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Biology Evolution human body

New microevolutinary change :Median artery in the human forearm

The median artery is the main vessel that supplies blood to the forearm and hand, when first formed in the mother’s womb, but it disappears once two arteries seen in adults develop.

The radial and ulnar arteries usually replace the median artery during developmental stages in the womb, so most adults obviously don’t have a median artery, but increasing numbers of cases retain it, so a person can have all three arteries.

The median artery is now present in about 35% of people and researchers predict that people born 80 years from now will all carry a median artery if the trend continues.

“The median artery offers benefits because it increases overall blood supply and can be used as a replacement in surgical procedures in other parts of the human body,” said senior author Professor Maciej Henneberg, a researcher in the Biological Anthropology and Comparative Anatomy Research Unit at the University of Adelaide and the Institute of Evolutionary Medicine at the University of Zurich.

“This is microevolution in modern humans and the median artery 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.”

In the study, Professor Henneberg and colleagues aimed to investigate the prevalence of persistent median arteries in postnatal humans over the last 250 years and to test the hypothesis that a secular trend of increase in its prevalence has occurred.

They found a total of 26 median arteries in 78 upper limbs (a prevalence rate of 33.3%) obtained from Australians aged 51 to 101 years.

“Our study into the prevalence of the artery over generations shows that modern humans are evolving at a faster rate than at any point in the past 250 years,” said lead author Dr. Teghan Lucas, a researcher in the Department of Archaeology at Flinders University and the School of Medical Sciences at the University of New South Wales.

“Since the 18th century, anatomists have been studying the prevalence of this artery in adults and our study shows it’s clearly increasing.”

“The prevalence was around 10% in people born in the mid-1880s compared to 30% in those born in the late 20th century, so that’s a significant increase in a fairly short period of time, when it comes to evolution.”

“This increase could have resulted from mutations of genes involved in median artery development or health problems in mothers during pregnancy, or both actually,” he added.

“If this trend continues, a majority of people will have median artery of the forearm by 2100.”

“When the median artery prevalence reaches 50% or more, it should not be considered as a variant, but as a normal human structure,” the authors said.

Lucas.et al. find that the prevalence of the persistent median artery in postnatal life approximately tripled over the last 125 years.

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Biology Evolution

Should evolution be equated with ‘progress’???

Evolution should neither be equated with progress nor with the elimination of older, less efficient species. Continuation of old species depends upon the environment. The new species may or may not be better. Formation of new species depends upon the occurrence of physical or reproductive barriers, genetic drift and natural selection that leads to the formation of new population or species which is unable to interbreed with the original population.

In fact, there is no real ‘progress’ in the idea of evolution. Evolution is ‘simply the generation of diversity and the shaping of the diversity by environmental selection’. The only progressive trend in evolution seems to be that more and more complex body designs have emerged over time. However, again, it is not as if the older designs are inefficient. Many of the older and simpler designs still survive. In fact, one of the simplest life forms – bacteria – in-habitat the most inhospitable habitats like hot springs, deep – sea thermal vents and the ice in Antarctica. In other words, human beings are not the pinnacle of evolution, but simply yet another species in the teeming spectrum of evolving life.

Thus, there is no such thing as ladder of progress but there are branches from the family tree of species.