training and reinforce a team culture centered on sacrifice and commitment, experts say. (iStock)
In a separate interview with Fox News Digital, Dr. Anthony Puopolo, a men’s health expert and lead medical provider for RexMD, echoed Elton’s assessment that research largely does not support abstinence as a performance enhancer.
This is despite a small amount of evidence that suggests engaging in sexual activity within two hours of competition could pose a risk to cardiovascular recovery.
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“Unfortunately, nearly all studies (99%) have been conducted in males aged 20 to 40, so there is virtually no data on female athletes, older athletes or diverse populations,” said the Puerto Rico-based expert. “We know what to tell the Knicks, but we are not sure what to recommend for the New York Liberty.”
Importance of connection
Elton said abstinence may still offer psychological benefits for some competitors. “For some athletes, it can become part of a pre-competition ritual that enhances confidence,” she told Fox News Digital.
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Some other potential benefits of sexual activity include stress reduction, improved sleep, mood enhancement, emotional connection with a partner and relief from performance-related tension.
“Strong, supportive relationships are associated with better psychological resilience, which can be valuable during high-pressure competitions,” Elton said.
“One of the most overlooked performance advantages may be having a supportive relationship waiting at home,” a doctor said. (iStock)
“Ultimately, there is no universal rule,” she went on. “What helps one athlete perform at their best may not help another.”
Elton stressed that sleep, recovery, nutrition, stress management and support from loved ones are universal performance boosters.
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“Athletes devote tremendous attention to training their bodies, while overlooking the importance of their personal relationships,” she cautioned. “A supportive partner can be one of the greatest assets during a demanding season.”
“If competition requires temporary sacrifices, make those decisions together and keep communication open.”
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Eliminating sugar from your diet may seem like the key to healthy eating, but research suggests it could have unintended effects on digestive health.
A study presented at ENDO 2026, the Endocrine Society’s annual meeting, suggests that a total lack of sucrose, or table sugar, may harm gut health and disrupt the body’s natural metabolism.
To explore how the total absence of dietary sugar impacts the body, researchers at the Dasman Diabetes Institute in Kuwait City conducted a 16-week study on two groups of mice. Both groups were placed on a low-fat diet, but with one critical difference.
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One group consumed a low-fat diet that included a standard amount of sucrose, while the other group ate a low-fat diet that was completely sugar-free, according to the study’s press release.
Throughout the trial, the scientists monitored a wide variety of physiological factors, including the animals’ weight, glucose tolerance, insulin sensitivity, hormone levels, internal inflammation and the specific composition of their gut bacteria.
A total lack of dietary sugar can cause imbalances in the gut bacteria and lead to signs of fatty liver disease, even without any weight gain, researchers said. (iStock)
The study outcome suggested that completely removing sugar caused several unexpected health problems.
“Completely removing sucrose from a low-fat diet may unexpectedly disrupt gut health and promote inflammation and metabolic dysfunction,” Rasheed Ahmad, principal scientist and head of the Immunology & Microbiology Department at the Dasman Diabetes Institute, said in the release.
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Even though the mice on the sugar-free diet did not gain any extra weight compared to the control group, their internal health indicators deteriorated.
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The animals that lacked sucrose developed an imbalance in their gut microbes and increased inflammation within the intestines and liver.
They also showed signs of poor glucose regulation, insulin resistance and cellular changes associated with fatty liver disease, according to the research.
Future dietary guidelines may shift away from strict, absolute sugar bans and instead focus on overall gut health through balanced nutrition. (iStock)
“The findings suggest that complete removal of sucrose from a low-fat diet may negatively affect gut microbiota and metabolic health,” Ahmad concluded.
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While the risks of high-sugar diets are well-established, the researchers noted that little attention has been given to the effects of completely eliminating sugar from low-fat meals.
Scientists say these new findings highlight that dietary carbohydrates play a valuable role in supporting balance between the immune system and the gut microbiome.
Completely cutting sucrose from a low-fat diet can unexpectedly trigger gut inflammation and disrupt the metabolism, experts say. (iStock)
Because this research was conducted on mice over a relatively short 16-week period, further clinical trials are necessary to determine whether a completely sugar-free diet causes the same gut and liver inflammation in humans.
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Additionally, the study focused specifically on removing sucrose from low-fat meals, meaning the results might not apply to people eliminating sugar while following higher-fat or ketogenic eating plans, the researchers noted.
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The team believes that future dietary guidelines may shift away from strict, absolute sugar restrictions and instead place a greater emphasis on maintaining a diverse, healthy population of gut bacteria through balanced nutrition.
“In the long term, these findings could help improve strategies for preventing and managing metabolic disorders, fatty liver disease and chronic inflammatory conditions,” Ahmad said.
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