The incomparable Fred Reed, whose polite orneriness I have great respect for, recently posted a column with some questions about evolution: “Me, Derbyshire and Darwin”.
Being broadly accepting of the theory of evolution myself, while disdaining the way the term “evolution” has been turned into a cheerleader’s chant that one team in American politics uses to assert their superiority to the other, I feel I am well placed to offer some answers to Fred’s questions, even though they were largely directed to Derbyshire. The full-length questions can be found on Fred’s page, and I will merely provide one-line summaries of them here to assist the reader in keeping track of which one I am answering at any given time.
1) What selective pressures lead to a desire not to reproduce, and how does this fit into a Darwinian framework?
Organisms don’t necessarily feel a desire to reproduce, in itself. There’s a layer of indirection here: In the past, those people who found sex pleasurable tended to have more sex than those who did not, for obvious reasons. As contraception was rather haphazard in those days, sex would frequently lead to children. Thus, the Darwinian framework could select for the desire to have sex, because it’s much easier to keep track of whether one is engaging in pleasurable activity (i.e. having sex) than whether one has taken silphium recently. The appearance of reliable condoms and similar devices happened an eyeblink ago in evolutionary terms – only about four generations – and has yet to spread worldwide. In the short term, a surprise move like contraception can trump evolution, because evolution is a weak process playing the long game.
One could fruitfully compare evolution to gravity on this point: a common fridge magnet is overcoming gravity, with some help from friction. A child’s sucker-dart fired to the ceiling and sticking there is overcoming gravity by suction, but I expect it to fall down eventually. “Eventually” in this context may of course be far longer than the child is willing to wait to get his dart back, necessitating the acquisition of a ladder. When I lift a cup, I am also overcoming gravity, but it would be tiresome to do so indefinitely, and I cannot overcome gravity for every object in my household at once. In the long run, and where I am not exerting effort, gravity will likely have its way – and so too with evolution. If things continue in their present course, our species might, for instance, develop an instinctive horror of contraception – because if those with that horror have fertile sex, fifteen children and live in a shack, and those without it have mostly sterile sex, two children, and live in a nice condo, future humans will mostly be descended from the former, though this might take a thousand years. But for the moment, our mind and will run amok, proliferating traits most contradictory to evolutionary principles, and doing things that evolution hasn’t gotten a chance to react to yet.
2) Why should I not indulge my hobby of torturing to death the severely genetically retarded?
Evolution can’t provide much of an argument against this. Prudence might suggest that you should limit yourself to dysthanizing your own severely genetically retarded family members, particularly under conditions where manpower is plentiful but resources are scarce – because if you go off to torture to death someone else’s retarded relative, that someone else might object on the grounds that they’d still rather have a retarded family member than the unrelated you, and try to torture you to death in response. But this still only holds under conditions of extreme resource scarcity – in most cases, it’s “better” (very very crudely speaking from a genetic-interest standpoint) to instead use the genetically retarded as cannon fodder or something, rather than kill them off outright.
I feel it is worth stating here that “evolution” is to a great extent an after-the-fact description of what happened and what worked. “Evolution” did not make one creature have more offspring than another; “evolution” refers to the result that the first creature’s genes were copied more times than the second creature’s genes. Anthropomorphizing or reifying evolution is a convenient mode of speech when saying something like “evolution selected for this trait“, and a more accurate phrasing would go along the lines of “In the relevant population under consideration of organisms with or without this trait, those organisms with the trait had higher proportions of offspring surviving to reproduce than those organisms without the trait, over a sufficiently long period of time that the accumulated reproductive differential overcame chance“. Phew, that’s a mouthful.
3) How many years would have to pass without replication of abiogenesis, if indeed it be not replicated, before one might begin to suspect that it didn’t happen?
No idea, and the question is somewhat out of bounds for evolution, which mostly deals with the development of organisms over time, not their origin. But it might be happening outside our notice. The First Critter, by hypothesis, came into being in a vast lifeless sea, in which nothing existed that could prey on it. It was probably quite incompetent, as newcomers usually are, so the empty sea must have been a blessing. These days the descendants of the First Critter are presumably a lot more badass, and likely to eat any Second Critter resulting from another case of abiogenesis. Perhaps there were even Third, Fourth, and Five-Hundred-Seventeeth critters replicating abiogenesis, and they all got slurped up by a blue whale, which eats eight thousand pounds of krill a day and would be unlikely to notice if it also slurped up a primitive critter which had just abiogenesis-ed into existence.
