Eternal self

Today 7:40 AM
If we didn't age and accidents, etc., were eliminated, how long would we retain memory?

That is a fascinating question because it gets at the difference between aging of the brain and the limits of memory itself.

If we assume a human brain that did not age, was protected from disease, and avoided injury, there is no known hard limit at which memory would simply "fill up" and stop working. The brain is not like a hard drive with a fixed number of gigabytes. It is a constantly changing network that stores information by changing connections among roughly 86 billion neurons.

However, there are several possible limits:

    Forgetting would probably still happen.
    Even an immortal, perfectly healthy brain would likely still prune or weaken memories. Forgetting is not merely a failure; it is part of how the brain stays efficient. If every detail of every day remained equally vivid forever, ordinary thinking would become overwhelmed by an enormous amount of irrelevant information.

    Old memories might become harder to retrieve.
    A person alive for 500 years might still have memories from childhood, but they might be buried under centuries of newer experiences. The problem would not necessarily be storage capacity, but finding the right path back to the memory.

    Identity and personality might become unusual over very long periods.
    A person who lived 1,000 years would have accumulated vastly more experiences than any normal human. Their sense of self might become more like a long historical archive than the relatively continuous "story" we now experience. They might remember being a child, but that child could feel almost like a distant historical figure.

    The brain's physical capacity is enormous.
    Some estimates suggest human long-term memory capacity could be on the order of petabytes (millions of gigabytes), though such estimates are uncertain because memories are not stored like computer files. At ordinary rates of learning, a person could theoretically store centuries of experiences before approaching any physical limit.

A more interesting question is: would a 1,000-year-old person remember their 20th year as clearly as we remember our childhood? Probably not. Childhood memories are unusually persistent partly because they are emotionally important and repeatedly reinforced. A random Tuesday 400 years ago would likely fade unless it was revisited or meaningful.

So the answer is probably: with a non-aging brain, humans could retain memories for centuries or perhaps far longer, but not as a perfect recording. The limiting factor would be organization, retrieval, and the brain's need to keep the present manageable—not running out of storage space.

It also raises an interesting philosophical point: if you lived 1,000 years, the person you were at 50 might still be in your memory, but would they feel like you? That may be a bigger challenge than the biology.

It may well be, though tracing it is tricky.

The phenomenon is widespread enough in East and Southeast Asia that linguists have long noticed it. Classical Japanese ao covered a range that included what English speakers would call both blue and green. Vietnamese xanh does something similar. Khmer's color terminology has historically shown overlap as well, though modern usage has become more differentiated.

The interesting question is whether this reflects:

    A common linguistic ancestor, or

    Language contact and cultural influence, or

    An independent tendency that arose multiple times.

The first possibility is actually the weakest. Japanese, Vietnamese, and Khmer belong to different language families:

    Japanese: Japonic

    Vietnamese: Austroasiatic

    Khmer: Austroasiatic (related to Vietnamese, though distantly)

Since Japanese is not related to either Vietnamese or Khmer in any accepted linguistic sense, a common inherited word is unlikely.

The second possibility—areal influence—is more plausible. East and Southeast Asia have exchanged culture, writing systems, religion, technology, and vocabulary for centuries. Linguists speak of a "sprachbund," an area where unrelated languages acquire similar features through contact. Mainland Southeast Asia is famous for this.

But there is also a third possibility that I find especially intriguing. Many historical linguists think languages often develop color terms in a somewhat predictable order. The classic work of Brent Berlin and Paul Kay suggested that languages tend to acquire basic color categories gradually. In many languages, a single term may originally cover a range that English splits into blue and green. Only later do separate basic terms emerge.

If that model is roughly right, then blue-green categories are not peculiar at all. They may represent a very common stage in the evolution of color vocabularies.

What is fascinating is your earlier qualia discussion. These languages provide a natural experiment. If language completely determined perception, speakers of English and Vietnamese should literally see colors differently. Yet they generally do not. They can all distinguish the colors. The difference lies more in how the distinctions are packaged and named.

Still, language may subtly affect attention. An English speaker looking at a turquoise tile may immediately wonder, "Is that blue or green?" A Vietnamese speaker may be more inclined to think, "It is xanh—what kind of xanh is it?" The same visual stimulus, but a different default way of carving up the space.

