ROANOKE TIMES

                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: THURSDAY, November 24, 1994                   TAG: 9412070006
SECTION: EXTRA                    PAGE: 8   EDITION: HOLIDAY 
SOURCE: JOEL ACHENBACH
DATELINE:                                 LENGTH: Long


WARM-BLOODED ANIMALS STOP GROWING AT MATURITY

Q: Why do trees and fish keep getting bigger and bigger as they get older, but not humans or dogs?

A: You can tell how old a tree is by counting rings. Every year it grows. Same with fish. The older they are, the more you must spread your arms to describe the one that got away.

But humans grow to a certain point and hit a wall, their size reaching a maximum potential, except in the case of Marlon Brando, the great thespian/cetacean.

There is a pattern here, a rather unusual one. Humans, dogs, cats, ants, spiders, honeybees, birds - they all stop growing at maturity. Not so with plants, fish, crocodiles, snakes, all of which keep growing after maturity, albeit far more slowly. What is the distinguishing characteristic between the two groups?

Observation: The living things that keep growing don't have to support their weight.

A tree doesn't feel heavy. It sits on the ground. There's no cost associated with getting taller or stouter (though limbs will fall off if they get too weighted down). A fish is supported by the water around it - it has the same sort of weightlessness we feel when swimming. Snakes slither; they can't stand up, so there's not much cost in getting bigger. Crocodiles mostly just lie around on their bellies, the sneaky devils.

``They don't prance around the way mammals do, or birds,'' says Nick Hotton, a Smithsonian Institution vertebrate paleontologist.

The key factor is warm-bloodedness. Warm-blooded creatures are active, and they need huge amounts of food to keep going. Even on a mellow day it takes lots of energy to be warm-blooded, because you need to keep the internal metabolic fires stoked all the time, as opposed to your average snake, which, being cold-blooded, can literally get cold without dying.

And so if you're warm-blooded you don't want to keep getting bigger and bigger. You want to reach a perfect size and hold it right there.

Now if only the bathroom scale would cooperate.

\ Q: Why did the Renaissance happen?

A: Europe got in one of the greatest ruts of all time, what we call the Dark Ages. Then, wham, Michelangelo's on his back, painting the ceiling of the Sistine Chapel. Explanation, anyone?

First we have an obligation to acknowledge that the Renaissance wasn't an event, per se. It was not a singular thing that happened. It was rather a gradual process in many places in Europe over a period of several centuries - an artistic, stylistic, intellectual evolution driven by political changes, religious schisms, voyages of discovery, etc.

Now that we have that paragraph out of the way we can give you the answer we prefer:

Aristotle.

He and his ilk - the ancient philosophers and poets and artists - were rediscovered in medieval Europe. The Renaissance was a surge of art and literature in the spirit of the ancients. Aristotle was unknown in Europe from about 500 to 1100 A.D. Arabic and Syrian scholars preserved his texts. When he re-emerged he was hailed as The Philosopher, and was the most important intellectual figure of medieval Europe.

There was no single trigger of the Renaissance, but a few events and individuals were particularly important. In the mid-1300s, the Italian poet Petrarch found a number of classical works, including a collection of letters on Roman political life written by Cicero. Petrarch and his buddies became ``humanists,'' interested in human history rather than just theology - they didn't care how many angels could dance on the head of a pin, they wanted to know if Cicero could limbo.

The humanists scoured monasteries for statues, coins, texts, anything they could dig up. Someone eventually found a copy of Aristotle's ``Poetics'' that had been preserved by Islamic scholars.

Robert Hollander, a professor of comparative literature at Princeton, notes that one of the early finds was in the year 1280, when a group of scholars found numerous classical texts in the monastery at Pomposa, near Venice.

``When they found the holdings of the monastery at Pomposa, that's when the Renaissance began,'' Hollander ventures.

Of course, no one knew they were renaissancing. They just thought they had found some neat books. The word ``Renaissance'' was not used until the publication of Giorgio Vasari's book ``Life of the Painters'' in 1550.

Really big news always travels slowly.

\ The Mailbag:

Sandi F., of Rockville, Md., writes that when she travels around the country ``I pass nothing but grass and trees for miles and miles at a time. Why do people say we are running out of space when there is so much of it?''

Dear Sandi: The only space anyone is running out of is closet space. The continental land masses remain quite roomy. The real problem is resources. People consume, shamelessly. We are putting pressure on our supplies of water, food, fossil fuels, ores, topsoil; we're poisoning the environment with toxic waste; we're driving countless species to extinction; we're ruining much of the aesthetic beauty of the planet.

So the problem is not space, it's ``carrying capacity.'' Think of it this way, Sandi: It doesn't matter how much trunk space you have in your car if you got no gas in the tank.

- Washington Post Writers Group



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