In works on evolution written by a certain class of biologist we can often see “for the good of the species” references derided in no uncertain terms. Comments such as “fuzzy thinking”, “they got it wrong” and so on have become so habitual that they almost go unnoticed. But is the “for the good of the species” idea really all that bad? It might well be that some comments and discussions are indeed fuzzy, in that they might be poorly thought out or presented. But here’s a discussion from Robert Ardrey’s The Social Contract to consider. Ardrey described the communication between starlings as an element in their defence against peregrine falcons, the falcons being hindered in their attacks by the speed for which they are famous. It turns out that they are so fast that they can only attack prey in the air, as contact with the ground, however slight, would cause injury. This also means that they cannot attack groups of birds; they can only target isolated individuals.

“At such speed, should anything go awry and the falcon strike its prey with a wing instead of its talons, the wing will be broken. And so, through the ages, starling and falcon have perfected their relation to the nicest of balances. Sighting a hovering falcon, the most alert member of the starling flock gives the instant alarm call. Now all crowd together nearly wingtip to wingtip, and begin their unpredictable mass manoeuvres. There is no leader. Somehow all participate in a common sense as to what the next swerve or dip will be. The falcon of course dares not dive. So perfect is the starling social defence that any attack would be suicidal. And so he waits, hovering. And natural selection takes its toll. If one of the hundreds of massed birds has weakness of wing or fails in some fashion to sense the next turn, then it is separated from the flock and the falcon has it. And the unequal starling will leave no further descendents to encumber the flock’s gene pool. Starling defence illuminates the value of society to a group of unequals. In any given situation of danger one member, whether superior in alertness or simply lucky, will be the first to sense threat. And with the alarm call, the perception of the first becomes the property of the group.”

Now Ardrey is clearly talking here of behaviours that he believes are for the good of the group or the species. So is the argument “fuzzy”? Is the pattern of behaviour he describes for the good of the group, or for the good of those individuals who use the group to avoid predation? It may be impossible to say with certainty. Arguments can be put to support both cases. But it is possible to imagine a scenario in which there is a benefit for the flock and ultimately the species. (Selfish gene theorists will be quite at home with this style of thinking – imagined scenarios are their stock-in-trade.)

Imagine a flock of starlings that are preyed upon relentlessly by falcons. After several breeding seasons the starling gene pool may be altered to such an extent that the flock is able to outlast the hovering falcons. At this point the falcons have to make a decision – seek alternative sources of food or starve. Hardly a choice at all. Now unimpeded by constant harassment, the invigorated flock, stronger, faster, smarter, increases in numbers and thereby comes to dominate the starling gene pool. (Keep in mind that the “arms race” argument whereby as the prey becomes more efficient at evasion the predator becomes more efficient at predation, does not always apply. If an alternative food source can be accessed with less effort expended than in hunting starlings, the alternative will become the food of choice.)

Clearly such an outcome, overcoming a predator, is good for the group. Clearly also, while we cannot predict where, when, or how such an outcome will eventuate, processes similar to that which we have imagined have occurred in evolutionary history.

So for critics of “for the good of the species” thinking, it seems it’s all bad news. The concept appears valid. But then, they could have worked that out themselves.

Let’s take our hypothetical flock a little further. Able to outflank predators at every turn, their numbers double, then treble. All is well until famine hits the region. Their food supply drops below the level needed to sustain their greater number. The question now arises, is sudden death by predation as in former times, preferable to a slow death by starvation? And what behaviours will the flock display as it struggles with this new reality? Will they remain a unified whole and migrate to new domains? Will they split into smaller groups and disperse randomly? Will they be forced by the defences of other groups to remain where they are until their numbers drop to sustainable levels? The possible outcomes are countless, but a question keeps nagging in the background. Was their defeat of the falcons truly a victory; was it good for the species in any lasting sense? For that matter, is it possible in evolutionary analysis to even use the words “for the good of”?

There is one thing of which we can be sure. No starling, no matter how fast or strong, can survive alone against its normal range of predators. Of all the options available to deal with a changing environment, the successful option will involve group activity of one type or another. Ernst Mayr once said that there are no laws in animal behaviour, there are only regularities. (Let’s call that Mayr’s Law!) This is one such regularity.