In the prior installments of this essay I introduced the concepts of teleology and etiology and their relationship with science. In the last essay, I advanced the proposition that science can approach some teleological questions and proposed that the phenomenon of play was one such area. I finished by conducting a partial survey of life forms, eliminating the vast majority of organisms from consideration. At the end of the installment, I had limited the scope of inquiry to mammals and offered the reader the challenge to see if they could determine the unifying factor that links those mammals which do play.
I suggested that you might want to start with a random sample of mammals. So you might have come up with a list something like aardvarks, bats, cats, elephant, horse, mice, mole, sloths, etc. You might then have divided them into animals that are known to engage in play (cats, elephants, horses), animals that don't (aardvarks, bats, moles, sloths), and animals that you might not have been sure about (say, mice).
On any comprehensive list there are going to be questionable cases. We must first decide whether or not we can, in fact, categorize such outliers. In my list, I put mice in the questionable column. The reason that I did so is that mice in captivity often do seem to engage in play like activity. I know one girl who had a group of mice that would all get on their spinning wheel, run it up to a high speed, and then grab on to the wheel's frame which caused them to get spun around on the inside of the wheel (which, if nothing else, proves that mice don't suffer from motion sickness). That certainly seemed like play; however, a wheel in a cage is not a natural environment. It is well established that many creatures will exhibit anomalous behavior when put into unnatural circumstances. Do mice in the wild exhibit playful behavior? I haven't been able to find evidence that they do. So, which column should mice fall into?
There are any number of inaccurate stereotypes concerning the workings of science and not all of them come from the detractors of science. Many people who are "pro-science" have a notion that scientists will scrupulously include all experimental data in their considerations. In principle, it is true that data shouldn't be discarded on the basis that it contradicts a given hypothesis, but this isn't quite the same as saying that all data is automatically going to be included. This isn't always so.
Let us suppose that I'm conducting experiments on the effects of various salts on the boiling point of water. I set up a traditional experiment where I have a control (several beakers of distilled water) and an experimental set. I conduct a series of measurements for salt X and find that in nineteen trials the boiling point clusters closely around 102.7 degrees centigrade. In the twentieth run, however, my thermometer reports a boiling point of 131 degrees!
If we were to follow the stereotype, I would dutifully record the data point on my carts and adjust my curve to fit it in. In practice, though, I know damned well that 131C is not a real boiling point. Perhaps my instruments have a defect, or maybe there was a patch of superheated steam that threw of the thermometer. Whatever the case, I know to a high degree of certainty that the measurement is meaningless. I can do one of two things at this point. I can either exclude it from my data entirely or include it in the data and discount it from the conclusions.
Modern practice favors the latter. Modern science is a very competitive venture and anything that could even potentially look like data manipulation can be used to destroy one's career; however, whether or not I plot the data in my submission, it would be equally irresponsible for me to allow it to impact my results and doing so would also get me into hot water (if you'll pardon the pun). Given this, I'll note the outlier but I will specifically say that it is an outlier and that it isn't included in the calculations for the actual data curve. It should be noted that many respected experimentalists from the earlier days, when science was more of a gentleman's hobby, didn't bother to do that much. Bad data was tossed out on its ear without any hesitation.
So, having dispensed with the outliers, for the time being, let us look at the data and offer some tentative hypotheses.
You may have noticed that there seem to be a lot of carnivorous animals on the list: wolves, lions, hyenas, and so forth. Could it be that being hunted is the factor that we are looking for? But what about elephants and horses, who are both herbivores, as well as primates, which span the gamut from strict vegetarians (gorillas) to predatory omnivores (such as chimps and, yes, humans).
Clearly there is more to the matter than diet, however, before we more along too hastily, we should note there are, in fact, a lot of carnivorous predators and periodically predatory omnivores. Should we, perhaps, consider the herbivores on the list to be outliers? In this case, I think not. There are enough herbivorous creatures that we can't simply dismiss them from consideration without running the risk of skewing our answer. What we need to do is to think about what commonalities there exist between the predators and the non-predators on our list. We should, however, consider the predatory bias to be a clue.
My goal, here, is to give you an idea of how scientific inquiry works. The fundamental point that I want to convey is that science is systematic. Too many people have an image of science where a scientist takes a look at some new phenomenon, ponders it briefly and then, from the vastness of his intellect, produces just the right insight to explain it. As much as so-called eureka moments are celebrated, real science is a grueling and often tedious exercise where observation after observation is tested against one tentative hypothesis after another. Even the grant theorists such as Einstein had to consider mountains of prior observation and theory before producing their own. The public, too often, sees science as a sequence of facts that are provided on demand. They don't see the working process that is responsible for the production of those conclusions.
