Why is the Giraffe not dizzy?

With its "oversized" long neck, giraffes become one of the tallest animals in the world. In just 1 or 2 seconds, a giraffe can lift its head from the ground to a height of about 4.5 meters without ever being stunned.

The cause of the Giraffe is not dizzy?

" If we do that, of course we will be dizzy , " said physiologist Graham Mitchell of the University of Wyoming.

When a giraffe raises its head, the blood vessels on its head will shift almost all blood to the brain

Experimental Biology magazine in early July, Mitchell and his team said that a healthy, healthy heart and high blood pressure will keep giraffes from falling into this state of shock.

How does it work?

Blood will flow to the giraffe's head as it bows its head to the ground and blood pressure will double. When the animal raises its head to nibble on the leaves of the blood tree, it quickly withdraws.

This is the same for us. You may feel unsure if you hang yourself upside down and your face will turn red, you quickly turn yourself upside down. If your blood pressure is too low, not enough blood to flow to your brain, you may be unconscious.

With a long neck, giraffes spend most of their time moving their heads from low to high and so they need to take measures to keep blood flowing to the brain so they don't get dizzy.

Scientists once thought that giraffe's blood vessels help guide blood from the heart to the brain. However, Mitchell's research shows that they use a very powerful pump to bring blood to their brains and blood pressure twice as high as we do.

Heart weighs nearly 12kg

Giraffes have a very large heart, they weigh about 12kg. When a giraffe raises its head, blood vessels on its head will move almost all blood to the brain without going to other parts of the head like cheeks, tongue or skin.

At the same time its thick skin and a strange muscle vein in the veins - veins often do not have muscle - will add blood pressure to the veins so that the veins can carry blood from the head back to the heart.

"It is a much more advanced anti-stunner mechanism than we do ." Mitchell said.

Blood will flow to the giraffe's head as it bows its head to the ground and blood pressure will double

Why do giraffes have such high necks?

While other family members have long necks, only Okapi Central Africa has a short neck.

Like humans, giraffes have 7 neck vertebrae. So why are they so tall? The answer lies in their third neck vertebrae . The giraffe's C3 burn is 9 times longer than its width. This length is equivalent to the arm bone connecting the shoulder to the human elbow.

According to a published study by Royal Society Open Science, the extension of the third neck vertebrae in giraffes occurred in two stages. This vertebrae of them has extended forward about 7 million years ago and then in the opposite direction after 6 million years.

The cause of this process is still in discussion. Some scientists argue that it is an evolutionary process to get higher leaf clusters. Others say that it is the result of the process of fighting or sex selection.

Recently, a new research direction was opened at Osteopathic Medicine School, New York Institute of Technology, led by Melinda Danowitz. To answer this question, the research team analyzed and compared 71 vertebrae of 11 species in the family of giraffes. 9 of them are extinct and only 2 species survive. Work is done based on data mining and specimens in museums around the world.

'We discovered a very unexpected fact,' said Nikos Solounias, a research co-author from the New York Institute of Technology.'First, only the front part of C3 vertebrae is prolonged. This appears on some species. Next is stage 2, when the vertebrae is extended towards the tail. Modern giraffes are the only species that appears to stage 2 of the process. That's why it has a considerable long neck. '

C3 of Samotherium vertebrae and modern giraffes 7 million years ago.

The extension of the neck vertebrae forward takes place about 7 million years ago. Evidence of it is recorded on a number of species such as Samotherium, relatives of giraffes today. The second phase only happened about 1 million years ago. And until then only giraffes underwent this process.

Besides, the team also discovered an interesting fact that giraffes are not the first species to stretch their necks. Danowitz said ' An ancestral species called Prodremotherium even lasted about 16 million years ago .' This indicates that the neck length is no longer a valid attribute to identify the family of deer.

A branch of giraffe family.

Another interesting thing, while other family members have long necks, only the Okapi Central Africa has a short neck.

In a study published in Nature Communications on May 17, the scientists compared the giraffe's genome to the Okapi , their closest relative. The purpose of the study is to identify specific genes, related to the evolutionary origin of giraffes and special traits including long necks, high-speed running (60 km / h), and Complex cardiovascular system.

" The evolutionary process of creating a giant giraffe's appearance as well as transforming the body helps them to run at high speeds and strong cardiovascular activity is a mystery to the scientific world since the 1800s, when Charles Darwin first explained the evolutionary origin of giraffes , "said Douglas Cavener, research author at the University of Pennsylvania, USA.

Okapi is the closest relative to giraffes.(Photo: Flickr).

Research results show that giraffes and Okapi developed in two different directions from a common ancestor 11-12 million years ago. Scientists also identified 70 genes of giraffes that carry many signs of adaptation to the environment. Half of these 70 genes encode into proteins , thereby affecting the physiological development and function of the bone, cardiovascular, and nervous system.

"The giraffes and neck bones of giraffes have evolved a lot to lengthen. There are at least two genes involved in this process, a gene that determines the area of ​​bone to develop and other genes that stimulate bone growth. "The idea is," Cavener said.

The team successfully identified the above genes. One of these is called FGFRL1 gene , which plays an important role in controlling development, starting from the embryonic stage until the long bone phase, after the giraffe is born.