Talmudic Question #96

Bacterial cells are smaller than eukaryotic cells, with some exception. Viruses are smaller than bacteria, with some exception. These are just two examples of why definitions in Biology, unlike in Physics and Chemistry, most often need to be qualified. What does this tell us about Biology?

Comments

[KRS]

Big fleas have little fleas,
Upon their backs to bite 'em,
And little fleas have lesser fleas,
and so, ad infinitum.

Anyone want to bet on when quarks will be smashed into smaller constituent particles?

[julian davies]

I suggest that you should ask "what does this tell us about microbiologists and physicists?"

[barry]

organisms rewrite the definitions and rules while they are playing by them.

[me]

Just that Biology is exceptional, of course! :>)

[Ben Murray]

Biology is, in many respects, a historical science (at least where evolution is involved). The contingent details of what actually happened matter, often a lot.

I think you could make similar statements about other sciences with substantial historical components, such as geology or human history itself.

Elio replies:
You make an interesting point. You may even be right! Thanks.

[Dredd]

Dollo's law may not be.

Elio replies:
Ha! In the Wikipedia entry for Dollo's Law (of ireversiblity in evolution) there is a section devoted to "Proposed exceptions"

[Indrani Roy]

Biology is a young science.Biology is as yet an inexact science.

[Mark O. Martin]

Just thinking about this as teaching freshmen. Consider:

"Here are Mendel's Laws. Got 'em?" Students all smile and nod.

Then:

"Good! Here are the exceptions to Mendel's Laws."

[Johan Laserna]

Also (echoing bks), stars are brighter, and bigger, and hotter, than planets, with some exception.

[Mark O. Martin]

I had to chuckle with this TQ, Elio. I well remember my physics professor in college teaching us this maxim: "Often, constants aren't and variables don't."

[Huila]

Either biology is too complicated or we know too little about it.

[Hollis]

We crave patterns and rules, they make accurate prediction easier and survival more likely. So we try to find them everywhere. Biological entities and their histories are too complex for hard and fast rules and it gets worse as we aggregate up. Things like plant communities, ecosystems, etc., can seduce us into seeing patterns that aren't even there! -- from "The Lament of a Field Botanist" ;-)

TQs are so fun. Thanks, Elio.

Elio replies:
Nice words, much appreciated. You make a most appropriate point.

[bks]

As a computer scientist who has worked in all three disciplines my take is that biologists only think that theirs has fewer hard and fast rules. Chemists still struggle to explain the "phenotype" of H2O:
http://www.lsbu.ac.uk/water/anmlies.html

And physicists are immersed in rather immaterial concepts, such as "dark matter"
"big bang" and the logic- and category-defying quantum realm:
Is it a wave or a particle? It's both!

--bks

Elio replies:
I'm glad we heard from someone who is versed in physics and chemistry. Not knowing much of either, I'm on shaky grounds, but I would still argue that definitions are more universally porous in biology. But I'm eager to hear from others in the know, being that I'm out of my depth.

I was delighted to encounter bks' fascinating blog at http://www.ironic.com. It spans a wide range, from pictures of protists to musings on physics and biology.

[Ami]

1) That size matters.
2) That we the living are not created equal.
3) The smaller you are the more annoying you get.
4) It ain't over till the fat lady sings.