As you know, the human brain is large enough when compared with other animal species. However, not all people have the same brain size, and American researchers have tried to find out why.
They found eight genetic variations responsible for the size of key regions of the brain.
These variations can represent the genetic essence of a person. New results were obtained thanks to the ENIGMA (Enhancing Neuro Imaging Genetics through Meta-Analysis) project, in which about 300 scientists from 33 countries took part.
They studied the MRI results of 30/717 people, correlated them with genetic and other information. Only by joining forces has it become possible to track down subtle genetic factors that influence brain size that have eluded discovery in smaller studies, the researchers note.
“In the end, we were able to identify so-called 'hot spots' in the genome that affect the structure of the brain,” says Paul Thompson, a neuroscientist at the University of Southern California.
During the analysis, Thompson and his colleagues looked for minute changes (one nucleotide base) in DNA that match the size of key areas of the brain. One area, the hippocampus, stores memories and aids in learning. Another structure, called the caudate nucleus, allows you to ride a bicycle, play musical instruments, or drive a car without thinking about it. The third, putamen or shell, controls the movement of the body and is responsible for motivation. At the same time, the researchers did not study the new cortex or neocortex, which helps to think or communicate - in many animals, unlike humans, this part of the brain is in an underdeveloped state.
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Thompson believes there is a strong relationship between the size of many of these parts of the brain and overall cognitive ability: the more brain tissue, the better. Many diseases damage parts of the body: Alzheimer's disease, for example, affects the hippocampus, and Parkinson's disease affects the shell.
The team found eight genetic differences that can affect brain tissue size up to 1.5%. Some of the variations were contained within a gene, and some were driven by a number of key genes.
The most influential gene turned out to be KTN1, which directs the brain cells in the shell. Two additional genes in the shell are linked to genes that can lead to colon cancer and seem to regulate the number of cells in this area of the brain. The other five genes are responsible for various things - for example, preventing programmed cell death, a natural process that can shrink an area of the brain in the event of an uncontrolled flow.
Many of the eight genes are active during the development of the brain and can influence the development of neuropsychiatric disorders, such as autism, depression, or schizophrenia. In the future, scientists hope to trace the connection between the size of a specific area of the brain and similar diseases. The discovery could also lead to the development of new therapies for the treatment of various neurological disorders, ENIGMA participants believe.
Scientists investigate and determine the ratio of the brain volume to the body volume of living beings on Earth. They also found out which animal has the heaviest brain. It is known that among people there are champions in brain weight.
Which Animal Has The Largest Brain?
Comparing the ratio of brain mass to body mass, it turned out that among vertebrates the hummingbird ranks first. For this bird, this ratio is 1 / 12. It would be possible to determine the ratio among invertebrates, however, as such, they do not have a brain, but there are nerve nodes or ganglia. If we calculate the ratio by comparing the mass of the nerve endings with the body mass of invertebrates, it turns out that the ant is the record holder. Its ratio is equal to 1/4.
If a person had a ratio of 1/4, like an ant, the head would weigh at least twenty kilograms, and would be about eight times more. However, the ant's brain is forty thousand times smaller than the human brain when comparing the number of cells of which it is made. Scientists have conducted research and experimentation to see if an ant has a mind. It turned out that these miniature insects are able to generalize and synthesize information received by them.
The record holder among all living things on the planet in terms of brain weight is the whale Physeter Macrocephalus. The brain of this animal can reach nine kilograms. However, if you calculate the ratio of the brain to the body, you get 1 / 40,000. The weight of a whale's brain depends on its age and species. It is known that the blue whale is much larger than the sperm whale, but its brain is smaller and weighs only six kilograms eight hundred grams. Another owner of a large brain is the northern beluga dolphin. His brain weighs two kilograms three hundred and fifty grams, while the bottlenose dolphin weighs only one kilogram seven hundred thirty-five grams.
The largest human brain
The weight of the human brain depends on many factors. First, the male brain is larger than the female by about one hundred to one hundred and fifty grams. There is no significant difference in brain weight between races.
Our ancestors had a much smaller brain than ours. Weight changed significantly when the first primitive man appeared. The brain of Pithecanthropus did not exceed nine hundred cubic centimeters, and the brain of Sinanthropus was about one thousand two hundred and twenty-five cubic centimeters, thus catching up with the brain of a modern woman.
It is known that Cro-Magnons possessed a brain, the volume of which is one thousand eight hundred and eighty cubic centimeters. Today the brain of a European is about one thousand four hundred and forty-six cubic centimeters. It can be concluded that every two hundred years, the brain "dried out" by one cubic centimeter. Hopefully, the decrease in volume does not lead to a drop in intelligence, but is caused by an improvement in design.
It is known that Ivan Sergeevich Turgenev's brain weight turned out to be equal to two kilograms and twelve grams. His brain could be considered the largest, however, the heaviest brain - 2850 g - was found in an individual who suffered from epilepsy and idiocy. His brain was functionally defective. Therefore, there is no direct relationship between the mass of the brain and the mental abilities of an individual individual.
Who has the smallest brain
Have you ever wondered which animal has the smallest brain? This question is ambiguous. Of the moving creatures on Earth, flatworms-nematodes have the smallest brain in weight, it weighs only a few microns. But they probably don't really need him.
However, worms still cannot be called animals. As for these particular representatives of the fauna, the koala prevails in proportion. Her brain is slightly larger than a walnut.
But if we talk about weight, this truly vital organ, then it should be said about the pygmy shrew from the family of shrews.
Her brain weighs between 1.5 and 3 mg. Just do not immediately consider her stupid. The fact is that she herself weighs only nothing - her weight is from 1.5 to 3 g. It turns out that her brain occupies 1/10 of the body. Which living creature can boast of such proportions?