Food processing before eating, key in human evolution – Puranoticia

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A study from Harvard University in the United States, reveals that our ancestors made between 2 and 3 million years began to spend much less time and chewing the food effort by adding meat to their diet and using tools to process food. Researchers estimate that the food would have saved early humans at least 2.5 million quids per year and made possible new changes to help make us human.

One of the greatest mysteries of human evolution it is how species such as Homo erectus, smaller teeth, smaller faces and smaller stomachs, could get more energy from food to their larger brains and bodies before they invented cooking.

“what we showed is that by processing food, especially meat, before eating, humans not only reduce the effort required to chew, but also chew much more effectively,” said Katie Zink, first author study and laboratory member Daniel Lieberman, professor of Biological Sciences at Harvard.

When you change your diet to include 33 percent of meat and food processing –rebanar meat and vegetables-hitting – before eating, Zink and Lieberman found that the muscular effort required to chew and the number of quids needed per day was reduced by almost 20 percent. They also saw that simply cutting the meat with simple tools available more than 2 million years ago, humans were able to swallow small pieces more easily digestible than it would have been possible without tools.

“Eating meat and use stone tools to process food apparently made possible a key reduction of the jaws, teeth and chewing muscles that occurred during human evolution, “says Zink. But analyze such a basic process as chewing is not as easy as atractivo– –or as it may seem

“What did Katie was creative but sometimes, frankly, a little stomach churned. – -revela Lieberman–. not only did people come into the lab, chewing raw meat and other foods and spit them out, but then had to analyze substances “.

to approximate the tenacity and texture of dams that early humans ate, Zink and Lieberman, after much experimentation, focused on the use of goat, subjects chewed raw as Zink used instruments connected to your jaw to measure the effort involved.

in each test, the volunteers were given in random order, a selection of raw -cabra prepared in various ways, sliced, crushed and cooked food as well as various vegetables, including carrots, beets and sweet potatoes. After chewing each bite until they could swallow normally, subjects spit food. Zink then extended the individual particles of food on a tray, the photographed and digitally measured their sizes.

“What we found was that humans can not eat raw meat effectively with their teeth low crown. When people give to raw goat chew and chew and chew, and most of the meat is still a large group. it’s like gum –describe Lieberman–. But once started processing mechanically, if only cutting it, the effects on performance were dramatic chew “.

” chewing is one of the key features of a mammal –añade Lieberman–. most other animals such as reptiles, just they chew their food;. only swallow the whole food developing the ability to chew food into smaller particles gave mammals a big boost of extra energy because smaller particles have a higher surface to volume ratio, allowing digestive enzymes to process them more efficiently. “

* Chewing least trigger for hunting and gathering *

However, most mammals have diet relatively low quality , with cows, for example, eating grass and hay although they have to spend most of the day munching. Even the closest relatives apes to humans, with a diet consisting mainly of fruits, spend almost half their day chewing to extract enough energy from their food, emphasizes Lieberman, whose work is published Wednesday in Nature.

“But we humans have done something truly remarkable -celebra–. we eat even higher quality foods that chimpancésy spend less time chewing.” However, this change presented a new challenge to the first humans. One of the critical components of a better quality diet is meat, which is very difficult for humans to chew effectively

“Meat has a lot of nutrients, but also very elastic. you can think of it like a rubber band Zink– explains. So the problem is we can not break it down with our flat teeth with low crown. but if cut, then it is not necessary to use the teeth to break it down so much and can be swallowed in much smaller particles. the cooking makes it even easier to chew. “

This pre-processing and reductions effort gum that come with it, according pose Zink and Lieberman, may have opened the door to one of the lifestyle changes leading life in human evolution: the emergence of hunting and gathering

“with the origin of the genus Homo ‘snouts and we have big teeth and big chewing muscles pair smaller and lower teeth chewing muscles, and reduction –detalla Lieberman– nose. These changes, and others, have enabled speech and other changes in the head, as larger brains. To some extent, it is the simplest of all technology: cut the meat into smaller pieces and hit the vegetables before chewing “

Although many aspects of our biology changed when the genus Homo ‘evolved. Zink and Lieberman say the food processing before eating almost certainly played a role. “One of the innovations that helped us make us human is cut and hit our food,” says Lieberman.

“the processed food out of the mouth using stone tools and then by cooking played a very important role in human evolution as it released large faces and large teeth, which in turn enabled faces shorter that were important for speech and the development of larger brains and larger bodies. In part, we are what we are because we chew less. “

AGENCY ONE