- Researchers find 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 humans to be water efficient.
Scientists have discovered a new feature that distinguishes humans from other primates such as chimpanzees. Research shows that the human body uses 30% to 50% less water a day than our closest animal relatives.
Certainly, our brain power and our ability to walk upright are key to making us special, but the efficiency with which the human body consumes water is another important difference. This feature probably occurred as an evolutionary adaptation in ancient hunter-gatherers, who had to venture further and further away from water sources in search of food, according to the study’s lead author. , Herman Pontzer, Associate Professor of Evolutionary Anthropology at Duke University.
“Even being able to go a little further without water would have been a great advantage when the first humans began to make a living in dry, savannah landscapes,” Pontzer said.
Because our body is constantly removed from the water through processes such as urinating or sweating, water levels need to be restored. “To sustain life, humans and other terrestrial animals must maintain a narrow balance of water gains and losses every day,” the authors of the paper write.
For the study, researchers examined this cycle of water consumption and loss in 309 people from diverse backgrounds. Among them were farmers, hunter-gatherers and office workers, who were compared to 72 apes scattered throughout the zoos and sanctuaries.
A water replacement model for humans and chimpanzees that have a body water mass similar to fat-free mass and fat.
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 gastrointestinal tract. With all the figures added up, it became clear that the body of an average person spends about 3 liters of water every day. They are about 12 cups. A chimpanzee or gorilla goes through the double.
The results were surprising because humans tend to sweat more than other primates. In a square inch 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 apes at the zoo, most apes only move a couple of hours a day, according to scientists. So how do we spend so 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 had to adapt to needing less water to stay healthy.
Scientists are now focusing on finding out exactly how this change came about. The data suggest that our sense of thirst diverged from other ape relatives. We just don’t want that much water. It should be noted that the proportion of water to calories is 25% less in human breast milk than in ape milk.
It is also possible that our nose has a lot to do with this. Fossils point to humans starting to get more protruding noses than their evolutionary cousins about 1.6 million years ago, with the dawn of Homo erectus. In contrast, gorillas and chimpanzees have a flatter nose.
What good is our noses? As we tend to breathe water vapor, the nasal passages actually cool and condense, turning it back into liquid. This fluid gathers inside the nose and is re-appropriated to the body. Essentially, having a protruding nose would probably help ancient humans maintain more moisture when breathing.
Read the study published in Current Biology.