Also in this week's column: Are there secrets to life-long brain power? Do we really need a daily shower or bath to stay healthy? Does the size of an animal determine the size of its sperm? How old is my body if the cells keep renewing themselves? Asked by Jo Hopkins of Belmont, California, USA About a century ago, …
The visual cortex is at the front?
They've changed that in the past ten years or so, then. I was always taught that the optic nerve ran to theback of the brain for processing...
OK, so explain tattoos...
The subject says it all, really.
If most of you is under 20 years old, how come there are wrinkly war vets still bearing tattoos?
Gotcha there, huh? :)
Don't fall for the reductionist argument that says your body is the same thing as its cells. That way you can argue that since your cells consist of chemicals, and they of atoms which have been around for millions of years, you are virtually immortal.
But your body - that whole bundle of tricks - as a coherent entity is about as old as you are. Maybe a tad older.
Tattoos are created by injecting ink under the skin, which is how they persist even though we shed our skin almost continuously. If you get a high level tattoo (or semi-temporary) (under 2 layers of skin, for example) that tattoo will normally last a few weeks-months before it fades away with the layers of dead skin being shed by our body.
Watch it on the atomic scale.
You change about 10000000000000000000 times per sec.
To be alive is to change. A self is not a thing, it is a process. Every moment, I become a slightly different person to the person I was a moment before.
Q: How old is a river, if water keeps flowing through it?
A: A river is not a substance: it is a configuration of substances and processes. A river is the same river as long as water keeps flowing through it. New rivers may form after earthquakes and volcanic eruptions; rivers die when their water dries up. But ultimately, a river is defined conceptually: is "river" the same as "estuary"?
Your body is a similar configuration. Substances flow through it, lingering a while, then leaving. The configuration remains much the same: that is your body. Ultimately, too, your body is defined conceptually, but you'll have to sit down and think about that one.
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