Scientists at Northwestern University found that people became less sensitive to food odors based on the meal they had eaten just before. These findings show that just as smell regulates what we eat, what we eat -- in turn -- regulates our sense of smell. Phys.Org reports: The study found that participants who had just eaten a meal of either cinnamon buns or pizza were less likely to perceive "meal-matched" odors, but not non-matched odors. The findings were then corroborated with brain scans that showed brain activity in parts of the brain that process odors was altered in a similar way. Feedback between food intake and the olfactory system may have an evolutionary benefit, said senior and corresponding study author Thorsten Kahnt, an assistant professor of neurology and psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine. "If you think about our ancestors roaming the forest trying to find food, they find and eat berries and then aren't as sensitive to the smell of berries anymore," Kahnt said. "But maybe they're still sensitive to the smell of mushrooms, so it could theoretically help facilitate diversity in food and nutrient intake." Kahnt said while we don't see the hunter-gatherer adaptation come out in day-to-day decision-making, the connection between our nose, what we seek out and what we can detect with our nose may still be very important. If the nose isn't working right, for example, the feedback loop may be disrupted, leading to problems with disordered eating and obesity. There may even be links to disrupted sleep, another tie to the olfactory system the Kahnt lab is researching. Kahnt said with a better understanding of the feedback loop between smell and food intake, he's hoping to take the project full circle back to sleep deprivation to see if lack of sleep may impair the loop in some way. He added that with brain imaging, there are more questions about how the adaptation may impact sensory and decision-making circuits in the brain. The study has been published in the journal PLOS Biology.

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An anonymous reader quotes a report from ScienceAlert: An artery that temporarily runs down the center of our forearms while we're still in the womb isn't vanishing as often as it used to, according to researchers from Flinders University and the University of Adelaide in Australia. That means there are more adults than ever with what amounts to be an extra channel of vascular tissue flowing under their wrist. "Since the 18th century, anatomists have been studying the prevalence of this artery in adults and our study shows it's clearly increasing," Flinders University anatomist Teghan Lucas said in 2020. "The prevalence was around 10 percent in people born in the mid-1880s compared to 30 percent in those born in the late 20th century, so that's a significant increase in a fairly short period of time, when it comes to evolution." To compare the prevalence of this persistent blood channel, Lucas and colleagues Maciej Henneberg and Jaliya Kumaratilake from the University of Adelaide examined 80 limbs from cadavers, all donated by Australians of European descent. The donors raged from 51 to 101 on passing, which means they were nearly all born in the first half of the 20th century. Noting down how often they found a chunky median artery capable of carrying a good supply of blood, the research team compared the figures with records dug out of a literature search, taking into account tallies that could over-represent the vessel's appearance. Their results were published in 2020 in the Journal of Anatomy. The fact the artery seems to be three times as common in adults today as it was more than a century ago is a startling find that suggests natural selection is favoring those who hold onto this extra bit of bloody supply.

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