This post has made it to the Hacker News front page, see the discussion there.
If you like this, you might also like my Instagram channel Nerd on Bars @nerdonbars where I calculate the power output of various athletes and myself.
This is an addendum to my previous post The Kilowatt Human. I mean it as half-entertainment and half-futuristic speculation. I extrapolate the following insight more into the future:
Before the industrial revolution, over 80% of the population were farmers. The average human had to do physical labor to survive. The average human could not help but to “bodybuild”.
Since then, humans have built machines to harness the power of nature and do the physical labor for them. What made the human civilization so powerful robbed individual humans of their own power, quite literally. The average pre-industrial human could generate a higher wattage than the average post-industrial human of today—they had to.
Before the industrial revolution, humanity’s total power output was bottlenecked by human physiology. Humanity has since moved up in the Kardashev scale. Paradoxically, the more power humanity can generate, the less physical exercise the average human can economically afford, and the weaker their body becomes.
Similar to the growth in humanity’s energy consumption, the average human’s physical strength will move down a spectrum, marked by distinct Biomechanical Stages, or BMS for short:
| Biomechanical Stage | Technology Level | Human Physical Labor | Biomechanical Power Condition |
|---|---|---|---|
| BMS-I (Pre-Industrial) | Stone Age to primitive machinery (sticks, stones, metal tools, mills) | Nearly all tasks powered by muscle; farming, hunting, building | High: Strength is universal and necessary |
| BMS-II (Industrial-Modern) | Steam engines to motorized vehicles | Most heavy work done by machines; exercise optional, not required | Moderate to Low: Average strength declines as tasks mechanize |
| BMS-III (Post-Biological) | Brain chips, quantum telepresence, digital existence | Physical labor negligible; teleoperation replaces bodily exertion | Nearly None: Muscles vestigial or irrelevant, having a body is comparatively wasteful and an extreme luxury |
Why do I write this? My father grew up while working as a farmer on the side, then studied engineering. He never did proper strength training in his life. I grew up studying full-time, have been working out on and off, more so in the last couple of years. And I still have a hard time beating him in arm wrestling despite the 40 years of age gap. Our offsprings will be lucky enough if they can afford to have enough time and space to exercise. I hope that their future never becomes as dramatic as I describe below.
Biomechanical Stage I (Pre-Industrial Human Power)
Began with the Stone Age, followed by the era of metal tools, basic mechanical aids like mills, and ended with the industrial revolution:
Stone Age: No metal tools, no machinery. Humans rely on their bodies entirely—hunting, gathering, carrying, and building shelters by hand. Biomechanical power is the cornerstone of survival. The average human can generate and sustain relatively high wattage because everyone is physically active out of necessity. Most humans are hunter-gatherers.
Metal tools and agriculture: Introduction of iron and steel tools improves efficiency in cutting and shaping the environment. Most people farm, carrying heavy loads, tilling fields, harvesting. Though tools reduce some brute force, overall workloads remain high and physically demanding.
Primitive machinery (e.g. mills): Waterwheels and windmills start to handle some repetitive tasks like grinding grain. Still, daily life is labor-intensive for the majority. Physical strength remains a defining human attribute.
In this era, the biomechanical power of the average human is relatively high. The average human can generate and sustain relatively high wattage because everyone is physically active out of necessity.
Biomechanical Stage II (Industrial-Modern Human Power)
We are currently in this stage. It began with the Steam Age, followed by the widespread use of internal combustion engines and motorized vehicles, and will end at the near-future threshold where technology allows a human to be economically competitive and sustain themselves without ever moving their body.
Steam engine and early industry: Factories powered by steam reduce the need for raw human muscle. Some humans shift to repetitive but less physically grueling jobs. Manual labor declines for a portion of the population.
Motorized vehicles and automation (our present): Tractors, trucks, and powered tools handle the heavy lifting. Most humans now work in services or knowledge sectors. The need to exercise for health arises because physical strength no longer follows naturally from daily life. Specialty fields (construction, sports, fitness enthusiasts) maintain higher-than-average output, but they are exceptions.
