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Microevolution Part II

Microevolution Part One focused on changes in anatomy that we — Homo Sapiens — have undergone in the past couple thousand years.


Part Two will focus on the changes that are happening now, with an eye towards the future.



ARMS


Authors of a Flinders University study dissected 78 limbs of deceased adults over the age of 50 in Australia. Twenty-six of these limbs had a median artery, making for a prevalence rate of 33.3 percent. This compares to a 10 percent rate present in a population recorded in the late 1800’s.


Median arteries are for babies. No, seriously! From gestation they occur in the developmental stages of the womb, before being replaced by the radial and ulnar arteries. These are the two main arteries in adults that carry blood to the forearm and hand.


Now, however, they are sticking around in our arms. At this rate, by 2100 the human arm could have three main arteries, instead of two. While the evolutionary benefits are still unclear, the senior author of the study suggests that the benefit of an added vessel means increased blood supply.


JAWS


Wisdom teeth are biological oddities. They lay dormant for years, and suddenly erupt, long after their fellow oral companions have already formed. Or they don’t appear at all. Or they grow impacted: crunched for space, they go off any which way, looking for real estate.


Well, the children of the future may not know what it is like to have a week-long liquids-only diet after a wisdom tooth operation. According to the same study, humans are now increasingly born with smaller jaws.


In a trend that started with the agricultural revolution 12,000 years ago up to our present-day teeth-friendly food menu of Strawberry Spinach smoothies or Big Macs, our calories come easier. Our mouths have responded by shrinking (or rather, not developing to their full potential)—leaving less space for tooth formation.


A graphic shows a comparison of the mandible of our ancestors. The mandible of Homo Sapiens is furthest on the right. This article points to several studies that discuss the fascinating correlation of diet and wisdom teeth growth.


BRAINS


Since Darwin, it is thought that natural selection + DNA + thousands of years = Evolution. Technology has changed that.


Modern medicine has made certain maladies more livable. Take surgery for impacted wisdom teeth, for example. Or chemotherapy for cancer patients. Or respirators for COVID-19 patients. It is not hard to imagine what our health as a species would look like sans these technological tools, with natural selection operating unfettered.


Now, DNA has come to represent a mere first draft that technology can tweak, edit, and yes—evolve.


Take Neil Harbisson for example. Harbisson has achromatopsia—he can’t see color. So he decided to become a cyborg.


The antenna anchors in the back of his skull and arcs forward, ending in a fiber-optic sensor that dangles between his eyes. The sensor relays color, in the form of sound frequencies, to a microchip implanted in the back of his head.


Harbisson feels color, infrared sensors, down to the ultraviolet markings at the center of a flower that signify its nectar. “He has not just matched ordinary human skills; he has exceeded them” writes DT M