Wednesday, September 30, 2009

The Evolutionary Psychology of Andrea Yates

The Texas woman who drowned her 5 children in a bathtub has been on my mind nearly non-stop since my husband, Mr. Field Notes, was told by his new psychology prof that evolutionary psychology has nothing to say about the case, because her genes died with the kids, whereas the other perspectives of psychology do.

I have been trying to keep from going bananas about it. After all, he is only taking the class to satisfy a dumb prerequisite required for what he really wants to study. And it's only a dumb requirement because he already has a much larger knowledge of psychology than most students who take intro retain even after 6 months.

So anyway, he started taking an introductory psychology class online through our local community college and I didn't have high hopes that it would actually be a good class, and I agree that he should just do the minimal effort required to get an A and leave it at that.


When the prof so summarily dismisses my field's perspective so early on, it sort of slams the door on that perspective being seen as valuable from there on out. I just don't like the foundation it sets for the rest of the class and he can, if he chooses to, defend the perspective and show that it actually has some value, not to mention increase everyone's knowledge. I don't know if he will speak up in the class discussion forum where it came up, but I kind of hope he does.

If I were him, I'd argue that Andrea Yates killing her kids is an example of female infanticide and that under certain circumstances, killing your own progeny can increase reproductive success. It wouldn't at first glance seem so, but evolution is not as simple or as black and white as it appears.

A woman who has a lifetime of reproductive years ahead of her and has a baby that is unhealthy, sick or disabled, or for whom she is unable to care for due to life circumstances such as poverty, lack of support, or ill health herself (including mental illness), may 'choose' to kill that child (or children) and try again for a healthy one or postpone having children until her situation changes so that when she does have another child, the child will have a better chance of actually surviving long enough to reproduce. By doing so, she cuts her losses and saves wasted energy.

Rarely do other animals continue to care for sick or disabled offspring. And, there are examples of animals, primates even, that postpone their reproduction until their circumstance becomes more favorable for reproduction. Tamarins are a great example of this. Often, the reproductively mature offspring of these small South American monkeys stay with their parents and take care of their younger siblings instead of moving away to start families of their own. They could move away from home, get 'knocked up' and try to take care of those babies on their own in an area where they cannot adequately defend enough territory to have food to eat and a safe place to sleep, but they don't. And they don't go off to have those babies, realize they made a mistake, kill the babies and try all over again when they can find a place with food and shelter. Instead, they don't even bother moving out; they stay put and become adult babysitters. They invest in the genes they share with their siblings and bide their time until they can successfully raise a family of their own.

We humans don't seem to be very good at delaying reproduction until better times even with access to condoms and birth control. There are plenty of news reports of babies found in the toilet and in garbage bins, and of course, humans have plenty of abortions. There are also plenty of examples of women who wait until they're done with school and have a career and an established social support system before they start a family (and sometimes they wait a little too long and find their fertility has dropped, making this strategy not entirely foolproof either).

My point is that people kill their own kids, more often before they are even born, and while it seems counter to evolutionary theory for them to do this since it kills their genes, it doesn't kill their ability to produce kids. They can still reproduce in the future and if being motivated to kill your kids under the right circumstances means that your reproductive success isn't zero, i.e. you still have a child that survives to reproduce later, then the genes that contribute to that motivation haven't been selected against. The only thing that would truly be inexplicable from an evolutionary perspective is why people would get a vasectomy or have their tubes tied before they ever reproduce. And even that can be predicted by evolutionary theory if those people tend to contribute to the reproductive success of their relatives, with whom they share many of the same genes.

In any case, evolutionary theory would predict that a woman would be most motivated to kill her own children if:
* They are severely sick, injured, or physically or mentally disabled to the point of being unlikely to reproduce as adults,
* She lacks the financial, emotional or social resources (social support) needed to effectively care for them,
* The woman is young enough to have a better chance of successfully reproducing later than if she continued to care for the child/children.
In such cases, the benefit could outweigh the cost. For the behavior of Andrea Yates to be a perfect example of this, she would have had to be younger than 45 (an age at which there is a significantly reduced chance of being able to become pregnant) and be poor or depressed or socially isolated or have ill or disabled kids. She was 36 at the time, young enough to be able to reproduce again, and from the Wikipedia account on her, sounds as though she had little social support to help care for the children, and was convinced the children were defective.

Steven Pinker, a respected evolutionary psychologist, argues in his book How The Mind Works, that post-partum depression is a mechanism that motivates a woman to kill her newborn in just these circumstances. It has been said that Andrea Yates had been experiencing post-partum depression.

I don't think Andrea Yates is a perfect example of the 'kill your kids to bide your time and reproduce again when conditions improve' strategy, but she does fit the bill for an individual who would be expected to be motivated to do so.


Sirius Scientist said...

I've actually heard this argument in several different situations, and it was the first thing I thought of when I read the first paragraph. Thanks for a more thorough explanation.

Very interesting topic!

Anonymous said...

I think the evolutionary insight that is available can explain many things to us, and it can lead the way to new kinds of insight and prevention.

For instance, if all mothers and people understand how they are susceptible to these kinds of extreme stress behaviors they could recognize the signs and seek proper help.

In my own experience when I fell into certain behaviors, less than desirable coping mechanisms sprung up. I can conclusively state that once I began to understand this field I began to eradicate all of my behavior problems by seeking the circumstances and resources my psychology needed to reverse these states of mind.

Thanks for sharing, came to this article googling on the recent tragedy near Edmonton