While speculation about future human evolution often focuses on dramatic shifts in appearance, subtle anatomical changes happening today reveal the ongoing nature of this process. A particularly intriguing example is the increasing prevalence of a persistent extra artery in our arms, a change that could become commonplace within just a few generations.
The Median Artery: A Developing Feature
During fetal development, all humans possess a median artery that runs down the center of the forearm, providing blood to the growing hands. Typically, this artery regresses around eight weeks of gestation, with its function taken over by the radial and ulnar arteries – the latter of which is the one we feel when we take a pulse. However, in some individuals, this regression doesn’t occur completely.
A Rising Prevalence Over Time
A 2020 study by researchers from Flinders University and the University of Adelaide revealed a significant increase in the number of adults retaining this extra blood vessel. Anatomists have been studying the prevalence of this artery for centuries, and the study’s findings clearly indicate an upward trend.
- In people born in the mid-1880s, this persistent artery was observed in roughly 10 percent of individuals.
- That number jumped to around 30 percent in those born towards the end of the 20th century – a substantial increase over a relatively short period.
To understand this trend better, researchers examined 80 limbs from cadavers, all donated by Australians of European descent. These donors ranged in age from 51 to 101, meaning they were largely born in the first half of the 20th century. By carefully noting the presence and health of the median artery, the research team was able to compare historical data with their findings.
What Drives This Evolutionary Shift?
The increase in the median artery’s prevalence suggests that natural selection is favoring individuals who retain this extra blood supply. But what factors are behind this selection? Researchers believe several possibilities could be at play:
- Genetic Mutations: Mutations in genes that govern median artery development could be contributing to its persistence.
- Maternal Health Issues: Problems experienced by mothers during pregnancy might also be a factor. It’s likely that both genetic and environmental influences are involved.
The advantages of having a persistent median artery are not fully understood. While it could potentially enhance dexterity and forearm strength, it also carries an increased risk of developing carpal tunnel syndrome – a condition that limits hand function.
Implications for the Future
The rapid rise of the median artery mirrors a similar trend observed with the fabella, a knee bone that has become three times more common in the past century. These seemingly minor changes, known as microevolutionary changes, accumulate over time, leading to larger-scale variations within a species. As the trend continues, researchers predict that a majority of people will possess a median artery of the forearm by the year 2100.
This ongoing evolution underscores the dynamic nature of the human body and the continuous interplay between genetics, environment, and health. It raises intriguing questions about the future of human anatomy and the unexpected ways we continue to adapt.
This research was published in the Journal of Anatomy.>
