Language as an Interface 〔Revised on 20250302〕

  Today, the diverse non-human species found across the Earth have undergone screening by natural selection pressures, evolving into species with highly fit bodies (phenotypes) that constitute the biosphere.

Humans, instead of evolving their bodies in response to selection pressures, have adapted and survived by evolving (modifying) their tools.

And tools, in essence, are language.

As individuals, humans are quite fragile. If left naked outdoors in winter, they would die in about three hours. The clothing that protects the human body and the houses that shelter it are results of humans communicating with each other and working together as functional groups. While communication and interaction include nonverbal elements, these require the condition of sharing the same place and time. However, when communicating across different places and times, humans inevitably rely on language as a medium. To receive messages from Confucius or Plato spanning over two thousand years, we have no choice but to rely on wooden tablets, inscriptions, or papyrus documents engraved with words rather than video letters.

The existence of the human brain and the development of language are likely inseparable. This seemingly unbalanced bodily structure signifies that humans halted bodily evolution and instead evolved language as a tool.

Animals interface with the external world through their bodies. This does not refer solely to their exposed skin but to their entire body, including internal organs, which serves as their interface with the environment. All living beings, whether animals or plants, are continuously subjected to natural selection pressures through their material existence. For example, climate changes such as warming or cooling over hundreds or thousands of years represent changes in selection pressures for organisms. Even if the environment remains unchanged, mutations or genetic recombination within species alone can create phenotypic variations that result in significant differences in fitness.

The evolution of species can be understood as the contingent outcome of the autonomous changes in the "keyhole" of the environment and the autonomous changes in the "key" of phenotypes. In such cases, over multiple generations, species that exhibit a fitness performance of at least 1 in asexual reproduction or at least 2 in sexual reproduction will survive. If this process is preserved in fossils and later discovered by humans, we refer to this historical replacement as "evolution." The essence of biological "evolution" can be described as contingent replacement. Consequently, due to this contingency, even events of explosive evolution beyond human imagination, such as the Cambrian Explosion, can occur.

The phenotypes (bodies or outer shells) of biological species, including animals, serve as interfaces through which they engage with the "thing-in-itself" (Ding an sich, Kant). The traces of such evolutionary changes remain on Earth today. However, at some point in history, humans inserted language between the material body and the environment. From that moment on, humans could no longer directly touch the "thing-in-itself." Once they put on the mask of language—this interface—they became unable to remove it.

All living beings on Earth construct their own Umwelt (lifeworld), as described by Jakob von Uexküll. In the Umwelt of animals, their bodies function as interfaces. Therefore, when the environment undergoes rapid or gradual changes, or when genetic mutations occur within a species, the previously stable fitness of that species changes, altering the biosphere.

In contrast, the human Umwelt includes language as an interface, granting it overwhelming plasticity compared to species that rely on their bodies as interfaces. This is why, despite being the only extant species of its kind on Earth, humans have adapted to various regions through an astonishing diversity of lifestyles, like a kaleidoscope.

By acquiring language, humans have gained an immense freedom as a species. However, this freedom comes at the cost of being unable to access the environment as the "thing-in-itself" (Ding an sich). Humans have been exiled from "nature" into "history," and they are destined to endlessly create new "histories," wandering between the long toil of this endeavor and fleeting moments of joy.

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※Notes
This article is a translation of the following Japanese article by DeepL.
インターフェースとしての言葉（ Language as an interface ): 本に溺れたい 2016.11.03