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Boston Globe
31-05-2025
- Science
- Boston Globe
Your cat may or may not love you, but it knows your scent
Get Love Letters: The Newsletter A weekly dispatch with all the best relationship content and commentary – plus exclusive content for fans of Love Letters, Dinner With Cupid, weddings, therapy talk, and more. Enter Email Sign Up Through referrals from friends and colleagues, the researchers recruited 30 cats and their owners to participate in the study. The cats' owners captured their own scents by rubbing cotton swabs behind their ears, between their toes and under their armpits. Eight additional people who don't own pets and didn't know the cats' owners were recruited to be 'odor donors.' Advertisement Each of the study cats, in the comfort of its own home, was then presented with an array of test tubes containing the smelly cotton swabs from its owner, a stranger and a blank control. A camera mounted to the experimental setup recorded the cats' reactions to the test tubes. Advertisement The cats spent more time sniffing the samples from the strangers than from their owners -- an indication that the cats could recognize their owners' scents and devoted more time to exploring the ones they'd never smelled before. While this finding might seem like common sense, it's 'a very important piece of information,' said Dr. Carlo Siracusa, an associate professor of animal behavior at the University of Pennsylvania School of Veterinary Medicine who was not involved with the study. 'This is how science works. You need to prove everything.' A Black Silver Turkish Angora relaxed between judging sessions at the Catsachusetts show in April. Uchiyama and his colleagues further analyzed video recordings of the cats sniffing the test tubes and observed the cats predominantly using their right nostrils to smell the strangers' test tubes, regardless of where the tube was placed within the array. These findings seemed to corroborate previous studies of other animals, including dogs, which also led with their right nostrils when exploring strange scents. 'The left nostril is used for familiar odors, and the right nostril is used for new and alarming odors, suggesting that scenting may be related to how the brain functions,' Uchiyama said. 'It is likely that the right brain is preferred for processing emotionally alarming odors.' Related : Siracusa urged caution in interpreting whether the cats' sniffing behavior relates to brain function. 'The study did not prove that the right side of the brain is activated,' he said. Proving that will require cats willing to cooperate with having their brains scanned while they sniff things. While further research is needed to confirm whether the nostril cats use to smell people is a window into the feline mind, Siracusa said that studies like Uchiyama's are important for furthering human understanding of feline behavior, which can help us provide better care for them. He also remarked on the logistical feat of designing a study protocol deemed acceptable by its feline participants. Advertisement 'I really commend this group of scientists for being successful in engaging 30 cats in doing this stuff,' Siracusa said. 'Most cats want nothing to do with your research.' This article originally appeared in .
Observer
04-03-2025
- Health
- Observer
Why do women live longer than men?
Women outlive men by something of a long shot: In the United States, women have a life expectancy of about 80, compared with around 75 for men. This holds regardless of where women live, how much money they make, and many other factors. It's even true for most other mammals. 'It's a very robust phenomenon all over the world, totally conserved in sickness, during famines, during epidemics, even during times of starvation,' said Dr. Dena Dubal, a professor of neurology at the University of California, San Francisco. But the reasons women live longer are complicated and less established — and the fact that they are outliving men doesn't necessarily mean they are living better. Women tend to have shorter health spans (the number of healthy years a person lives) than men, said Bérénice Benayoun, an associate professor at the USC Leonard Davis School of Gerontology. Women are generally more physically frail than men in old age; they're also more vulnerable, particularly after menopause, to developing cardiovascular issues and Alzheimer's disease, in part because age itself is a risk factor for those conditions, Benayoun said. Scientists are trying to uncover the reasons men and women age differently in the hopes of extending the life span and health span for both. 'If we can understand what makes one sex more resilient or vulnerable, then we have new pathways, new molecular understanding, for new therapeutics that could help one or both sexes also be resilient,' Dubal said. Here's what they know so far about what causes the longevity gap. Genetics A growing body of research suggests that the XX set of female sex chromosomes (which, along with other chromosomes, carry our DNA) may impact longevity, though it's not clear exactly how. For example, a 2018 study conducted by Dubal's lab looked at genetically manipulated mice with different combinations of sex chromosomes and reproductive organs. Those with two X chromosomes and ovaries lived longest, followed by mice with two X chromosomes and testes. Mice with XY chromosomes had shorter life spans. 'There was something about the second X chromosome that was protecting the mice from dying earlier in life, even if they had testes,' Dubal said. 'What if there was something on that second X chromosome that was in some ways a sprinkle of the fountain of youth?' Scientists haven't yet examined this in humans, but Dubal said the fact that we have the same hormones and sex chromosomes and similar reproductive systems suggests that the findings could be similar in people. Epigenetic factors — environmental or lifestyle elements like climate or chronic stress that impact which genes are expressed, and how — may also play a role in life span, widening or shrinking the disparities between men and women, said Montserrat Anguera, an associate professor of biomedical sciences at the University of Pennsylvania School of Veterinary Medicine, who studies this topic. Hormones Researchers are also investigating the role of sex hormones like estrogen in longevity and are especially interested in the effect they have on the immune system. 'Decent data is showing that, at least before menopause, the female immune system tends to be better, more on it and better able to mount responses,' Benayoun said. In general, males 'tend to do much worse in response to infection,' which in turn could shorten their life spans; they're also more likely than women to die of sepsis, she said. One 2017 analysis found that women who experienced menopause later in life — older than 50 — lived longer than those who experienced it earlier. When estrogen levels drop, such as during menopause, women's immune systems seem to weaken. Women tend to catch up to (or surpass) men in terms of developing diseases that were less common before menopause, Benayoun said. Lifestyle and Behavior Behavioral patterns play a key role in the disparity. Women are generally less likely than men to smoke or drink heavily — behaviors that contribute significantly to mortality, said Kyle Bourassa, a psychologist and a senior fellow at the Center for the Study of Aging and Human Development at Duke University. Women also tend to practice more 'health-promoting behavior,' like wearing a seat belt or going to the doctor for annual checkups, Bourassa said. In addition, he said that women are more likely than men to socialize, protecting them from the detrimental effects of social isolation and loneliness. A 2023 analysis found they're also less likely to die by drug overdose or suicide. External Factors On a broader societal level, issues like war or gun violence disproportionately impact men, said Naoko Muramatsu, a professor of community health sciences at the University of Illinois Chicago. During the COVID pandemic, men died at higher rates than women. Research showed that they were more likely to hold jobs that exposed them to the virus, like food preparation or construction, or to be homeless or incarcerated, all of which affected mortality rates. Ultimately, it's a combination of all these factors that determines the life span gap, said Alan Cohen, an associate professor of environmental health sciences at Columbia University Mailman School of Public Health. 'There's probably a thousand ways that that's happening.' And even though we do have control over some factors, like drinking, smoking and diet, it's not yet clear how significantly longevity would be impacted by changing those behaviors, Bourassa said. 'We need randomized control trials to tease these things apart,' he said. This article originally appeared in
New York Times
25-02-2025
- Health
- New York Times
Why Do Women Live Longer Than Men?
