- Researchers are finding a new feature of human evolution.
- Humans have evolved to use less water a day than other primates.
- The nose is one of the factors that allows people to be water efficient.
Scientists have discovered a new feature that makes humans different from other primates, such as chimpanzees. Research shows that the human body uses 30% to 50% less water per day than our closest animal relatives.
Sure, the power of our brains and the ability to walk upright are essential to make us special, but the efficiency with which the human body consumes water is another major difference. This feature probably appeared as an evolutionary adaptation to ancient hunter-gatherers, who had to venture more and more from water sources in search of food, believes the study’s lead author, Herman Pontzer, an associate professor of evolutionary anthropology at Duke University.
“Even the mere possibility of going a little further without water would have been a great advantage, as the first people began to earn a living in dry landscapes and savannas,” Pontzer said.
Because our body constantly gets rid of water through processes such as urination or sweating, it is necessary for water levels to be restored. “In order to sustain life, humans and other terrestrial animals must maintain a close balance of gain and loss of water every day,” as the authors of the paper write.
For the study, researchers analyzed this cycle of water consumption and loss in 309 people from a variety of backgrounds. Among them were farmers, hunter-gatherers and office workers, who were compared to 72 monkeys scattered in zoos and sanctuaries.
A rotating model of water for humans and chimpanzees that have similar free fat masses and water pools in the body.
Credit: Current biology
The scientists calculated the water intake of each person in the study, whether it came from drinks or food. They also tracked the amount of water lost through urine, sweat or the gastrointestinal tract. With all the numbers added, it became clear that the body of an ordinary person goes through about 3 liters of water every day. That’s about 12 cups. A chimpanzee or a gorilla passes twice as long.
The results were surprising, as humans tend to sweat more than other primates. In a square centimeter of skin, “humans have 10 times more sweat glands than chimpanzees,” Pontzer explained. We can sweat about half a gallon in a 30-minute workout. We also lead much more active lives than the zoo monkeys, most monkeys move only a few hours a day, according to scientists. So how do you consume much less water?
The researchers believe that the real difference in water processing they observed in humans compared to other primates is related to evolutionary mechanisms. Our bodies have had to adapt to needing less water to stay healthy.
Scientists are now focusing on finding out exactly how this change took place. The data suggest that our sense of thirst was different from other monkey relatives. We just don’t want that much water. In particular, the ratio of water to calories is 25% lower in human breast milk than in monkey milk.
It is also possible that our nose has a lot to do with this. Fossils indicate that humans began to receive more prominent noses than their evolutionary cousins about 1.6 million years ago, at the dawn of Homo erectus. Instead, gorillas and chimpanzees have a flatter nose.
What’s good about our noses? Because we tend to breathe water vapor, the nasal passages cool and condense it, turning it back into fluid. This fluid collects in the nose and reappears back into the body. In essence, having a protruding nose probably helped the ancient people keep more moisture when they breathe.
Read the study published in Current Biology.