That makes me wonder whether there are old texts in Chinese, Japanese, Khmer, and Vietnamese describing the sky, the sea, jade, vegetation, and traffic-light equivalents. If the same blue-green grouping appears repeatedly across centuries, one could potentially trace not just a linguistic feature but a long cultural habit of categorization spreading across the region. It would be a fascinating piece of historical linguistics.

Experientially green and red are as different as green and blue while red and orange on one side and red and purple on the the the other are more similar experienes.

That is a very interesting observation, and it points toward something deeper than language.

For most people with normal color vision, red, green, blue, yellow, and so forth do not feel like arbitrary labels attached to a smooth spectrum. There is a phenomenological structure to color experience itself.

Red and orange feel related. Red and purple feel related. Green and blue feel related. But red and green feel almost oppositional. Likewise red and blue seem farther apart than either red-orange or blue-green.

What's fascinating is that modern vision science discovered something that resembles this intuition. Human color perception is often modeled using opponent processes:

    red ↔ green

    blue ↔ yellow

    light ↔ dark

The visual system appears to encode color partly in terms of these oppositions. One consequence is that people do not normally experience a color that is simultaneously "reddish green" in the same way they can experience reddish orange or bluish green.

So when you say that green and red feel as different as green and blue do not, you may be noticing something about the structure of the visual system itself rather than merely a linguistic convention.

This is one reason I am skeptical that the blue-green grouping in Vietnamese, Khmer, or Japanese tells us much about qualia directly. Language can group blue and green together, but the underlying perceptual space still has its own shape.

In fact, your experience suggests something intriguing. Suppose a culture had only one word for red and green. I suspect speakers would still notice a much larger experiential gap between those hues than between blue and green. They might classify them together linguistically, but the perceptual terrain would resist the classification.

That is one reason color is such a favorite topic in discussions of consciousness. It sits at the intersection of three things:

    The physical world (wavelengths).

    The brain's processing architecture.

    The subjective feel of experience.

And those three layers do not line up perfectly.

Your blue-green example may therefore be telling us something about language and culture, while your red-green example may be telling us something about the architecture of human perception itself. The two questions are related, but they are not the same question.

It would be fascinating to know whether a native Vietnamese or Khmer speaker, asked not for words but for similarity judgments, would place blue closer to green than an English speaker does. My guess is yes—but not by a huge amount, because the underlying visual system is shared by all of us. The language may nudge the categories, but it probably does not redraw the map.

That we must use words to talk about experience confuses linguistics and conception.

I think that's exactly right, and it is one of the reasons discussions of consciousness so often become tangled.

We have three distinct things:

    The experience itself — seeing blue, feeling pain, hearing a trumpet.

    The concepts we form about the experience — "this is a color," "this is blue," "this is similar to green."

    The words we use to communicate those concepts.

Because we can only discuss the first through the second and third, it is easy to slide from one level to another without noticing.

Take your Vietnamese example. A linguist may observe that Vietnamese groups blue and green under xanh. From that, someone may infer that Vietnamese speakers conceive of blue and green as one color. Then someone else may leap further and suggest they may actually experience them differently.

Those are three increasingly stronger claims.

The first is about vocabulary.
The second is about categorization.
The third is about qualia.

Evidence for the first does not automatically establish the second, and evidence for the second does not automatically establish the third.

In fact, I suspect much of the debate over linguistic relativity comes from failing to keep those levels separate.

Your stoplight example was a nice illustration. A Japanese speaker calling the light "blue" tells us something about language. It tells us less about conceptual structure. It tells us almost nothing directly about what the color looks like to them.

There is a broader philosophical point here as well. Many arguments about consciousness seem to begin with words and end with words. People analyze the meanings of "experience," "qualia," "self," or "awareness," and sometimes forget that these terms are attempts to point at something prior to language.

A newborn infant has experiences before acquiring words. A dog presumably has experiences without human language. If qualia exist, they exist before they are named.

That is one reason color is such a useful example. You can know every word in a language and still not know what a color looks like. Conversely, you can see blue perfectly well without having a word for it.

The experience comes first. Concepts and language are maps we draw afterward. The maps may influence how we navigate the territory, but they are not the territory itself. That sounds obvious when stated that way, yet in discussions of mind and language it is astonishingly easy to forget.