For the purposes of this essay, I'm providing an abbreviated account of the considerations that we should be examining. If this were a real scientific investigation, we should be considering dozens, if not hundreds, of alternatives and we should be using more than a random sampling of mammals as our dataset. Fortunately for us, I'm following a trail that has already been laid out by the real workers. Because they have put themselves to the effort of being systematic, I can afford a certain degree of laziness.
I would like you to take a final moment to consider the data, however, before moving on. Consider what we have and ask yourself what commonality binds play.
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As it happens, there are actually two factors that are almost universally present in animals that play. The first factor is that animals that play are not born with a full set of mature behaviors. The second factor is that the behaviors that they engage in while playing resemble behaviors that adult animals employ in non-play activities.
Let us consider a wildebeest calf, a lion cub, an elephant calf, and a human baby. The first does not engage in play while the latter three do.
When a wildebeest is born, the very first thing that it needs to do is to stand up. The reasons for this are very good: a calf that cannot stand on its own four legs is in serious danger of being eaten by passing carnivores. One of the most horrific videos that I've ever seen was a mother wildebeest with a half born calf being torn to shreds by hyenas. Clearly, time is of the essence.
A lion cub, by contrast, has a strung resemblance to a domestic kitten. It is born blind and feeble. Likewise, so is a human baby. An elephant calf is somewhere in the middle. Elephants are very protective of their young, and they have the bulk to back up their protectiveness, so an elephant calf isn't at high risk of being eaten by the local fauna. On the other hand, elephants require a large foraging area and have to move fairly large distances to eat. Elephants, unlike lions, can't create a crèche for their offspring, and they can't carry them from place to place, as humans can do, so a baby elephant needs to get her feet under herself fairly soon.
This represents something that we might call developmental luxury. A wildebeest does not have the luxury of being born unable to walk, nor does an elephant, but a human and a lion don't have to be born with those capabilities. We have, so to speak, the luxury to take our time to develop those capabilities. This is a very big clue, by the by.
Let us return to our wildebeest. Our wildebeest is not only born knowing how to walk. She also knows how to forage, how to spot predators, and how to stay with her herd. She also has a set of behaviors that cause her to remain close to her mother and which prompts her to nurse on a periodic basis (as do lions, humans and elephants). As she matures, she will lose these while gaining certain sexual behaviors (again, as will lions, humans and elephants). This, for the most part, represents the whole of her knowledge set. Wildebeests don't need to know a lot in order to be successful. A wildebeests life may be occasionally stressful (you try being on someone's lunch menu) but it is not a complicated life.
Our lion cub, on the other hand, is going to need to know how to hunt, which means not only knowing how to chase down animals but also how to select favorable targets and how to coordinate their kills with the other members of their pack. There is also a range of non-hunting behaviors that lions need to develop which also relate to their pack structure. A lion needs to be able to discern its place in the pack hierarchy and to know how to behave with respect to other members in the pack.
Elephants, obviously, do not hunt and there's not much that they need to know about foraging (plants are docile prey). This is not to say that an elephants mental space is small. We humans have an expression, "as plain as the nose on your face", which means that something is obvious and simple. If elephants had language, that expression would be an oxymoron. Baby elephants are not born with well coordinated trunks (just as human babies don't have well coordinated limbs and fingers). They can get away with this because they are highly social creatures and their mothers can help them along until they get their trunks under their full control. Elephants also have a fairly complex social structure which they need to integrate with.
Humans, of course, are the most complex case. A human child is born without control of her body, knowledge of her society, any skills, or even language. By the time she becomes an adult, she must acquire all of these things.
Let us call this feature developmental complexity. Although our three examples have the luxury to be born with less than a full compliment of behaviors, they also have the obligation of developing a behavioral set that is substantially more complex than their wildebeest peer.
Before we continue, I want to head off a potential red herring. Elephants, humans, and lions are social creatures. You may be tempted to suppose that this is the critical ingredient; however, many playful creatures are solitary. Most species of cat, for instance (including domestic cats and tigers) are non-social. Socialization isn't irrelevant but, like carnivorousness, it isn't the whole shebang.
Returning to the topic, you may have noticed that there is a word that I haven't been using. That word is "learning". I've been avoiding it because it is the final clue. Animals that play are animals that are born knowing less than they know about the world (developmental luxury) and which have a lot that they will ultimately need to know about the world (developmental complexity).
Play behavior is synonymous with learning behavior. Juvenal animals play in order to learn how to be adult animals.
At this point you might suppose that we have our teleological answer. We are not quite there, yet, unfortunately. We have one more question that we need to address: why do some animals need to learn anything in the first place? In other words, what's the advantage of learning?
I will leave this for you to ponder this until the next installment. I will give you a clue though: I'm deliberately asking the wrong question, but for the right reason.
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