Monday, January 29, 2018

Use Your Imagination!

One of a researcher’s best tools is the imagination. What do you think could happen? What could be the explanation? What are the possibilities? Imagination is a fundamental tool on which a researcher’s practice depends.

Recently, I read the book Born to Run (Christopher McDougall), about long-distance running.
It mentioned that women finish ultramarathons at a much higher rate than men and briefly speculated on this, but provided no answer.
Yesterday, I was out for my own run, and the question popped into my head with a possible answer. And at that moment, the idea of writing about the importance of imagination occurred to me. My train of thought went something like: I wonder if heat management explains the superior finishing rate; I wonder how I would research that; What other potential causes would I have to take into account; This is what research is, and I could talk about it in my blog. I was just speculating—I’m never going to do any serious study of why women finish ultramarathons at a higher rate than men. But speculation is fun—imagining possibilities—is hardly different than playing imaginary games as a child, and no more wearisome, if I’m not going to make any effort to turn speculation into real research. But real research starts with some form of speculation—some story about how the world works.
Speculation sparks research. Suppose, I were interested in researching this question of why women finish ultramarathons more frequently than their male counterparts, where would I start?
I would start by trying to imagine why women outperform men in this way.
Is there some psychological dimension, e.g., that men are more aggressive, take more chances, and therefore end up injured more often?
Is there some physiological dimension, e.g., that women are physiologically better suited to the task?
Or perhaps there is some external issue, e.g., sexist race supervisors are trying to sabotage men?
I can imagine the fantastic: maybe Artemis and Hermes had a couple of races, and Hermes won the sprint and Artemis won the marathon, and they have given similar powers to runners of their respective genders. Maybe it’s a side effect of the nefarious plot by K.A.O.S. to spike international water supplies with a mind control drug. Imagining the fantastic is not going to suggest many useful research projects, but it might help suggest something a little less fantastic that would be plausible and interesting.  

To some extent the exercise of imagination is inevitable: a researcher who said “I have no idea, so I’m just going to gather all the data I can,” would still make plans to gather a variety of data, and each plan would reveal an implicit imaginative leap that the data to be gathered were relevant. Taking biological samples would reveal an implicit assumption about a physiological dimension. A researcher gathering biological data might say “I have no idea what causes it, that’s why I’m gathering this data,” but that claim of having no idea does not take credit for thinking that there is a possibility that physiological issues matter. A researcher who was certain that the issue was not physiological, would not gather such data.

If you think there’s a possibility, try to make it explicit: what is the possibility? Is it something in the blood? in hormones? in bone structure? If you’re going to gather physiological data, what are reasons that it might matter?

In the specific case of my idea about women finishing ultramarathons more frequently, I was wondering about heat radiation and long-term performance. Another idea that Born to Run explores is the idea that humans (homo sapiens) evolved as persistence hunters—as hunters who would chase their prey until the animal died of heat exhaustion. Born to Run speaks of running for hours in temperatures of 100+ (F) as a means of bringing in prey.
What I wondered was whether heat radiation and control over internal heat is a factor in the difference in performance between men and women, and how much that specific gender difference is actually dependent on size.
Here’s why size might matter: heat radiation depends on skin area—our skin is our radiator, with the ability to sweat providing additional cooling (one that almost all mammals lack, thus causing their problems with heat exhaustion that makes it possible to run an animal to death over hours). Meanwhile, heat generation depends on metabolic function, and especially on muscular activity.
Imagine that there is a size where the body’s heat generation and heat radiation are balanced (for a given set of conditions). For abstract purposes, let’s say that size is 1 (the unit). For that size, heat generation = heat radiation and the body can perform without problem.  
What happens with a bigger body with similar proportions?  What if size increases by 20%? Now the basic measure is 1.2. Does this affect the balance between heat generation and heat radiation? Yes. Skin area is proportional to the square of the basic dimension, so skin area—the radiator—has increased to 1.44 (1.22). Meanwhile, muscle mass is proportional to the cube of the basic dimension, so the muscle mass—the heat generator—has increased to 1.728 (1.23). Now heat generation (1.73) is greater than heat radiation (1.44). 
The math assumes that an increase in one dimension is matched in the other two, and that may not be the case, but compare a 60” ultramarathoner with a 72” ultramarathoner: what would their weights be? The short one maybe 100lbs.? The tall one maybe 150lbs.? That weight is a reflection of muscle mass—so volume increased by 50% with a 20% increase in height. I don’t have a good estimate of how skin area increased for these hypothetical runners, but assuming that it roughly increased according to the square, to 1.44, or 44% increase, still the increase in heat generation has slightly outstripped the increase in radiation.
All that is just a detailed description of the thinking that supported my speculation (my actual reasoning didn’t include the actual math, just the basic geometric principle that increasing size of a solid object with fixed proportions leads to an increase in the ratio of volume to surface area).  

That is rather far afield from my main thesis, and this post is already long, so I'm not going to make much effort to wind back t my main theme of imagination. But in addition, I'd like to point out the thought processes that were spawned as I tried to explore my speculative idea (my hypothesis) in writing: one one hand, my speculation about a single cause (heat radiation) was placed into a framework of other possible causes, showing a variety of other possible causes that could be the case. On the other hand, my attempt to explain my idea, which led to a closer analysis, including the attempt to put rough numbers to my speculation to assess whether my speculation is consistent with closer inspection. 

In any event, exercise your imagination.

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