Women outlive men, by something of a long shot: In the United States, women have a life expectancy of about 80, compared to around 75 for men. This holds true regardless of where women live, how much money they make and many other factors. It's even true for most other mammals. 'It's a very robust phenomenon all over the world, totally conserved in sickness, during famines, during epidemics, even during times of starvation,' said Dr. Dena Dubal, a professor of neurology at the University of California, San Francisco. But the reasons women live longer are complicated and less established — and the fact that they are outliving men doesn't necessarily mean they are living better. Women tend to have shorter health spans (the number of healthy years a person lives) than men, said Bérénice Benayoun, an associate professor at the U.S.C. Leonard Davis School of Gerontology. Women are generally more physically frail than men in old age; they're also more vulnerable, particularly after menopause, to developing cardiovascular issues and Alzheimer's disease, in part because age itself is a risk factor for those conditions, Dr. Benayoun said. Scientists are trying to uncover the reasons men and women age differently in the hopes of extending life span and health span for both. 'If we can understand what makes one sex more resilient or vulnerable, then we have new pathways, new molecular understanding, for new therapeutics that could help one or both sexes also be resilient,' Dr. Dubal said. Here's what they know so far about what causes the longevity gap. Genetics A growing body of research suggests that the XX set of female sex chromosomes (which, along with other chromosomes, carry our DNA) may impact longevity, though it's not clear exactly how. For example, a 2018 study conducted by Dr. Dubal's lab looked at genetically manipulated mice with different combinations of sex chromosomes and reproductive organs. Those with two X chromosomes and ovaries lived longest, followed by mice with two X chromosomes and testes. Mice with XY chromosomes had shorter life spans. 'There was something about the second X chromosome that was protecting the mice from dying earlier in life, even if they had testes,' Dr. Dubal said. 'What if there was something on that second X chromosome that was in some ways a sprinkle of the fountain of youth?' Scientists haven't yet examined this in humans, but Dr. Dubal said the fact that we have the same hormones and sex chromosomes, and similar reproductive systems, suggests that the findings could be similar in people. Epigenetic factors — environmental or lifestyle elements like climate or chronic stress that impact which genes are expressed, and how — may also play a role in life span, widening or shrinking the disparities between men and women, said Montserrat Anguera, an associate professor of biomedical sciences at the University of Pennsylvania School of Veterinary Medicine, who studies this topic. Hormones Researchers are also investigating the role of sex hormones like estrogen in longevity, and are especially interested in the effect they have on the immune system. 'There's decent data showing that, at least before menopause, the female immune system tends to be better, more on it and better able to mount responses,' Dr. Benayoun said. In general, males 'tend to do much worse in response to infection,' which in turn could shorten their life spans; they're also more likely than women to die of sepsis, she said. One 2017 analysis found that women who experienced menopause later in life — over age 50 — lived longer than those who experienced it earlier. When estrogen levels drop, such as during menopause, women's immune systems seem to weaken. And women tend to catch up to (or surpass) men in terms of developing diseases that were less common before menopause, Dr. Benayoun said. Lifestyle and Behavior Behavioral patterns play a key role in the disparity. Women are generally less likely than men to smoke or drink heavily — behaviors that contribute significantly to mortality, said Kyle Bourassa, a psychologist and a senior fellow at the Center for the Study of Aging and Human Development at Duke University. Women also tend to practice more 'health-promoting behavior,' like wearing a seatbelt or going to the doctor for annual checkups, Dr. Bourassa said. In addition, he said that women are more likely than men to socialize, protecting them from the detrimental effects of social isolation and loneliness. A 2023 analysis found they're also less likely to die by drug overdose or suicide. External Factors On a broader societal level, issues like war or gun violence disproportionately impact men, said Naoko Muramatsu, a professor of community health sciences at the University of Illinois Chicago. During the Covid pandemic, men died at higher rates than women. Research showed that they were more likely to hold jobs that exposed them to the virus, like food preparation or construction, or to be homeless or incarcerated, all of which affected mortality rates. Ultimately, it's a combination of all these factors that determines the life span gap, said Alan Cohen, an associate professor of environmental health sciences at Columbia University Mailman School of Public Health. 'There's probably a thousand ways that that's happening.' And even though we do have control over some factors, like drinking, smoking and diet, it's not yet clear how significantly longevity would be impacted by changing those behaviors, Dr. Bourassa said. 'We need randomized control trials to tease these things apart,' he said.
