Our ancestors inability to chew meat helped us make who we are today.
Today we thoroughly enjoy our meals and spend very little time and physical effort chewing them. Maybe we should thank our ancestors for improving our chewing ability because the methods that our ancestors used for eating food helped us make who we are today.
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A new study has found that around 2 to 3 million years ago early modern humans started to eat meat and used simple stone tools to process their food. Researchers estimate that such a technique would have made food easier to consume and gave our ancestors more free time and energy to rise above the rest of animal kingdom and made possible further changes that helped us make human.
Our closest relatives, chimps, spend almost half of their day chewing food and also with greater force. The inclusion of meat in diet and invention of stone cutting tools may have been a great turning point in human evolution and paved the way for less need of chewing food.
“Chewing is one of the key characteristics of being a mammal. Most other animals, like reptiles, barely chew their food -- they just swallow it whole. The evolution of the ability to chew food into smaller particles gave mammals a big boost of extra energy because smaller particles have a higher surface area to volume ratio, allowing digestive enzymes to then break food down more efficiently.” Co-author Lieberman who is professor of Human Evolutionary Biology at Harvard University explained in a statement.
One of the biggest mysteries in human evolution is how species such as Homo erectus evolved smaller teeth, jaws and chewing muscles than their predecessors. Researchers suggest that when early humans started to consume meat possibly raw meat, they didn’t have teeth well-suited to break chunks of the meat and swallow it.
By processing food –slicing meat and pounding vegetables – before eating, humans not only decrease the effort needed to chew food but also started to chew it more effectively.
“Eating meat and using stone tools to process food apparently made possible key reductions in the jaws, teeth and chewing muscles that occurred during human evolution,” said lead author Katie Zink.
To test this idea, researchers have to conduct a bit stomach-churning experiment. They asked volunteers to chew raw and cooked meat as well as several vegetables. When they chew it enough, they had to spit out the food so it can be analyzed. Researchers also attached instruments to the subject’s jaws to measure the effort involved in chewing.
Researchers found that humans cannot eat raw meat effectively but once they process it even just slice it, it affects chewing performance dramatically.
“Meat has a lot of nutrients, but it is also very elastic,” said Zink. “You can think of it as being like a rubber band. So the problem is that we can’t break it down with our flat, law cusped teeth. But if you slice it up, then you do not need to use your teeth to break it down as much and you swallow much smaller particles. Cooking makes chewing even easier.”