I just finished reading “Why Evolution is True,” by University of Chicago Professor Jerry A. Coyne — and I highly recommend it.
This outstanding book was written as an answer to those who say “there is no evidence for evolution,” and as such you’ll find it mentioned anywhere the science education culture wars are fought. Coyne did a great job really laying out all the evidence and showing how it dovetails, etc., so if you are interested in the topic of evolution and want to know more about the evidence, this is your book.
I’m writing about it here, though, from a slightly different angle — that of a writer of fantasy and science fiction who often has to imagine strange and bewildering creatures to populate his fiction. Coyne’s book really kicked my brain into overdrive.
For one thing, Coyne’s book provides solid tangential evidence for life on other planets. Coyne doesn’t say that or try to make that case, but he carefully outlines evolutionary processes and left me with the impression that life and evolution are pretty much inevitable, given the right conditions. The right conditions, of course, probably exist in many places in a universe as old and vast as this one. A science fiction writer needs to take that into account. It doesn’t seem plausible these days to postulate a universe where life is exceedingly rare, or is a surprise discovery by mineral miners on some distant world. Nope. Intelligence might be rare indeed, but life? Probably not.
For another thing, the book makes it quite clear that evolution can build almost any kind of creature. If you can imagine it, evolution probably can produce it. That’s rather freeing, in a way. If you are writing fantasy or sword & sorcery, you may not care too much whether your fire-breathing flying squid or bullet-spitting avian reptile is particularly plausible, but if you are writing science fiction you probably care very much.
After reading Coyne’s book, I’ll bet that the simple yet complex processes of evolution could produce a fire-breathing flying squid or a bullet-spitting avian reptile, under the proper conditions.
Understanding the evolutionary process can help you create those fictional monsters. Evolution doesn’t build things wholesale; it enhances and modifies previous models. So, to build a bullet-spitting avian reptile, you just have to play a fun mind game and figure out the steps.
We’ll concentrate on the bullet-spitting, since we already know evolution can produce flying critters. I’m picturing a winged beastie that spits high-speed projectiles at prey on the ground, rendering it dead or at least incapacitated. How could such a weird ability evolve? (If all the stuff below seems mentally unbalanced to you, blame me, not Jerry Coyne …)
Maybe it started with a creature that swallowed small stones and stored them internally in a gizzard, slowly absorbing moisture or minerals from the swallowed stones or using them to grind food. We have fish and birds right here on Earth that do that, by the way. In our made-up creatures, let’s say the swallowed stones, once deprived of whatever use the creature gets from them, are regurgitated and replaced.
It’s not an assault weapon yet, but the basics are there. Stones come in and go out. What we need now is environmental impetus and millions of years. Natural selection will do the rest.
Choking on stones is bad, so natural selection would likely favor critters with powerful lungs and wide necks to make sure stones get out. Critters with necks that are too skinny or lungs that are too small would be more susceptible to choking, and thus less likely to pass on their genes, etc. Over time, our avians would get a bit bigger to improve lung capacity.
We don’t have a living gun yet, but we’re closer. If you want to make the bullet-spitting plausible, you’ve got more thinking to do. Perhaps our avian reptiles, in getting bigger, get slower as well? Maybe they aren’t as adept at swooping down on the little mousy things they eat. Maybe the little mousy things dart under roots or into holes and our bigger avians can’t get to them in time. Being bigger and slower might be detrimental in other ways; for instance, it might make it easier for beasts on the ground to pounce on our avians and eat them.
So our avians develop a new hunting technique — dropping stones on their prey. They scoop up a good-sized stone, perch on a branch overhanging a rodent traffic zone, and let fly when they see a meal scurry by. Then they drop, grab their stunned mouse thing and get back up to a nice safe branch.
OK, it’s not the most efficient approach imaginable, but it’s a big universe and weird stuff happens all the time, so hang with me a little longer. Consider that some of our avians would be better at this hunting technique than others. Natural selection would favor keen eyesight and quick reflexes. A longer, pointier bill would probably help, too, as far as aim and sightlines are concerned. Over time, the avians as a population likely would evolve to be physically better at this hunting technique.
It’s still a rather inefficient technique, though. The avians have to land somewhere, gather a stone big enough to stun or kill a mousy thing, then lift it up to a perch and hang onto it until food wanders by. That’s rather tiring, and a lot of bother. But remember that enhanced lung capacity to help get the swallowed stones dislodged safely? That windpipe-and-lung combo could add some ooomph to a stone attack, allowing a smaller, less cumbersome stone to strike prey with enough force to do the job. Avians with bigger gizzards could hold more stones. If those same stones, swallowed for an entirely unrelated purpose, can be projected with sufficient speed to stun prey, then a bigger gizzard means more stored ammo, and thus less time gathering ammo, and more time hunting from nice safe branches.
From this point, it’s not hard to imagine our winged avians that spit stones with decent accuracy and decent force evolving into winged avians that spit a slew of stones with amazing accuracy and enough force to prove lethal to a human planetary explorer. Indeed, I unleashed such critters on my players in a Traveller RPG game a long time back. At the time, they were just imagined monsters — I knew how they worked, but had no idea whether such things could plausibly exist. Now, I think maybe they could.
I leave it to you SAB readers to figure out how to evolve a fire-breathing flying squid. Feel free to do so in the comments below.