Sunday, June 05, 2005

Science and Teleology part IV

This is the forth installment of an essay where I have been discussing the relationship between science and teleology. In the previous installment, I continued to explore why animals play. It was determined that play is a type of learning behavior but that this wasn't quite the teleological answer that we were looking for. I ended the installment by asking what the advantage of learning is. I also stated, somewhat cryptically, that this was the wrong question but for the right reason.

The question I asked is misleading. It is misleading because conflates learning and play. Although we have determined that some animals play to learn, it does not follow that all animals play to learn. In fact, the ability to learn, unlike the behavior of play, is fairly common. Mice, famously, can learn to navigate mazes. Pigeons can learn to play tic-tac-toe (or knots and crosses if you prefer) and can do a decent job of it. Even nematodes (simple worm-like creatures) can be trained to take a right hand path at an intersection so as to avoid a shock.

It is, however, the right question in the sense that we need to consider what advantage learning confers; however, we also need to understand what differentiates the sort of learning that happens during play and to determine what advantages are conferred there.

The advantages of learning may seem self-evident but we should bear in mind that the vast majority of organisms do not and cannot learn for the simple reason that most living beings on the planet don't have brains. This has not inhibited the success of bacteria, plants, fungi, various protozoa, various algae and slime molds, nor a number of animals such as sponges and star fish. In like manner, many animals that do have brains have such simple brains that they can not learn new behavior including arthropods (insects, spiders, crustaceans, etc), and the majority of mollusks (with octopi and squids being the notable exceptions).

We might suppose that the ability to learn is a good survival strategy when it comes to dealing with complex environments and this supposition would, in fact, be true; however it isn't the only strategy nor is it always the best one. Small creatures tend to adapt to shifting environments by simply breeding fast and copiously. Many larger organisms, such as trees, cope by assuming forms that are extremely durable. We should also be aware that not all environments are equally unstable. Many environments are very stable of long term periods which allows for survival strategies that "assume" that any given life will experience a given set of circumstances.

When it comes to thinking about animals it's often helpful to think in terms of something called a protein budget. A protein budget is simply the amount of raw material that you have to work with when creating a given organism. The "you" in question is nature and we can think of this in terms of natural selection or, if we are so incline, in terms of a god (it really doesn't matter in this case). Your one and only goal is to make creatures that can survive long enough to reproduce.

The main thing you need to understand is that you have a finite amount of material to work with. That's your protein budget. You can spend it on things like claws, or wings, or brains, or sophisticated eyes, and so forth and so on. Like any budget, you can only buy so much before you run out of funds, which means that you have to spend your allocation wisely.

Brains can be expensive and they aren't always the best deal. If your animal can manage to do without them, you should probably spend your funds on other things. Even if you opt to buy a brain, you can't always afford to get the best model. If your animal's brain is taking up so much of your budget that your animals can't successfully defend itself, you've made an unwise purchase. In the natural world, animals that have "budgeted" badly go extinct.

The reason that we find brains in the natural world is that they do come with quite a few advantages. While it is possible, in many circumstances, to get along without brains, having a brain does improve your interactions with the world. High-end brain models not only improve your interaction but allow you to modify your interactions over your lifetime so as to continually improve your survivability — if you can afford it.

Not all animals have an equal protein budget. Insects get a very small budget and have to be especially conservative in their spending. Larger animals, such as reptiles, have more latitude. They can afford to spend a big chunk of their budget of some relatively sophisticated brains. But even in big animals, there's always the question of trade-off. Do I benefit from having a bigger brain or by spending it on something more practical. Dinosaurs, famously, had a literally huge success by spending the bulk of their budget on bulk. Being bigger was more useful to them then being smarter (and make no mistake, dinosauria was an immensely successful order of animal).

So let us say that we have decided to budget for a brain and that we've opted for a learning model. We still have a critical question to ask: what sort of things do we want to learn. Here is where we really need to start thinking about the disadvantages of learning. Yes, disadvantages.

Creatures are born into a hostile world. There are an immense number of ways to die. You can fall off a cliff, you can be crush under a bolder, you can be eaten by a predator, you can be killed by a sexual rival (or a mate: just ask a praying mantis), you can succumb to disease, you can eat a poisonous plant, and so forth and so on. Although the ability to learn from mistakes can be useful (mustn't eat those particular berries again; they got me sick!) having to learn everything is a disadvantage.

Imagine being an antelope and having to learn that lions are predators. Your first lesson would probably kill you. If you are an antelope, it's a lot better if you know, from the start, that lions are dangerous. In other words, you're better served, in this case, by having an instinctual aversion to lions.

An instinct is nothing more than a pre-programmed set of behaviors that are hard-coded into the structure of the brain. They are, essentially, "memories" that you are born with.

We humans tend to disdain instincts. We consider them something primitive that has been superseded by our capacity to reason. We have every right to be proud of our rational abilities but our tendency to see them as being an natural advantage is a bit anthropocentric.

Again, we need to think in terms of budgets. This time, instead of a protein budget, we need to think about a neural budget. Any given brain will only have so much space. Any amount that we budget for learning is going to subtract away from the space that we can allocate from instinct (and vice versa).

If I am an animal that is being born into harsh circumstances it is typically to my advantage to come into the world with as many instincts as possible. Instincts tend to be necessities while learning tends to be a luxury. It is often a good idea to budget some space for the capacity to learn, of course. If I am a mouse, there's no way that instinct is going to prepare me for the particular configuration of tunnels that I'm going to have to traverse. Being able to learn tunnel layouts (or mazes) is a very useful trick, so I'll need to budget some brain space for that. As a rule, though, it's a very good idea to be born with as much survival gear as possible, which means a bias towards instinct over learning.

When most animals learn, what they learn are things that supplement their instincts. Few animals need to learn the basic elements of survival, such as how to walk. The only animals that can afford that are those who are shielded from those basic necessities.

Does this ring a bell?

In the previous installment we noticed that animals that engage in play tend to have long development times. I called this "developmental luxury". Those animals that are shielded from most of the dangers of their environment can afford the luxury of dispensing with some of their instincts. They can afford to take the time to learn how to do the things that other animals are born knowing how to do.

This still doesn't explain why they would "want" to. We are still left wondering what the advantage of learning how to do things that we could, in principle, be born knowing. Why not keep those as instincts?

We're still asking the wrong question. The right question is why can't we keep those as instincts. This question will be the subject of the next installment.

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