By A. S. Deller | 2 February 2022
The story of humanity is a story of adaptation. Over the past 200,000 years, ever since the first modern humans (Homo sapiens) appeared in Africa, people have been spreading outward from that continent in every possible direction. As they encountered new environments and challenges, our ancestors had to change in many ways to survive.
New dangers meant that only the physically strongest or smartest humans tended to live long enough to pass on their genes.
We began our journey through evolutionary time as a species just over 200,000 years ago on the continent of Africa: Homo sapiens lived in small bands of people, hunting and gathering while fending off a deadly array of powerful predators. Sapiens existed simultaneously with Homo neanderthalensis and Homo heidelbergensis, for the most part separated by distances extending across northern Africa, the Middle East, and Europe. Often, though, the three separate subspecies would cross paths. Their differences were too much in most cases, and they likely fought over territory and ended up killing one another. But there is genetic evidence that Homo sapiens at some point interbred with Neanderthals.
Our current subspecies is known as Homo sapiens sapiens is believed to have arrived between 40,000–130,000 years ago. People crossed the seas from southeast Asia some 60,000 years ago to inhabit Australia. Sometime after 40,000 years ago, the first humans migrated across the Bering Land Bridge that connected Siberia to North America. In the ensuing millennia, those people spread outward and south, until human populations reached as far as Cape Horn in Argentina. At that point, all the Earth knew the mark of humanity, save for Antarctica.
The entire story of genus Homo on Earth is fairly well understood at this point, even though many details are still, and may never, be known. Our evolution on the planet of our birth is not finished, either. Wherever human populations converge and intermingle, we mix genetically and continue to alter the overall expression of our species. Wherever humans remain relatively untouched by this expansion, those people also continue to change over generations based on the environmental and societal pressures exerted on them.
According to the paper, Physiological and Genetic Adaptations to Diving in Sea Nomads, published in April 2018, the Bajau (sea nomad) people of Southeast Asia are a modern example of evolution-in-action. Their subsistence lifestyle is based around diving to depths of 200 feet or more underwater to harvest fish and shellfish. They live in stilt-huts along coastal waters, hundreds of thousands of them in fairly isolated communities in Malaysia, the Philippines, and Indonesia.
Hey Seattleites, today I'm hosting Melissa Ilardo for the first @uwgenome seminar of the decade! Come to Foege auditorium at 3:30 PM for a deep dive into genetic adaptations in southeast Asian sea Nomad populations https://t.co/TvIKYPkRtO
— Kelley Harris (@Kelley__Harris) January 8, 2020
The researchers discovered numerous physical differences between the Bajau people and indigenous folk who live inland.
Using a comparative genomic study, we show that natural selection on genetic variants in the PDE10A gene have increased spleen size in the Bajau, providing them with a larger reservoir of oxygenated red blood cells. We also find evidence of strong selection specific to the Bajau on BDKRB2, a gene affecting the human diving reflex.
This is among the most recent evidence that human populations on Earth are still evolving.
In the paper titled Human High-Altitude Adaptation: Forward Genetics Meets the HIF Pathway, the authors write, regarding populations of people who live in the high altitude regions of the Tibetan Plateau, the Andean Altiplano, and the Semien Plateau of Ethiopia:
Intriguingly, genetic signatures in genes of the hypoxia-inducible factor (HIF) pathway, the central pathway that transduces changes in oxygen tension to changes in gene expression, have been identified (Kaelin and Ratcliffe 2008; Lendahl et al. 2009; Majmundar et al. 2010; Semenza 2012). This suggests that in indigenous high-altitude populations, selection for adaptation to chronic hypoxia (as opposed to cold, increased UV irradiation, or some other environmental stress experienced at high altitude) is a key component of their recent human evolution.
Even as small, isolated populations still continue to evolve on their own, the majority of Earth’s population is experiencing something of an opposite effect. The expanded ability of most people to communicate with one another and move across borders and oceans has been leading to an unprecedented intermixing among our species over the past 100+ years.
Right now, most of humanity can be grouped into specific genetic clusters of people most closely related to one another, with names such as Siberian, North Amerindian, Tropical West African, Polynesian, and about 20 others.
These populations evolved over time as people migrated from place to place in search of new resources.
