It helps shield the opening of the urethra from any contaminates or bacteria, explains Weinhaus. Quicklist: 7category: 7 'Useless' Body Parts Explainedtitle: Foreskinurl:text: Male foreskin takes years to separate from the glans (head), which is unusual enough of a process to suggest one if its main functions may help prevent infection, especially in infants.
THE STORY OF THE HUMAN BODY BY DANIEL LIEBERMAN INTRODUCTION EXPLANATION FULL
Since humans now eat soft, cooked foods as children, our jaws don’t grow to the full capacity.
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Jaws are bone and, like the rest of your body, need to be supported and used in order to grow properly. They’re grown before you use them, and then they erupt to the surface,” says Lieberman. Until recently, wisdom teeth were never an issue for humans. Quicklist: 6category: 7 'Useless' Body Parts Explainedtitle: Wisdom Teethurl:text: Like monkeys, men have three permanent sets of molars. How Inspecting Your Tongue Can Detect Serious Issues in Your Mouth and Body Your lymph nodes are incredibly important, but there's some redundancy, so if a pair is taken away, you can survive without them, Lieberman adds. Sometimes your tonsils get inflamed and infected, which is when they're removed. “Your oral cavity is an entryway to your body, so immune cells in your throat can help you fight respiratory infections,” Lieberman explains. Quicklist: 5category: 7 'Useless' Body Parts Explainedtitle: Tonsilsurl:text: Tonsils are technically lymph nodes-part of the lymphatic system, which is vital to your immunity. “Your microbiome is very important to digestive tract function, so this reservoir would allow microbes to recolonize your gut after inflammation or digestive issues,” he explains. Recent research, though, suggests the appendix might be an essential hangout spot for healthy bacteria. Since humans stopped eating uncooked or low-quality foods like grass, this chamber is no longer useful. “One idea is the human appendix is remnant of what used to be a larger fermenting chamber in our gut,” Lieberman says. Quicklist: 4category: 7 'Useless' Body Parts Explainedtitle: Appendixurl:text: The appendix is a vestigial organ, which means it has lost most of its ancestral function. The researchers speculate that eyebrows have remained because they’re crucial to identifying faces and navigating social circumstances.ĩ Horrible Things That Can Happen to Your Eyes
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Lieberman favors the hypothesis that eyebrows serve to communicate your emotions, but they may also communicate your identity.īehavioral neuroscientists from Massachusetts Institute of Technology found that people were less likely to recognize pictures of celebrities without their eyebrows than without their eyes. Quicklist: 3category: 7 'Useless' Body Parts Explainedtitle: Eyebrowsurl:text: The evolutionary purpose of eyebrows is debatable: In one camp, scientists believe brows keep sweat and rain off your eyes, which would help in primitive hunting and navigation. Presumably, the hair holds on to the secreted odors so they'll stay around long enough for a potential mate to catch a whiff, he explains. There are two types of sweat glands in your body: eccrine and apocrine, the latter of which are mostly in your armpits, explains Daniel Lieberman, Ph.D., professor of human evolutionary biology at Harvard University.