Thursday, October 18, 2007

Causation and Correlation

I was listening to the radio while driving in to work this morning, and in the news part of the morning program, the news announcer was reporting some studies (no exact citation, of course) where some researcher concluded that males having sexual competition and having multiple partners do not have healthy lives. They studied various species that found that in species where the males are monogamous, the males live longer than in species where the males have multiple partners.

Now, if you were given such a report, what's the first thing that comes to your mind, or what conclusion can you draw from it? My constant pessimism about the scientific knowledge of the general public, and how they draw their conclusion would lead me to believe that the average Joe or Joanne would immediately say "Ah ha! This is evidence that not only is monogamy morally right, it is also healthier biologically", or something to that effect.

Now, this is where, if you have been trained as a scientist, a number of questions pop into your head, the way I did when I heard this report just now.

(i) Aren't they comparing apples and oranges when they're looking at different species? Just because the males in one specie happens to live longer than the males in another specie that just also happens to have multiple partners does not mean that having multiple partners is the cause! What would makes more sense is if one compares males within the SAME specie, and then look at the ones with one partner versus those with multiple partners. This way, one removes another possible variation or factors that can influence the outcome.

(ii) This could be the chicken or the egg question. Maybe the reason the males in that specie has multiple partners is BECAUSE they have a short life span! In the need to pass on their genes, they have to find as many females to mate with before they die. So having multiple partners is the consequence of a short life span, not the other way around.

These are the two issues that immediately popped up into my head when I heard the report. Now, without actually reading the research paper itself, I can't make any definitive criticism of it. But that isn't my point here. The point that I'm trying to make is to consider what someone else who do not have a rigorous training and background in science would think given as much information as I got from that radio news report. I would not be surprised if some self-righteous religious fanatic would use something like this to justify this-and-that. One has already seen how Thermo's 2nd Law has been bastardized many times to be used against Evolution.

This is one example where science education is necessary. It isn't just important for the knowledge. It is also extremely important for presenting a systematic and analytical evaluation of "data" that we are bombarded with every day. Politicians and news media often spew statements and claims that either have very little justification or evidence to support them, or the evidence and justification used are either weak, invalid, or non-existent. One could use this research report as justification for monogamy, but one would be using rather dubious conclusion without properly examining the cause-and-effect.

This, more than anything else, is the most important reason why everyone should have at least some knowledge in science and the scientific method.


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