Evolution is in full swing
How the human body has changed in a hundred years
Alfiya Yenikeeva
In modern people, the median artery of the hand is more common and wisdom teeth grow less often than those who lived a century ago, Australian experts have found. Other researchers have discovered new bones in the human skeleton. So, we are still evolving, scientists concluded. How exactly – in the material of RIA Novosti.
New artery
In the early stages of pregnancy, all human embryos form a median artery in the area of the future forearm. Her task is to help the blood flow through the center of the growing hands and nourish them. As a rule, by the eighth week of embryonic development, it regresses, and the radial and ulnar arteries take its place.
However, this does not always happen. Back in the middle of the XVIII century , anatomists noticed: in some people, an additional vessel functions for life. Their share in the population was estimated at no more than ten percent.
Australian scientists decided to update the information and analyzed the structure of the hands of 78 deceased men and women aged 51 to 101 years. As it turned out, over the past 25 years, an additional vessel in humans is becoming more common. Experts found it in 26 people – this is about 33.3 percent of those studied. And most of them were born after 1940.
Comparing the data obtained with the results of the previous 47 studies, the scientists came to the conclusion: the share of owners of an additional vessel has increased by 20 percent over the last century. If the trend continues, then in 80 years the majority will have it.
The mechanism of regression of the median artery in the embryo is regulated by special genes. This means that there have been changes in the work of DNA sections – this indicates that human evolution continues. In any case, the benefits of an additional vessel are greater than the harm. For example, it acts as an "emergency channel" for injuries of the ulnar or radial arteries.
Disappearing teeth
Another important sign of ongoing evolution is the absence of wisdom teeth in almost 20 percent of Europeans. Increasingly, specialists do not observe even the rudiments of these molars in patients. And if they are, they occupy the wrong position or do not erupt until the end. This fits into the general evolutionary trend and is most likely due to a change in diet, American, Australian and Scandinavian researchers note.
The fact is that the process of becoming Homo sapiens is a kind of history of tooth reduction. Our ancestors had large molars in the back of the massive jaw, which made it possible to chew solid food for a long time. About 2.6 million years ago, the diet became more diverse: meat was added to plant foods. Two million years later, people mastered fire and learned how to thermally process food. The time of chewing has been reduced significantly, the size of the jaw and teeth have decreased, and the posterior molars – those very wisdom teeth – are no longer needed at all.
This thesis scientists from Harvard University (USA) confirmed experimentally. We recruited several dozen adult volunteers and divided them into groups. Some ate meat, the second – sweet potatoes, the third – carrots and beets. The products were either not processed at all, or very little. Scientists measured how much effort the subjects put into chewing different foods.
The authors of the work calculated: the transition from root vegetables to a meat diet reduced the chewing time by 17 percent, plus 26 percent less effort is needed. Therefore, the size of the jaw and teeth of ancient people decreased. In the future, according to scientists, the posterior molars may disappear altogether as unnecessary.
The bone was found
Over the past 150 years, doctors have been almost three and a half times more likely to observe fabella in patients – a small bone that covers the knee joint from behind. It greatly interfered with our ancestors – it reduced the maneuverability and flexibility of the joint, so it was very rare.
Now, experts believe, the kneecap needed additional protection: the average height and weight of people have increased, the load has increased, and this bone is necessary.
Modern man, on average, eats better than those who lived 100-150 years ago. People are now taller and heavier – this provoked the development of longer shins and large calf muscles, which, in turn, increased pressure on the knee.
Researchers from Imperial College London (Great Britain) came to this conclusion after analyzing more than 21 thousand cases of fabella in residents of 27 countries. As it turned out, if at the beginning of the last century the bone was found in about 11.2 percent of the population, then by 2018 it was already in 39.
According to scientists, if the trend continues, then in a hundred years most people on the planet will have Fabella.
People have become colder
Another important and subtle change over the past 150 years is a decrease in body temperature. As scientists from Stanford University (USA) found, during this period people cooled down by about 0.4 degrees Celsius.
Experts analyzed data collected from 1862 to 2017, and found that since 1860, the average body temperature has decreased by 0.003-0.0043 degrees every 12 months. So, men born in the noughties of this century are 0.59 degrees colder than those who were born at the beginning of the XIX century. The temperature of modern women is 0.32 degrees Celsius lower than those born in the late XIX – early XX century. Moreover, the figures did not change even when taking into account the body mass index, height and race of the participants.
According to the authors of the work, there are several explanations here. Firstly, over the past 150 years, people in general have become healthier – thanks to the rapid development of medicine and an increase in living standards. This means that the probability of developing inflammation with an increase in temperature is lower on average than those who lived in the past and the centuries before.
Secondly, human cooling may be associated with modern amenities. Air conditioners and heating systems maintain approximately the same air temperature in the rooms all year round. As a result, the body does not need to expend additional energy for thermoregulation.
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