Biology 441, Spring 2013


When scientists report evidence that " X causes Y " their conclusion may be based on different sorts of evidence:


a) Mutation or inactivation of gene " X " results in alteration or prevention of process or structure " Y ".

b) The " X event " always occurs just before the " Y " event.

c) Or adding more of substance X causes Y to form (sooner?).

d) Surgically removing organ X causes Y not to occur (at all?).

e) Moving structure X to an abnormal location causes event Y, or structure Y, or process Y, or chemical reaction Y, to occur at or near the location to which you moved structure X.

f) If we fluorescently label substance X, and inject it into embryos, then it accumulates at the location of Y.

And I am sure that you can now invent at least 1 or 2 more?

When you read "difficult" scientific research papers in Nature and Science Magazine, you need to be prepared for all these, and some other meanings of "X causes Y".

In addition to understanding the specific subjects in a research paper, it would be worth your effort to collect examples of different senses in which people say that "X causes Y".

This can be every bit as much fun as keeping notes on how many different state license plates you see on cars in traffic.

Like: Hey! Is that a Montana license plate over there? Wow!

How cool is that?

Most of them are some variation on X is a sufficient (and usually also necessary) precondition for Y to occur.


Join us, and bring order to the Solar System! .........
We plan to start small, and gradually work our way up to ruling the Galaxy.


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