4) What are the viable steps needed to evolve into a creature with a multi-step, metamorphosing lifecycle?
I don’t know the specific answer, but I think starting from the butterfly is taking the hard case first, something which is often a recipe for confusion when trying to reason about a subject.
Consider instead that everything developing from an egg is, in principle, a creature with a multi-step lifecycle. At one point it’s only a few cells large and suspended in fluid; later it’s much larger with well-defined limbs and breathes air. Every creature not assembled at scale has to grow in some way from an infant form which lacks the full parts of the adult form, and having those parts grow in is the easier option than having the parent assemble them manually.
Once that begins to seem normal, I’d move on to the tadpole, which undergoes a similarly drastic transformation to the butterfly, but a far more gradual and well-understood one. After first being an egg, it’s then a lump with a long tail, before undergoing another change of losing the tail and growing tetrapodal limbs. But, again, the parent does not construct these limbs. They grow out of the tadpole by nature, and from an egg-tadpole-egg cycle (which would resemble a tiny kind of eel) I find it easier to see how some tadpoles could evolve another step of growing limbs.
Finally I would consider the role of specialization. A hypothetical ancestor of proto-butterflies might not have such a sharp divide between steps of its lifecycle. Instead, it might be a centipede-like creeper with weak glider wings through all its life. When great amounts of nutrition are available, the creeper can grow its wings more. Gradually a pattern develops where the creeper will binge-eat immediately before mating season so as to use its wings for greater mobility during that season, increasing its chances of a successful mating. Then it specializes for use of wings during mating season; it ceases to be born a glider, but the wings only grow out once it has binged. Now, the creepers have something like “puberty” where their wings emerge. Then they start to create protective coatings at the start of puberty to protect their newly-sprouted wings, and they have invented the cocoon. Now we are almost to a butterfly, and the next step is perhaps flight from predators driving the evolution of larger and stronger wings.
I stress that this is merely hypothetical and speculative, but at least it suggests to me that there can exist a viable path of evolving from centipede to caterpillar to butterfly.
5) Does not genetic determinism lead to the paradox that we’re not actually thinking about genetic determinism?
The full text of this question suggests to me two subjects which deserve to be answered separately.
I tentatively reject genetic determinism when it comes to abstract thought, as part of a wider impression that one must implicitly reject the determinist-physicalist-nihilist-materialist-reductionist complex of ideas to discuss any ideas without implicit absurdity. This rejection was first argued that I’ve seen by CS Lewis in Miracles and more formally propounded by Plantinga. For an extreme example of the contrary point of view one has Alex Rosenberg in volumes such as The Atheist’s Guide to Reality, which is an exercise in practical bullet-biting: it argues that our thoughts aren’t about anything, we have no thoughts, there is no “we” to not have thoughts because we are merely the inexorable workings of physics and chemistry, and even “there is no we” is meaningless because it’s a positive assertion which might be true or false, and the inexorable workings of physics and chemistry don’t deal in true or false. This is contradicted in yet another way by Alrenous of Accepting Ignorance, who takes the position that there’s thought and consciousness all the way down to the chemical level, albeit quite small amounts of it. Opinions on this topic vary.
When it comes to walking and talking, though, genetic determinism is partly true, but incomplete. One has to ask “relative to what?”
If one asks relative to Fred Reed, for instance, knowing the genetic programming of a wolf lets us predict the vast majority of the different behavior the wolf is likely to engage in, such as walking on all fours and never speaking English.
Knowing the genetic programming of a typical Lithuanian citizen gives us less information about how this person will behave differently relative to Fred, but still some information.
Finally, knowing the genetic programming of Fred’s hypothetical brother gives us almost no new information – we could have guessed much of it from Fred’s genetic programming, and the differences between the two will be mostly non-genetic.
6) Why do seemingly trivial traits proliferate while clearly important ones do not?
