Traces of evolution in us

  Grasping reflex
  baby especially love grip. When placing a finger or object in the baby’s palm, the baby’s first reaction must be to try to grasp it, and the grasping force is still very strong. According to medical research in 1932, 37% of newborns can hold a stick to support their weight and hang for a while.
  The reason why babies have this kind of grasping reflex has to mention our ancient ancestors-primates. Unlike humans with fine skin and sparse hair, primates have enough body hair for their young to cling. In this way, when encountering a predator, the cubs only need to grasp the hair on their parents, and the parents do not need to hold them with their hands. They will move more agilely and climb more flexibly.
  Nowadays, human babies are naturally free from the dangerous situations encountered at birth, but the grasping response, as a behavioral habit of humans in the evolutionary history, has become a newborn unconditional reflex and has been preserved.
  Most people get excited when cold or fear, hairs below the skin called a hair shaft muscle contraction of small muscles, hairs erect, raised layers of dots, a “chicken skin.”
  Why do we get goose bumps when we encounter irritant reactions? This is actually a legacy of human ancestors. With goose bumps, the ancestors can both defend and keep warm. When the goose bumps appear, the hairs attached to it will stand up, making the hairy human ancestors taller in the eyes of the predator, thus frightening the opponent in aura; and when it is cold, the goose bumps will act as an “insulator “, insulates the heat from dissipating and plays a role in keeping warm.
  Today, “limao” is still a useful defense method for many animals, such as angry porcupines or desperate cats. When confronted with danger, they will “rise up” and frighten the enemy. After humans got rid of most of their body hair, goose bumps are now only retained as an emotional response.
  In “Journey to the West”, Zhu Bajie often moved his big ears when eavesdropping on other people’s conversations; when Brother Monkey turned into a mosquito biting him, he would also move his ears to try to drive away the mosquitoes. Humans can actually move their ears very early. Now, most monkeys have more developed ears than humans, so they can move their ears to better understand potential threats from the outside world.
  But in the process of evolution, humans and other primates, such as orangutans and chimpanzees, slowly degraded the function of ear movement, making them lose the ability to move their ears alone.
  The external structure of the ear also reveals some traces of evolution. In the world, about 10% of the population has a spiral shape on the outer edge of the ear, which is a common feature of many mammals.
  Although humans cannot move their ears, another feature of humans makes up for this functional defect-people can move their heads horizontally, which most monkeys do not have. And among human beings, there are some ear muscle mutations who can move their ears in all directions.
  burp, these may be the oldest traces of human evolution the remains, because it implies that we have some kind of contact with the amphibians.
  When amphibians such as tadpoles are underwater, they close their glottis and squeeze their mouths, and inhale air through their gills. This simple motion reflex is similar to the principle of burping in mammals. During the hiccup, mammals close the glottis with their “old” muscles and inhale quickly. In the early stages of human embryonic development, when a healthy lung has not yet developed, babies often exercise their lung breathing by swallowing amniotic fluid and burping.
  Reenactmentists believe that hiccups evolved before lung breathing. This may explain why premature babies spend 2.5% of their time hiccups, because their lungs are not fully formed, and they need to use hiccups to breathe air like an amphibian inhale with their gills.