Up to dominate the Earth

Are you blood-sick? Have you ever fainted with anger? Have you ever been stunned by something? The same question you ask animals, the answer is almost always "never", most animals are stunned, but not faint.

When a horror movie suddenly appears with frightening images or encounters danger, our blood pressure will soar, blood rushes to the brain, the brain will mobilize the body to let us find the moment of danger, the fire is in full swing, resourcefulness, and alertness to the highest state of the body, showing the amazing potential, animals are also.

For example, some animals are panicked in their hearts when they encounter danger, but will instinctively blow up and arch their bodies on tiptoe to make themselves look not at all wimpy. However, in extreme fear, humans can be stunned, or stimulated by something to lose consciousness.

The mechanism of fainting

Neither animals nor humans can stay on fire for long, because high blood pressure can lead to burst pipes. After high pressure, the body will sometimes "overcompensate" for blood pressure, just like a big rise is bound to be followed by a bigger drop to meet the leeks.

Overcompensation can cause blood pressure to drop to a lower level than usual, and the blood supply to the brain is even lower than usual. In eerie movie scenes, the voltage is disturbed by the magnetic field of "something" and the light bulb always flickers. Blood pressure and voltage, as well as the brain because of unstable blood supply intermittent strikes, so that consciousness and control are completely lost so that people faint on the ground.

Although animals often fall, it is mainly a muscle problem", humans are the only animals that can be so scared that they lose consciousness and do "I faint", not just "I fall".

Why are we so timid?

The most shining features of humans are upright walking and huge brain capacity, and fainting comes from the combination of these two features.

Walking upright, legs must be thick

The evolution of upright walking has placed the human brain above the heart, which pumps blood to the brain to overcome gravity. At the same time upright walking so that the original limb support evolved into two-legged support, but also to ensure that run fast enough (and not eaten by wild animals), so the human legs proportion more thick and developed than other animals, covered with a large number of blood vessels, sharing a large amount of blood in the body.

If you only give blood to the thighs, you will also die of lack of blood, because the blood of the thighs is not the thighs alone, need the whole body circulation. The legs are further away from the heart and need to overcome more gravity and travel more miles when returning.

In short, the amount below is difficult to collect, uploading the amount of effort to be large, so the brain is usually stretched to supply blood. Many people bend the delivery channel (cervical vertebrae) every day to look at the computer, look at the phone, or the body a little wind, the brain's blood will not be enough, it will issue a "headache" warning, not to mention the occurrence of transition compensation, downtime is easy to appear.

Why giraffes do not faint

Speaking of which, someone may have to say: giraffes say no! Height of 6 meters, neck length of 2 meters, found a group of lions pounced on how not directly fainted over it?

Don't look at the giraffe's neck is long, but the cervical vertebrae and humans are the same 7, but each piece is much larger than humans. By the same token, giraffes have a heart 60 times larger than humans, so they can pump blood to the brain above the canopy. Usually, giraffe blood pressure values can reach 300mmHg (human 90-140mmHg), in our view giraffes are all high blood pressure burst tables.

Maybe you have questions again: why humans have not evolved a more powerful heart? After all, from an evolutionary point of view, fainting is the equivalent of feeding other predators, and weak hearts should be eliminated and strong ones kept.

Bigger brains, bigger needs

Heart size is the result of a long bonding with the animal in nature. If you have the heart of a lion, and the size and blood vessels of all parameters do not match the "power" of the heart, it is easy to burst the tube, only to sit in a wheelchair in the shape of "6 + 7".

The human heart to cope with this small body enough but compared to the body structure of other animals, the human brain proportion is too large, the larger the brain means that more blood is needed to maintain. Although some animals such as giraffes and human brains are much higher than the heart, no animal brain is like the human brain is "bloodthirsty".

Our close relative, the chimpanzee brain requires blood flow accounting for 7% of the whole body, the brain of smaller animals, the proportion of even less than 1%, while humans reached 20%. Therefore, when the animal occurs compensation mechanism, even if the blood pressure drops significantly, the blood supply to the brain is very adequate, only the usual brain is not quite enough for the human will have a blood supply cut-off phenomenon.

Therefore, the combination of two human characteristics leads to the fact that some people will look at the blood and pass out. The good thing is that overcompensation is short-lived, the body down can also be seen as a protective mechanism for the brain, because the human body will lie down after the brain and the heart to maintain the same level of height, so that the blood will quickly back to the brain, as long as not immediately eaten by the beast, we can all quickly recover from the world of non-black or white.

Summing up

Although walking upright and having a larger brain capacity makes humans the only animal that will faint, but also the combination of these two causes fear but let humans thrive and spread around the world, sometimes the tiny black spot will be covered by a larger flash, so nature did not eliminate it, or: world domination is for the faint of heart.