For several reasons, among which are (a) nature disagrees what is trivial or important, (b) it’s a random process that takes time, and (c) traits cluster, rather than proliferating a la carte.
Under (a), there are two sub-points. The first is tradeoffs. The brain, for example, constitutes less than five percent of the body by mass, but uses twenty-five percent of the body’s energy. It’s the first thing to go in emergencies – malnourished children wind up retarded before they wind up crippled. In short, it’s a resource hog. Stephen Hawking’s intelligence is like buying your sixth car: very nice, I’m sure, but is it really the most productive use of your money? I’m sure you could afford to raise more kids if you were to get a nanny or something instead, which brings me to sub-point two: payoffs. The importance of 20/5 vision, in evolutionary terms, is measured by how many more children, on average, it gets you compared to 20/20, which doesn’t seem like all that many. Stephen Hawking’s intelligence may have played a part in his having three children, which is above his present-day, local average of two, but at the time he was born, the world-wide average for number of children had was about five. I’m told that in Niger, one has an average of seven children. To evolution, it would seem that being Nigerien is presently more important than being Stephen Hawking.
As for (b), the randomness of the process was quantified by the very clever fellow J.B.S. Haldane. Suppose a new trait appears, which provides its bearers with P percent more children, on average, than those who don’t have the trait. Then the chance of this trait eventually proliferating to everyone is approximately 2*P, to a maximum of one hundred percent. Thus a trait which gives its bearers an average of 10% more children has only a 20% chance of proliferating once it appears, and an 80% chance of disappearing. Hence the “noise level”. Evolution doesn’t perfectly pick the best things, merely picks better things more often in proportion to how much better they are – and if the margin of differential success is less than about 0.003%, it rounds off to randomness, because about 0.003% of our genes mutate every generation anyway, providing the base material for later selection.
(c) is mediated in several ways. The most famous one is perhaps the chromosome – one of 23 pairs of big lumps of genetic material, which is mostly copied as a unit during reproduction, and thus brings several traits as a group or none, providing trivial traits with a free ride of sorts. Even when a single gene is cross-copied separately from the chromosome, that gene might work to increase the production of a hormone (say, estrogen) that has different effects in different parts of the body, or affects the operation of multiple other genes.
 For those unsatisfied with the 2*P approximation, http://rsif.royalsocietypublishing.org/content/5/28/1279.full has detailed equations.
7) What is the reproductive advantage of crippling pain (migraines can be crippling) about which pre-recently, the sufferer could do nothing?
I see no advantage to the crippling pain itself. I speculate that it might be a side effect of the pain system not only existing in the first place but having been toned up in response to people blithely ignoring lesser pain, much as I must regularly dismiss every day a dozen popups, dialog boxes, and tooltips on my computer telling me that my computer wants to restart, my java needs updating, my cookies are out of date, and one of my applets has frozen. (Whose brilliant idea was it to use all these culinary terms in computing, anyhow?)
It provides reproductive advantage for the pain system to be very attention-grabbing in the first place to warn us that we are sticking our hands in a fire, which is a really bad idea, and we should stop RIGHT NOW. But once this system is in place, there’s a possibility that it might be malformed or get damaged in some way, and will overload and send pain signals for no good reason. So on the whole, having the system is better than not having it, as one can see with leprosy, which damages the sensory and nervous systems, diminishing the feeling of pain – but God, at what cost!
8) If one believes in or suspects the existence of God, how does one exclude the possibility that He meddles in the universe?
One doesn’t. But there’s a sort of etiquette which suggests that it’s ‘impolite’, for lack of a better word, to invoke the possibility that God was meddling without a good reason to suspect this in the particular case. If I lose my watch, I don’t put this down to an act of God, except in the abstract sense that the creator of the universe is indirectly responsible for every event that happens in it, including me losing my watch. I should rather put it down to my own forgetfulness, or perhaps a petty thief. Maybe the cat did it. Even the possibility that the neighbor’s cat came over and knocked my watch off the desk before stealthily fleeing the scene is more respectable than jumping directly from a missing watch to divine intervention. Perhaps it’s something I haven’t yet thought of, and it would be intellectually lazy of me to say “God did it” without better reason.