The evolution on display in our modern world is actually of two types: Evolution caused by specialization in isolated populations, and evolution driven by selective breeding. The second type is what will determine humanity’s near-future course.
By “selective breeding”, I refer strictly to the power that social stratification has upon society. Though at this point it has been proven that genetic traits do not determine a person’s class standing, something of an opposite effect is happening due to the continually growing gap between rich and poor. Just as throughout all of history, people in the highest status of a society tend to mate and produce offspring, while those of lower status mate within their class. While in the past the wealthiest classes tended to be quite small and isolated, in our modern world the sheer numbers of the wealthy classes are much larger (though the overall % remains rather small), and they are much more mobile.
This is a rather recent phenomenon, occurring mainly since ~1900, but the results are already visible: The rich already display genetic tendencies greater than the general population toward slightly higher fitness potential and physical attractiveness. This is caused by our modern culture which values these traits to such a degree that people who reach the peak of careers reliant on such traits are rewarded handsomely, propelled into the upper class. While many of the upper classes are born into their status and remain there due to inheritance — which was, until the 20th century, the only real way to get there — that same portion of society is now mixing with a new group of “genetically superior” celebrity-class individuals.
This genetic class stratification will be further compounded within this century by the wealthy’s ability to afford medical procedures that ensure, and even allow the choice of, their offspring’s traits: the upcoming trend of “designer babies”. The advent of easier gene-editing techniques heralded by CRISPR/Cas-9 will bring about an era of pre-conceptive modification of the human body. Not only will those who can afford this technology be able to ensure their children are free of hereditary diseases — they will also be able to control how their children look. Soon, the children of the wealthy will be born with a base level of physical fitness, attractiveness, and intelligence that automatically places them in the top 1% of the human race.
Genetic engineering probably won’t become very widespread until after a period in which a large percentage of the population is enhanced in the traditional sense of engineering: melding the human body with mechanical and computer technology. Companies like Neuralink are making headway in designing brain-computer interfaces, and prosthetic technology is advancing at an ever-increasing rate. The idea of the “cyborg” as envisioned in science fiction of the mid-to-late 20th century is about to become reality.
In the next 100+ years, we will very likely see these genetically and cybernetically enhanced humans in sporting arenas, on battlefields, and in law enforcement, and living and working in exceedingly harsh climates — including space.
Further out, in the 10–100 thousand year range from now, the processes that drive human evolution will come full circle, in a way, as our species once again split into innumerable different groups during our time of colonizing the Solar System and exoplanets of other nearby stars. Living on worlds with significantly higher or lower gravitational pull than Earth will eventually transform the standard human body, as will the varied atmospheres, pressures, and exposure to different degrees of cosmic and solar radiation.
For instance, a world with higher gravity would spur the evolution of people to favour physical traits that include a stronger, denser skeletal system and a more powerful cardiovascular system to pump blood against a more intense downward pull.
Physical evolution is no longer tied completely to how our bodies might react on their own. The idea of transhumanism holds that we — and the machines we create and the artificial intelligence that grows out of our technology — will direct our evolution. We already incorporate a variety of technology into the bodies of people who have physical or mental impairments. We are on the cusp of implanting such technology for the entirely different purpose of enhancing our performance. Imagine having the full capacity and power of an internet-connected supercomputer plugged directly into your brain, nanomachines in your blood that increase your oxygenation and athletic performance, or eyes that can see every wavelength of light.
In one million years, Home sapiens, the modern subspecies of Homo sapiens to which we all belong, will no longer exist as such. There may be new subspecies living on worlds separated by tens of millions of miles and even light-years: Homo sapiens Martis, Homo sapiens Titanus, Homo sapiens Centaurium, etc. Or perhaps these will be completely new species by that point, unable to interbreed.
And lastly, there is the concept of transcendence. This is the idea of humanity reaching a point where the biological form is no longer required. Some versions of this envision our biological bodies one day evolving into a purely energetic form. More realistic is that one day we discover a way to transfer our consciousnesses into computer minds free to roam the universe. A journey of 100,000 light-years across the Milky Way would be impossible for a living human, but to a non-biological human, it would be survivable. And more than that, the non-biological human could adjust its own experience of time such that a million-year trek might seem to occur in just a few minutes.
All that is certain is the future holds great wonders and possibilities for us and our descendants.
The evolution has just begun…
Reprinted with permission from the author.
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