Saturday, 4 February 2012

All Things Being Inequal

I'm sat here watching Hugh's Three Hungry Boys, which is a slightly disappointing incarnation of a "get from A to B without any money" challenge where, at least in my expectation, there should be a lot more foraging and a lot less scavenging and working in exchange food. However, working for your food itself brought to mind an important concept in survival; that of the inequality.

In mathematics, an inequality describes the relationship between two quantities, stating that one is either less then or greater than the other. So simple is this concept, that we use it every day. If the temperature is less than is comfortable, we turn the heating up. If the amount of money in your pocket is less than the bus fare, tough luck. These are luxuries we might not have in a genuine survival situation, but there is one day to day inequality from the human biology which is extremely important in survival:
calories taken in compared to calories expended
If calories in is greater than calories out, then we put on weight, if less, then we lose weight. From a dieting perspective, the latter makes sense meaning we either eat less to reduce calories in or work harder, increasing calories out. Either way, we're trying to tip the inequality the other way, thus losing weight. In addition, the greater the difference between these two quantities, the greater the rate of weight loss or gain.

In survival situation, it would be unusual for us to find ourself concerned with weight gain, more likely weight loss and more concerningly, rate of weight loss. Loss can be mitigated by reducing calorie expenditure by doing less work, keeping warm and generally sleeping as well as eating more, but here in lies another inequality dressed in a question.
At what cost is in calories is my food coming?
That is to say, are the calories I gain from the food I eat greater than the calories expended getting it? If it costs you more in calories to get the food than you gain from it, then that's a net loss, which is a bad thing. I remember Bear Grylls climbing a huge tree to get a single egg, which is not only a massive risk of injury, but a net loss in calories, which didn't help his cause. An example from the show is that the three chaps did fifteen hours of weeding in exchange for five pounds of vegetable. Was it worth it? Let's see.

Weeding costs about 300 to 350 calories an hour, depending on how much you weigh and how hard you work. The chaps worked pretty hard, so they probably expended about 5000 calories each over the 15 hour period.

I seem to remember the box containing, leeks, turnips, chard, spinach, potatoes and beetroot amongst other, so an average of, say, 50 calories per 100g. That's about 1200 calories in total which doesn't seem to offset the work. The boys were in luck, however, as they were subsequently given a kilo of honeycomb. Whilst standard, jarred honey is around 30 calories per 100g, honeycomb is more like 400. So that's 4000 calories for the kilo. Giving us a total of 5200. Hurrah, we might think, until we realise they had to share it between the three of them, making about 1400 calories each. Damn! Back to a loss.

But, you might argue, they would have used a certain amount of calories anyway. This is true. Each of the  chaps would have burned around 80 calories per hour just sitting around. So, assuming that's not been taken off of the weeding rate already, that's about 1200 calories. How are we doing so far?
calories in = 1400
extra calories out  = 5000 - 1200 = 3800 
so far
calories in are less than extra calories out
For those who saw the show, you might remember that they said one of the advantages of weeding is that you can collect wild food on the way. The really observant amongst you will have noticed one of them with a stalk of chickweed. They also had some stable in the van. So, if we want to flip the equation around, we'd need another 2400 calories in wild food, rice and spuds, which about the amount that an average male needs per day.

In summary, even with the honey and some wild food, they would have been better off, calorie-wise, just sitting on their arses.

This might seem like a contrived, TV example, as is the case with the egg up the tree, but it illustrates an important point about calorie expenditure in a survival situation. It's important to ensure that we waste as little of our calories as possible, by making sure we're always on the look out for foragable food whilst, for instance, combining gathering food with getting water and checking traps. We might consider placing our camp nearer to such daily resources as water, wood and food, in order that we expend less calories walking, which takes up about three times as much as sitting.

In cold weather, we should ensure we make small, efficient fires we can sit close to and reflect the heat in, rather than huge fires we have to constantly go searching for wood for. There's another inequality there. Are the calories I'm wasting keeping myself warm internally greater or less than those I'd expend gathering wood for a fire? If you're walking around all day getting wood for a fire you're not sat next to, you're collecting wood for nothing and wasting even more calories.

This same concept can be applied to water in a low water environment. We use water all the time, but sometimes more than others. Rather than sweat a litre of water in the mid day sun collecting from a small drying stream, it would be better to wait until it's cooler. Is it worth using the water you have to cook rice, or is it better to just drink it, staving off dehydration rather than hunger? Another inequality:
if water in is less than water used then you will dehydrate
The greater the difference, the faster you'll dehydrate and the quicker you'll die.

There's no need for a calculator and calorie counter in a genuine survival situation, just use your head. Limit and combine activities, work efficiently and think. Consciously applying this simple concept of comparing benefit an loss to your actions might save your life.

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