There is something about walking on two legs that we tend to ignore.
Human infants must learn to be bipedal animals.
We simply are not born with a body / brain system that is capable of standing upright, let alone, walking. We must, through trial and error, and much practice, literally grow into our obligate bipedal locomotion, and it’s a learning process for both body and brain; the human brain must learn to operate the human body.
In fact, each human must repeat the process of becoming bipedal, and all that goes with that peculiar type of locomotion, and it takes years, and many of us are never truly coordinated physical specimens. Athletes, are after all, are elevated in social and cultural stature because they are rare specimens of Master Obligate Bipeds. Although they may be born with physical “potential” top athletes require years of learning: body and brain training, skill practice, and the incorporation of that “body of learning” into both “automatic” and conscious control by the brain.
Which brings up another question. Are human babies born at an extremely premature stage of development in order to accommodate bipedalism? It takes years of practice and external aid by parents and others to become a functional obligatory biped. Quadruped animals often stand, walk and run within minutes of birth; birds are also bipeds, and quite helpless when born. A period of development must take place before they can attempt flying, and even then, it may takes months to years of brain-body feedback to accomplish adult skill.
We assume that the extreme prematurity of human birth is to “allow” for the growth of a humongous brain, but this is not proven. It is, actually, counter-intuitive. The evolutionary changes that occurred due to becoming bipedal may have eventually led to a big brain; but evidence refutes a “destiny” of the highly glorified “big smart brain”. Bipedalism predates “big brains” by millions of years, but there are possibilities as to how bipedalism may have contributed to larger brains.
Early bipeds are “assumed” to have been “like modern bipeds” in functionality – this is a “guess” based on “footprints” that look modern, and on comparative anatomy, computer models, etc. But – it is the brain that “creates – makes possible” those footprints, and tools, and food gathering, and the ability to acquire shelter and protection from predators. The body survives because the brain operates the body; the brain develops while learning to master a complex body.
It’s as if the brain learns to “drive a car” while at the same time, helping to design the car. If the car must navigate and negotiate a simple environment, the brain will “settle in” at a level of energy consumption that balances the expenditure of energy required to fuel behavior of a “complexity” that is “good enough” for survival of the organism. A “small brain” may be entirely sufficient to the operation of such a basic vehicle. Millions of years may pass without the need for an “upgrade” to 4WD, a lighter more maneuverable frame and steering system, and increased speed. A change in the environment may “push for / select” upgrades that require a “better” adapted body, and with it a more complex control center (the brain) –
Through time, small adaptations may suffice, until gradually a threshold is reached; a point where small “improvements” in body function (example – the option of “power steering” on a vehicle) makes a big difference. In bipeds, using the hands, arms and upper body for resource collection and tool manufacture, and/or the capacity to migrate to environments that provide more abundant and better quality food, and the “thinking activities” that accompany these changes, bring about the “tipping point” at which the brain, by learning to operate a few improvements, earns a larger share of the additional calories gained by new behaviors for its own growth and complex development. (The rack and pinion unit went blew out on my truck recently: without power-assist it was almost impossible to drive it to the repair shop – by analogy, it would have been impossible for small bipeds to hunt large mammals before becoming larger, stronger and more agile; before developing the capacity to manipulate and throw objects (rocks) and weapons – but, by engaging in learning new behaviors, those behaviors shaped physical changes. Physical adaptation is a BIG DEAL in the transition from being a prey animal to becoming a predator. The brain would have had to “keep up” with new software, memory capacity, and operating system upgrades – the brain changed.
The switch from being a “prey species” to being a predator (as well as remaining prey for large carnivores) was critical. Being “social” animals, as “we” define social – (neurotypical, neotenic, post-agricultural, fossil-fuel technology-dependent contemporary humans) was a response (and not entirely positive) to entirely different and very recent demands on Homo sapiens. Early “homo” erectus, Denisovan, Neanderthal and related “types” or species, would have succeeded due to advantages that were the consequence of a long history of bipedal / brain-body interactions within a broad range of earth environments that they exploited by migration (Getting the Hell out of Dodge in adverse circumstances may be our most effective form of adaptation).
Importantly, brains require a lot of energy: no brain can be supported by calories that don’t exist; a brain must return a “profit” in energy by exploiting resources and opportunities in the environment. A brain that uses more energy than it can “return” in improved functionality of the body (turn an energy profit) will kill the organism. So, bipedalism is not “just” a method of locomotion; it involves the entire system, especially the “control center brain” and its capacity to “make sense of and respond to” the environment AND to the extraordinary demands of bipedalism itself, including the expansion of behaviors that this ‘new” system makes possible.
This leaves us with a new predicament: Whereas bipedalism appears to have contributed to much of ape-hominid development that we can see in ourselves today, it really is not a “resource for coping with” the biggest environmental challenge that human evolution has faced: the “social crisis” that was precipitated by Agriculture and Urbanization. Masses of humans have been crowded together in unhealthy environments for which our evolutionary history has no pre-adaptations: technology has provided “stop gap” reprieves in this incredibly sudden demand on the human brain and body. These have failed; Homo sapiens is not “naturally social” but survives on severe and draconian accommodations imposed by social and cultural structures, and NOT ON evolutionary adaptation. It took millions of years for the advent of bipedalism to play out as a feedback system between the organism and changes in human environments. Homo sapiens today is failing to adapt as a physical species; we simply cannot “evolve instantly” into a successful social species. Desperate measures prove to be temporary. Our “modern infantile attitude” in the face of “reality” is dominated by hysteria, destruction and magical thinking. “Wonder drugs and wonder gadgets” have been added to “counting on” miraculous intervention by supernatural beings. And now, the race is on to eliminate “physical humans” altogether. It might be the inevitable outcome: self-eradication via technology.