Evolution has been a natural process in every single living species since the origin of life, including humans. Scientists have discovered a way that humans are evolving today through an extra artery, blood vessels that carry oxygen from the heart to tissues, in the forearms of some people.
The study by The University of Adelaide and Flinders University was published in the October issue of the Journal of Anatomy. The prevalence of the median artery in the arm have been reported since the 18th century, wrote the authors.
For years, the median artery was associated with the early weeks of development and typically regresses after the 8th week of birth. The new study is a continuation of a study from 1995 suggesting that the increased prevalence of the median artery during the 20th century may be a global trend.
Extra Forearm Artery
During the study, 26 out of 78 Australian adults over the age of 50 had a median artery. In the 1880s, there was only about a 10% prevalence of the median artery in adults and has grown to about 30% prevalence by the 20th century.
The new study might be just one "example of microevolutionary changes in the internal anatomy of the human body," wrote the authors. Currently, the prevalence of the median artery is at 35%. The team predicts that by the year 2100, 100% of the global population will have the median artery.
Dr. Teghan Lucas said that one reason for the extra blood vessel may be the result of genetic mutations during the median artery development. Another reason may be health complications of mothers during pregnancy or a combination of both.
Dr. Maciej Henneberg explained that this sign of evolution during modern times "is a perfect example of how we're still evolving because people born more recently have a higher prevalence of this artery when compared to humans from previous generations."
Moreover, Dr. Lucas explained that we are in a relaxed state of natural selection, meaning that it does not play a major role in current evolution compared to our ancestors. "This is because we've pretty much mastered our environment."
Being in this relaxed state of natural selection also means that genetic variations are becoming less harmful. The "embryonic development is simplified and thus the artery" remains until birth and into adulthood.
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Prevalence of Wisdom Teeth
For years, scientists have been looking for signs of evolution in modern humans. Some have speculated that the wisdom teeth or last set of molars developing between the late teenage years or early twenties are part of evolution.
A 2019 study suggested that wisdom teeth existed so that people could chew hard food from the wild such as a wild game. In recent years, wisdom teeth have become impacted, shortening the jaw since modern humans have softer food.
Another study from Harvard University in 2015 determined that about 22% of people have impacted wisdom teeth while 22% of people don't have wisdom teeth. Not having wisdom teeth at all may be an example of recent evolution as the food available today may not need the use of the third molars.
Other human anatomy changes over time include the increased prevalence of a bone behind the knee joint called the fabella. The ima artery in the thyroid had also decreased over time until it disappeared completely before the 21st century.
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