Why can't we reach 3 meters tall?

Although accounting for 70% to 80% of the results, the human genome is not the only factor determining height.

You may have wondered why there are families with a height as high as basketball players, while others are only at a relative level like athletes or wrestling. In the group you will also have a significant height difference, the tallest guy will be comfortable taking "selfies" , while the youngest struggles only to squeeze into the frame.

Despite such a significant height difference, the height limit of humans is actually only average: In the United States, a healthy man has an average height of about 1m75, in women are about 1m63. We know that children will inherit the height-regulating gene from their parents , but why do most people fall within a certain standard range that cannot be as tall as 3 meters?

Why can't people never stop being tall?

Human height is not limited only to the outer stature.

In fact, we have to thank the evolutionary achievements, too, according to Terence D. Capellin, a biologist who studies human evolution at Harvard." The height of a human is not only externally expressed. It also represents the overall biological development of each organism, but humans are an example , " Capellin said. The researchers speculate that the height of the human being is not the separate effect of the extremely complex genome, but instead interwoven with other growth processes, such as the development of viscera. Over millions of years, the natural selection process has been painstakingly "honing" the details of the human genome and gradually affecting the development of the body and organs through the proliferation of genes. connective tissue and adjacent tissue generations. Therefore, our height is simply an accompanying development process.

In addition to genetic factors, other environmental factors such as proper nutrition and modern healthcare methods also affect height development, but gene codes still play a very important role. important, accounting for 70% to 80% of results. Human height often grows rapidly during puberty, which is the time when evolutionary mechanisms are involved in the body's development. When the body height reaches a predetermined limit, a biological mechanism like "aging programming" will be in charge of neutralizing the genes responsible for growth. Most of us will grow taller until the end of puberty, during which the bone will be continuously stretched. This process occurs in growth cartilage, two layers of cartilage located on the two vertebrae and the long bones of children, such as the femur and tibia.

Jeffrey Baron, a pediatrician and head of growth and development research at the US National Institutes of Health, says that "we grow fastest in the fetus" . After that, the growth rate will decrease. In fact, the fetus grows about 20 times faster than a 5-year-old child. The cartilage tissue that grows in mitotic babies is very strong, causing them to grow quickly. As children get older, the cartilage layers also grow slower. Finally, from the middle to the late teen years, the growth of cartilage growth ceases and we reach adulthood.

Compare the growth of the body with a toy train train. "The coiled train's coil springs will store a source of energy, and when released, the train will charge forward and then slowly stop once the spring is fully stretched out, " Baron said . When we use up our pre-programmed genetic growth potential, like the spring, our growth is slowing down and eventually stopping . "

Things that science knows and doesn't know about height genetic factors

There are many genes that affect height.

There are actually hundreds of genes capable of influencing height. A study in 2018 found more than 500 genetic codes related to this growth pattern. Those genes control the action of growth cartilage and control bone length.

"For most people, not just a gene code can make us low or high, but a collection of many different gene codes , " Baron said.

Although rare, mutations associated with height can cause abnormally high stature. André the Giant (also known as the giant André) in the movie The Princess Bride, whose pituitary gland is not working properly, produces too much growth hormone, leading to abnormal development. . In addition, there are other factors that affect height, such as bone dysplasia causing short bones and often deformities.

According to a study of the American Endocrinology Association in February 2019, excessive growth hormones also pose serious health risks, such as heart failure, bone disease and "depletion of substances." quality of life " .

By documenting the height of thousands of people in a study that correlates the entire chromosome, a method for finding genetic variations that occur frequently in groups of people with similar physical characteristics, researchers The study aimed to understand the relationship between genetic height and disease susceptibility.

Clarifying the mysterious relationship between genomes can help us change the way we treat diseases. According to a 2015 study by the New England Journal of Medicine (NEJM), genetic variations that cause short bone disease, are also at risk of developing coronary artery disease (CAD). If we can pinpoint certain genetic variants, then in the future, genomic editing techniques like CRISPR could create conditions for formulating therapies and treating disorders. new growth.

If you are hoping that one day the human body will reach a higher height, pay attention to the Nordic region. Last year, researchers concluded that people in Denmark, Finland, Norway and Sweden are getting taller with each generation.

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