Evolution, Brain Scans, and Just So Science Stories

When it comes to trying to answer questions about human nature (or even human behavior) scientifically, our reach consistently exceeds our grasp. Often times what we believe is a new understanding of the world is, at best, a theory, and at worst speculative imaginings meant to bolster a certain world-view. A chronic offender in this regard is Steven Pinker, who is, in fairness, an excellent explainer of the latest science of the mind. His book How the Mind Works is, overall, very helpful in walking the lay person through these issues. However, the later chapters are marked by an effort to rope that science into supporting a materialist ideology, a flaw that is much more in evidence in his shorter writings, like this New York Times article on morality, when he expounds upon where our altruistic impulses might come from:

Community, the very different emotion that prompts people to share and sacrifice without an expectation of payback, may be rooted in nepotistic altruism, the empathy and solidarity we feel toward our relatives (and which evolved because any gene that pushed an organism to aid a relative would have helped copies of itself sitting inside that relative). In humans, of course, communal feelings can be lavished on nonrelatives as well. Sometimes it pays people (in an evolutionary sense) to love their companions because their interests are yoked, like spouses with common children, in-laws with common relatives, friends with common tastes or allies with common enemies. And sometimes it doesn’t pay them at all, but their kinship-detectors have been tricked into treating their groupmates as if they were relatives by tactics like kinship metaphors (blood brothers, fraternities, the fatherland), origin myths, communal meals and other bonding rituals.

That entire paragraph is a great example of what I call (with all credit to Rudyard Kipling) Just So Science Stories. In Kipling's book, of course, fanciful yet plausible explanations are given for how animals ended up looking as they did. The elephant got his long trunk by a crocodile pulling it, the leopard got his spots from a hunter who put dark fingerprint smears on his fur to help him blend into the shadows. Just so with Pinker: we have a sense of community because our kinship detectors are tricked by wordplay and having dinner together. I suppose that could be true, but it certainly seems a lot like he's trying hard to make challenging data fit a one-size-fits-all explanation: your genes did it! Here is a great retort to Pinker:

If Pinker could break out of his evolutionary innate approach to human capacities, he would be able to explain more easily why people reason so differently about pushing someone over the edge versus having a train run someone over.

Lakoff makes a central distinction in how people think about causality, of billiards-ball causality versus human action.  We treat billiard-ball causality and human causality as very different things.  And for good reason, since this distinction builds from everyday experiences and is mediated by language and cultural models. There is a dramatic but quite real difference between pushing someone off a ledge and watching some people get run over.  In the latter case, the train—that massive billiard ball—is the immediate cause of death.  But pushing?  That’s human doing, and it lights up all sorts of systems in the brain that generally light up when people think about doing stuff and what that might mean in the real world.

That last quote alludes to bran scans, another area where Just So Science Stories seem to be told with impunity. It seems like once a week I'm reading an article touting the latest amazing finding from these windows into our brains. And yet, all too often, all these studies have really proved is that certain stimuli tend to make neurons in a certain area of the brain activate at higher levels. Susan Krauss Whitbourne, a Professor of Psychology at UMass Amherst, brings some needed skepticism to these studies:

Brain scans are clearly an advance over phrenology, but they also have their limitations. The biggest problem is that we can't precisely localize specific brain functions. Though it's possible to speak in general terms of a "reward center," it's not possible to pin down the exact nature of which reward goes with which set of neurons. Neurosurgeons discovered many decades ago that there is redundancy in the brain and that there are substantial variations from person to person.

It's important that think hard about these studies, because pretty soon we're going to be asked to make societal decisions based on their findings. For example, scientists have begun to look at whether criminal behavior may be linked to underdeveloped or damaged areas of the brain. They point to reduced brain activity in parts of the brain that, they say, are important for regulating emotion, and link this to poor impulse control that leads to crime. This could potentially be used to argue that certain criminals aren't culpable for their acts. But should we make this leap based on the number of neurons firing in a person's brain, without understanding why those neurons are or are not firing?

Let me make an analogy. Brain scans are creating a visual representation of the brain's electrical activity. We could similarly make a heat map of a car, which would light up most around the engine, and much less so around the person driving it. But drawing the conclusion that the engine then determines where the car goes would, of course, be completely wrong. And our heat map would almost completely miss the GPS system sitting on the dash, which might be more significant in determining where the car goes than even the driver. Similarly, parts of the brain that light up on scans might not be the only parts that contribute to a certain behavior.

We all like direct, satisfying answers to the big "Why?" questions in life, but we have to maintain our skepticism to avoid falling for trendy, persuasive, but ultimately false or incomplete Just So Stories.