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Technology

Study: Genetic tweaks allowed early humans to walk on two legs

Two small changes in human DNA may have played a big role in helping our ancestors walk upright, researchers say. The study, recently published in the journal Nature, found that these tweaks changed how a key hip bone developed. This allowed early humans to stand, balance and walk on two legs instead of moving on all fours like other primates. One change caused the ilium -- the curved bone you feel when you put your hands on your hips -- to rotate 90 degrees. This shifted how muscles attached to the pelvis, transforming a structure once used for climbing into one built for upright walking. The other genetic change slowed down how the ilium hardened into bone, giving it more time to expand sideways and form a short, bowl-shaped pelvis. These changes were "essential for creating and shifting muscles that are usually on the back of the animal, pushing the animal forward, to now being on the sides, helping us stay upright as we walk," study co-author Terence Capellini, an evolutionary biologist at Harvard University, said. The researchers examined samples of developing pelvic tissue from humans, chimpanzees and mice, pairing microscopic samples with CT imaging. They found that in humans, pelvic cartilage grows sideways rather than vertically as it does in other primates, and that it hardens later, allowing the structure to widen as it forms. Further analysis revealed that the difference came from subtle changes in gene regulation -- the "on-off switches" that control how and when certain genes are active. In humans, cartilage-forming genes switched on in new regions, prompting horizontal growth, while bone-forming genes activated later, slowing the hardening process. Because primates share most of the same developmental genes, researchers believe these changes appeared early in human evolution, after our lineage split from chimpanzees. "What Terry and his lab's work has shown is that it's not just a rotation, it's a different way of growing," University of Missouri anthropologist Carol Ward, who was not involved in the study, told Science News. "One of the most significant things about this change is it shows how critical it was to establish the ability to stand on one foot at a time, which lets us walk on two feet," Ward said. Interestingly, this research didn't start as an evolutionary study. Funded by the National Institutes of Health, researchers originally set out to understand how the pelvis forms to improve treatments for hip disorders. "It was geared towards biomedical research," Capellini told Science News, "understanding how you build a pelvis and why it's different [from other primates and mice], and more importantly, why it leads to disease." What's more, the same evolutionary adaptations that enabled walking may also have made the human hip more prone to osteoarthritis, the researchers noted. And, Capellini added, those wider hips may have also created a roomier birth canal, making it easier for humans to give birth to larger-brained babies as evolution progressed. More information The Smithsonian's Human Origins Program has more on human evolution. Copyright © 2025 HealthDay. All rights reserved.

Technology

Gut muscle rhythm may explain how blood vessels in brain work together

The human body is packed with natural rhythms, from your sleep-wake cycle to the steady pulsing of blood through the brain to heart rate and pulse. Now, scientists say the gut may hold the key to understanding how this complex coordination happens in the brain's blood vessels. Researchers at the University of California San Diego have discovered that the gut's rhythmic muscle movements could help explain how blood vessels in the brain expand and contract together. Their findings were published recently in the journal Physical Review Letters. When neurons in the brain are stimulated, tiny blood vessels called arterioles expand to deliver more oxygen and nutrients. These vessels pulse and are often in sync with one another. But for years, scientists have puzzled over how this synchronization occurs. The UC San Diego team turned to the digestive system for answers. They found that the intestines, which naturally contract in waves to move food through, rely on a pattern of synchronized oscillations that form a staircase effect. This same pattern, the researchers say, could also explain how brain blood vessels work together in harmony. "Coupled oscillators talk to each other and each section of the intestine is an oscillator that talks to the other sections near it," Massimo Vergassola, professor of physics at UC San Diego, said in a news release. "Normally, coupled oscillators are studied in a homogeneous setting, meaning all the oscillators are at more or less similar frequencies," he continued. "In our case, the oscillators were more varied, just as in the intestine and the brain." Using mathematics, the researchers showed how nearby oscillators -- whether in the gut or the brain - can lock onto each other's rhythm if their frequencies are similar. This creates step-like transitions, similar to the way food moves smoothly through the intestines. "The mathematics had been solved in an approximate way before now, but not in a way that gave you these breaks and what happens at the breaks. That's a critical discovery," David Kleinfeld, professor of physics and neurobiology at UC San Diego, said. The new findings could eventually help scientists better understand not only brain function but also digestive issues affecting the movement of food, liquids and waste through the gastrointestinal tract. "The brain is infinitely more complicated than the gut, but this is science at its best," Kleinfeld said. "You ask one question, it leads you somewhere else, you solve that problem, then return to your original question." More information Johns Hopkins Medicine has more on the brain-gut connection. Copyright © 2025 HealthDay. All rights reserved.