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Tuesday, September 2, 2008

Bilateral Symmetry

I suspect the reason we love bilateral symmetry is because we are made that way ourselves, as is most of the animal kingdom. In a larger sense, we love patterns, repetitions of sounds or shapes or colors, perhaps because we always hope that in the apparent chaos of reality is an underlying order, a unifying principle, a reason for the unfolding of the universe and for ourselves. Whatever the reason, bilateral symmetry is pleasing to the eye. The example above is the British Columbia Legislative Assembly Building from behind, rather than the more usual view from the front. And here's an interesting article on bilateral symmetry.


Eki said...

Thank you for the explanation and the link. That explains what I've felt all along. The photo is an excellent example of what you explain.

I have similar post (not building, but part of it) and how we incline to finding order in the chaotic realities of an urban life.

Thanks again.

Janet Kincaid said...

Interesting information on bilateral symmetry. I guess as creatures of relative habit, we find some measure of comfort in the orderliness of symmetry. Federalist architecture seems to be appealing for similar reasons.

Great photo for illustrating this concept!

USelaine said...

Another result of our instinctive connection to the faces of living things is that we sometime conjure faces in anything symmetrical that lends itself. Like this building...

Sharon said...

I loved your information on bilateral symmetry. Sometimes I think I'm even more enamored by patterns than most people. This picture is great. I'm wishing I had gone behind this building when I was there.

John Sandel said...

The article you link to says, in part "bilateral symmetry must have evolved for a reason," which misapprehends a fundamental dynamic of nature and, hence, of natural selection: nothing evolves for a reason.

The most bizarre thing about natural selection is that it's entirely dumb and blind: this is the "good news" of science—the miracle hidden in nature's use of the universe's bottomless well of time. The drivers of evolution are genetic rules, encoded in chemical molecules, which collide with sheer circumstance, as those molecules' bearers (living things) survive the world's vagaries.

The overwhelmingly common result of these innumerable collisions is injury, disease and death. But sometimes the molecules have chanced into a combination that confers some advantage on the individual bearer. In the vast majority of cases, that advantage is only enough to do no harm. Thus do species trundle through longeurs of little evolutionary change—millions of years can pass without significant change.

In the tiniest minority of the latter cases, the advantage is enough to give the bearer a leg up on its competitors, and it passed on through reproduction. It's these vanishingly-few success stories which we perceive as the entire biota of earth, so it's natural for us to see a "reason" behind the process. A better word might be "opportunity."

There is no intent in evolution—there is no design. It's all chance, all collisions. Bilateral symmetry in terrestrial fauna, e.g., probably evolved for the simplest of reasons: locomotion. An asymmetric body-plan would make land motion, at least, difficult and probably dangerous. Thus the bilateral scheme confers another accidental advantage: more safety from injury. That alone, repeated infinitely for 4.5 billion years, is plenty of opportunity for inheritors of bilateral bodies to survive their asymmetric competitors.

Who knows how many millions of species, down through the forgotten paths of time and suffering, have "tried" other body plans? The fossil record suggests that fauna settled into bilateralism rather early on; that could be a holdover from our aqueous origins, where asymmetry is less of a disadvantage, but bilateralism aids fast motion (escape from predators).

The thing to remember is all those countless chance collisions between our genetic code and sheer circumstance: what a drama! If natural selection is distasteful as an Origin tale (putting, as it does, our blinkered primate self-centeredness in its place), or if the implications for our future are too foggy to perceive, we might do well simply to accept the evidence and get on with improving our lot. As Kurt Vonnegut says: because so much of life seems to consist of banging up against one another, we might as well become "fans of collisions."

USelaine said...

Kurt Vonnegut also said, "We are here to help each other get through this thing, whatever it is." Words to live by.

John Sandel said...

If I recall correctly, he was referring to a meatloaf.

Benjamin Madison said...

Thanks all for your kind and thoughtful comments.

d.c.: I was going to remark in my post that government (federalist) buildings tend to be particularly symmetrical because we expect our legislation to make that kind of black/white right/wrong distinction clearly. Our government buildings reflect our longing for order and predictability in social affairs.

Bernie, it's my personal opinion that the "Theory of Everything," if/when it finally arrives will subsume both intelligent design and mechanistic probability theories. Until then, an open mind seems best (for me).

Elaine - I don't know if helping each other get through this thing qualifies as a reason for existence but it does seem a good way to relate to the universe in general.

John Sandel said...

Re: TOEs—yeah, there's a strong argument to be made against mechanistic models of nature. Yet the evidence (here, natural forms, esp. as encased in stone) is not of our making.

The furthest I'm prepared to go, metaphysicallly, is too say I'm convinced that truth (which is the value of evidence) is not a human value. We're in the universe but don't create it. We approach truth at the peril of our beliefs. Given a choice between truth and belief, I choose the former, which has caused me pain.

Our species is in pain; we're suffering a long waking from belief—belief like a child's dream—and when we open our eyes, as a species, what we see is mainly the roofless vault of stars. We came from them; we'll return to them. Meantime, we're obliged to be as rigorous as we can when confronted by the evidence of nature's ignorance of us. This little heated rock is our best copybook for practicing maturity.

Along the way (as Vonnegut also said), "god damn it, you've got to be kind." The rest is silence.

Anonymous said...

From Wittgenstein's Tractatus Logico-Philosophicus: "About that which we can say nothing, we are obliged to stay silent."