Why can't we be 3 meters tall?

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

You must have wondered why there are families with a great height like basketball players while others are only at a relative level like equestrian or wrestlers. In the group of friends there will also be a significant height difference, the tallest guy will comfortably take a “selfie” , while the smallest one will struggle just to squeeze into the frame.

Despite such a significant height disparity, the human height limit is actually mid-range: In the United States, the average healthy man is about 1m75, in the United States. woman is about 1m63. We know that children will inherit the gene for height from their parents , but why is it that most people are within certain limits and can’t be 3 meters tall?

Why can't we be 3 meters tall?
The height of a person is not only reflected in the outer stature.

In fact, we have to thank this evolutionary achievement, according to Terence D. Capellin, a biologist who studies human evolution at Harvard University. “A person’s height is not only reflected in the external stature. It also represents the overall biological development of each organism, of which humans are an example,” said Capellin. The researchers surmise that human height is not a separate effect of the extremely complex genome, but instead is intertwined with other growth processes, such as the development of viscera. Over millions of years, the process of natural selection has meticulously “honed” the details of the human genome and gradually influenced 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 growth process.

Besides genetic factors, other environmental factors such as proper nutrition and modern health care methods also affect height growth, but genetic codes still play a very important role. important, accounting for 70% to 80% of the results. Human height usually grows rapidly during puberty, which is the time when evolutionary mechanisms are involved in the development of the body. When body height reaches a predetermined limit, a biological mechanism like “programmed aging” will turn off the genes responsible for growth. Most of us will grow in height until the end of puberty, during which the bones will be continuously lengthened. This process occurs in the growth plates, the two layers of cartilage at the ends of the 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 during the fetal period” . After that, the growth rate will gradually decrease. In fact, fetuses grow about 20 times faster than 5-year-olds. Cartilaginous tissues in newborns divide very vigorously, causing them to grow rapidly. As children get older, the cartilage layers also slow down. Finally, from mid to late adolescence, growth plate growth ceases and we reach adult height.

Compare body growth with a toy train. Baron said, ”The coil springs in the compressed train will store a source of energy, when released the train will rush forward and then slowly stop once the spring is fully stretched. As we use up our genetically programmed growth potential, like the spring above, our growth slows down and eventually stops.”

Why can't we be 3 meters tall?
There are many genes that affect height.

There are actually hundreds of genes that can affect height. A 2018 study found more than 500 genetic codes associated with this growth pattern. Those genes code for the activity of growth cartilages and control bone length.

“For most people, it’s not just one genetic code that can make us short or tall, but a collection of many different genetic codes,” Baron said.

Although rare, genetic mutations related to height can cause unusually tall stature. Actor André the Giant (aka the giant André) in the movie The Princess Bride, has an abnormal pituitary gland, producing too much growth hormone leading to abnormal growth . In addition, there are other factors that affect height, such as skeletal dysplasia, which makes bones short and often deformed.

According to a study by the American Endocrine Society in February 2019, excessive growth hormones also carry serious health risks, such as heart failure, bone disease and “decreased quality of life”. quality of life” .

By recording the heights of thousands of people in a whole-chromosome correlation study, a way to look for genetic variations that occur frequently in groups of people who share a common physical trait, the researchers said. The study aimed to understand the link between genetic height and disease susceptibility.

Unraveling the mysterious relationship between genomes could help us change the way we treat disease. According to a 2015 study by the New England Journal of Medicine (NEJM), genetic variations that cause short bone disease are also associated with an increased risk of coronary artery disease (CAD). If we can pinpoint certain genetic variations, in the future, genome editing techniques such as CRISPR could facilitate the formulation of therapeutics and treatments for disorders. new growth.

If you are hoping for a day when the human body can reach a higher level of height, then keep an eye on the Nordic region. Last year, researchers concluded that populations in Denmark, Finland, Norway and Sweden are getting taller with each generation.