Humans still have bodies and can choose to train them, but the average sustained power output falls as convenient transport, automation, and energy-dense foods foster sedentary lifestyles.
Robots and AI: Robots and AI are increasingly able to handle physical tasks that were previously done by humans. This further reduces the need for human physical labor.
As machines handle more tasks, the average person’s baseline physical capability drops. Exercise shifts from natural necessity to a personal choice or hobby.
Biomechanical Stage III (Post-Biological Human Power)
Future scenarios where brain-machine interfaces, telepresence, and total virtualization dominate. Will begin with a Sword-Art Online-like scenario where neural interfaces allows a human to remotely control a robot in an economically competitive way, while spending most of their time immobilized. Will end in a Matrix-like scenario where the average human is born as a brain-in-a-jar.
Brain Chips and Teleoperation: Humans remotely control robots with no physical exertion. Commuting is done digitally. Physical strength becomes even less relevant. The population’s average biomechanical output plummets because few move their own bodies meaningfully.
Quantum Entanglement and Zero-Latency Control: Even physical constraints of distance vanish. Humans may spend their entire lives in virtual worlds or controlling machines from afar, further reducing any reason to maintain physical strength.
Bodily Sacrifice, Brains in Jars: Eventually, bodies become optional. Nervous systems are maintained artificially, teleoperating robots when needed. Muscle tissue atrophies until it is nonexistent. The concept of human biomechanical power no longer applies. The definition of what a human is becomes more and more abstract. Is it organic nerve tissue or even just carbon-based life?
The human body, if it exists at all, is not maintained for physical tasks. The average person’s muscular capability collapses to negligible levels.
How does the Kardashev Scale align with the Biomechanical Stages?
In my opinion, the stages will not align perfectly with Kardashev Type I, II and III civilizations. Instead, they will overlap in the following way:
| Kardashev Type | Biomechanical Stage | Description |
|---|---|---|
| Type I (Planetary) | BMS-I (Pre-Industrial) | The average human can generate and sustain relatively high wattage because everyone is physically active out of necessity. Most humans are hunter-gatherers or farmers. |
| BMS-II (Industrial-Modern) | Humans still have bodies and can choose to train them, but the average sustained power output falls as convenient transport, automation, and energy-dense foods foster sedentary lifestyles. We are still limited to 1 planet. | |
| Type II (Interstellar) | BMS-III (Post-Biological) | The average person’s muscular capability collapses to negligible levels. The concept of human biomechanical power no longer applies. The definition of what a human is becomes more and more abstract. |
| Type III (Galactic) | What kind of societal organism can consume energy at a galactic scale? Is there any hope that they will look like us? |
I think that by the time we reach other stars, we will also have pretty sophisticated telepresence and brain-machine interface technology. In fact, those technologies might be the only way to survive such journeys, or not have to make them at all, as demonstrated in the Black Mirror episode Beyond the Sea:
Black Mirror: Beyond the Sea. Go watch it if you haven’t, it’s the best episode of the season.
So BMS-III might already be here by the time we are a Type II civilization. As for what an organic body means for a Type III galactic civilization, I can’t even begin to imagine.
This post has mostly been motivated by my sadness that while our life quality has increased with technology, it has also decreased in many other ways. We evolved for hundreds of thousands of years to live mobile lives. But we became such a successful civilization that we might soon not be able to afford movement. We are thus in a transitory period where we started to diverge from our natural way of life, too quickly for evolution to catch up. And when evolution finally does catch up, what will that organism look like? How will it feed itself, clean itself and reproduce? Will the future humans be able to survive going outside at all?
In another vein, technology could also help us perfectly fit bodies by altering our cells at a molecular level. But if there is no need to move to contribute to the economy, why would anyone do such an expensive thing?
My hope is that sexual competition and the need for reproduction will maintain an evolutionary pressure just enough to keep our bodies fit. This assumes that individual humans are still in control of their own reproduction and can select their partners freely. Because a brain-in-a-jar is obviously not an in-dividual—they have been divided into their parts and kept only the one that is economically useful.
