by Quentin Long
©2009 Quentin Long
One piece of advice I often give to aspiring authors is, Ask the next question. Whether youre creating a character or establishing your setting, youll have decided that certain things are or arent truelike maybe the character has a lifelong fear of clowns, for instance. Whatever decisions youve made, ask the next question means that you shouldnt just take them at face value and leave it at that. Rather, you should ask why such-and-such is true, and/or If thus-and-so is true, what are the consequences?
And yes, you can keep on asking why? and what are the consequences? for as long as you care to. The idea is to become more familiar with whats in your story, so that youre less likely to write stuff which works against the things youve already established. For this editorial, Im going to start with a single fact, work with it for a while, and see how far I can get
Flash fact: If youre counting biomass in a viable ecosystem, it takes about ten pounds of prey to keep one pound of predator going.
This 10:1 ratio applies whether the relevant life-forms are wolves and rabbits, or cows and grass, or whatever and whatever-else. So if a particular area A has X pounds of edible plantlife, it follows that area A can support, at most, (X/10) pounds of herbivore. Less obviously, area A can support a maximum of (X/100) pounds of predators which feed on those herbivores, and (X/1,000) pounds of predators that prey on the herbivore-eaters, and so on.
Why does this matter? Turn it around: If it takes ten pounds of prey to keep one pound of predator going, that means one pound of predator needs ten pounds of prey to stay alive. Thus, one pound of herbivore needs ten pounds of edible plants; and one pound of herbivore-eater needs ten pounds of herbivore, which, in turn, need 100 pounds of edible plants. And lets say you happen to have predators who specialize in feeding on leaf-eaterswhat you might call second-level predators, as opposed to the herbivore-eaters, who might similarly be termed first-level predators. Given that every rung of the who-eats-who ladder involves a 10:1 biomass ratio, it follows that one pound of second-level predator needs ten pounds of first-level predator, which requires 100 pounds of herbivore, which, finally, needs 1,000 pounds of edible plants. And then there are third-level predators
Heres the take-home lesson: Predation is expensive. This is one of the reasons people like to advocate vegetarianism; you cant avoid that annoying 10:1 ratio completely, but if you eat plants yourself, at least you only run into that ratio once, rather than twice or more (as happens when you eat meat). Thus, vegetarianism can result in a Highly Significant reduction in the amount of resources required in order to keep oneself fed. Im sure the popularity of vegetarianism will greatly increase once they solve a few niggling problems, like how can Homo sapiens manage to acquire all of their vital nutrients from a 100% meat-free diet.
But I digress.
Ten pounds of prey biomass to one pound of predator biomass: You can argue about whether the relevant number should be 10 or 12 or 8 or whatever, but the underlying you need a lot more prey notion strikes me as a fundamentally sound concept which applies to pretty much any ecosystem. And in view of human experience here on Earth, it seems pretty clear that the presence or absence of an intelligent species doesnt do anything to obviate that 10:1 ratio! And with all of the above said and acknowledged, its reasonable to ask how the cultures and/or civilizations of non-human sophonts will be affected/influenced by that 10:1 ratio
Perhaps the most obvious such effect: Intelligent herbivores will tend towards higher population levels than intelligent carnivores. This follows from the fact that it takes more resources to support a carnivore than it does a herbivore, hence it takes fewer meat-eaters to ram up against the innate carrying capacity of a given plot of land. However, dont forget that the 10:1 ratio applies to total biomass, not total number of individuals! Its not unlikely that a civilization of 50-kilogram carnivores could have a higher population than a civilization of 10-ton herbivores, after all. But all else being equal (that is, assuming comparable body masses & etc), Larger Numbers Of Herbivores is the way to bet.
Both herbivores and carnivores are capable of over-running the carrying capacity of whatever land they live onbut they wont necessarily do it in exactly the same way. Faced with a food shortage, intelligent herbivores will seek out plants which they wouldnt otherwise have eaten; this is not unlike how normal cattle will eat grasslands down to the bare dirt if theyre allowed to. Bad karma all around. As for intelligent carnivores, they arent directly concerned with that green leafy stuff, and so its at least possible that the ecological aftermath of a carnivorous species population explosion could be less damaging to the land than would a herbivorous species.
One might think that intelligent carnivores would be less likely to form larger social groupings than are intelligent herbivoresmany carnivores are solitary by temperament, after all. But on the other hand, there are also a number of carnivores that hunt in packs, so the isolated carnivore thing is hardly a given. Its a much better bet that carnivores social groupings will be smaller than those of herbivores, if only because of the likelihood of smaller total population, with solitary being the extreme case within the general category smaller.
One interesting (and indirect) consequence of all the above, is that carnivore societies are likely to display a lower level of innovation than are herbivore societies. For any critters in which the distribution of intelligence is described by a Guassian curve, a larger group is likely to have both (a) a larger number of high-IQ type, and (b) within that high-IQ subgroup, a higher absolute upper limit for intelligenceand as noted earlier, herbivore cultures are likely to be more-populous than are carnivore cultures. In addition, smaller social groupings mean a smaller total number of interactions with other group-members, which, in turn, means less opportunity for the kind of intellectual cross-fertilization that comes with free exchange of ideas. In other words: Intelligent carnivores are likely to have less in the way of high-end brainpower than herbivores, and those brains are likely to produce fewer novel ideas, as compared to intelligent herbivores.
Okay, thats enough for now. I could easily have continued on indefinitely, but youve got to stop somewhere, and this is as good an endpoint as any. But note what I did: Starting with a basic fact of ecology, I ended up with some plausible ways in which that basic fact could affect nonhuman civilizations. If I actually developed this further, into a real setting for a real story, I probably wouldnt include any of the above text in the story itselfbut everything I actually did write in that story would be affected by the ideas in the above text. And the cultures in that story would be strange, alien to humankind, but also comprehensible and self-consistent. And its all because I asked the next question!