Nature vs. nurture, round #2,437, 896

Here we go again. There's another report claiming to find a link between human behavior and the environment — in this case, lead supposedly makes you violent.

The problem with studies like these is that human behavior is incredibly complex. It's an interplay of both nature (something in our genes or our environment that favors a particular behavior) and nurture (something in our culture or our upbringing that favors a behavior). It's almost never a clear-cut cause-and-effect type of thing.

Oh, and then there's a little something called "free will" or "individual responsibility." But, because you can't measure it, some researchers seem to pretend it doesn't exist.

Your Comments, Thoughts, Questions, Ideas

bryan kennedy's picture

After doing some research on this subject, I cannot find any reference to the "clear-cut cause-and-effect" you seem to be saying the researchers have declared. I think these studies only present corelations with violent crime in populations with higher levels of lead poisoning. Lead is a deadly poison which severely affects the nervous system in humans and other animals. Studies as far back at 1943 show a corelation with lead poisoning and violent behavior.

"Lead has been shown to increase aggressive behavior in humans in repeated studies since at least 1943, when doctors at Boston's Children's Hospital first noted a tendency toward 'cruel impulsive behavior' and 'irritability' in children exposed to lead."

I think this research can help us to possibly focus more attention on the need to eliminate harmful sources of lead from our communities, since it may have harmful effects on a societal level.

posted on Tue, 02/22/2005 - 12:15am
Gene's picture
Gene says:

I should have been clearer. Sorry.

The point I was struggling to make was, these stories are often presented and understood as "science has found THE cause of X" or "THE gene for Y," and that's simply not true. Even some scientists are guilty of this -- B. F. Skinner and his followers were notorious, as I recall.

Just to say, we've got to take these reports with a grain of salt. And while lead may very well contribute to violence, I believe that there have been stronger correlations found with poverty, education, and even youth. But even then, these are merely propensities; the act of violence is still a personal choice.

posted on Tue, 02/22/2005 - 12:27am
bryan kennedy's picture

Agreed on all points. Science is often presented as the ANSWER, when any seasoned scientist knows that our world is far to complex to have any cut-and-dried answers.

posted on Tue, 02/22/2005 - 12:49am
Jan's picture
Jan says:

You make good points about the complexity of cause as it leads to effect. Your closing comment regarding "personal choice" seems to me to undo all that by implying that choice is a straightforward and simple causal notion. What constitutes "free" or "personal" choice is incredibly complex, and all the causal factors you discuss impact our ability to act freely.

posted on Sun, 04/10/2005 - 6:51pm
shelly's picture
shelly says:

Do you have specific evidence stating that science has found the cause of x or y chromosomes not true. I have not been able to find any real facts of this being said

posted on Mon, 11/28/2005 - 7:37pm
Gene's picture
Gene says:

Hey, I thought this was the "Science Buzz," not the "Philosophy Buzz! ;-)

You are absolutely right -- there are a lot of factors that go into every action. But I can can oversome those factors, or I can succumb to them. At the end of the day, I decide how I am going to act, and I must take responsbility for it.

If some Packer fan gets in my face and ticks me off, I may have a dozen factors impelling me toward violence: I may be drunk, I may be emotional, I may have a personal or cultural background that encourages violanece, I may have some "violent" genes, I may even have lead in my system. None of those things forces my fist to go flying into the guy's face. That's my choice, and my responsibility.

Now, there are some cognitive scientists (folks who study intelligence and information) who claim that free will is just an illusion. Everything else in the universe is mechanistic -- it can be explained by cause and effect, even if those causes can sometimes be extremely subtle and complex -- so what makes us think our brains are any different? On the other hand, there are six billion people alive on the globe today, all of whom experience free will. That's gotta count for something.

posted on Mon, 04/11/2005 - 4:23pm
Gene's picture
Gene says:

I'm not sure I understand your question. Human beings have 23 pairs of chromosomes. One of those pairs, the "sex chromosomes," determines whether you are male or female. It comes in two varieties: X and Y. Women have two X chromosomes; men have one X and one Y.

So, X and Y chromosomes are real. But you can't really say "science has found the cause" of any chromosomes.

(In the post you responded to, I used the phrase "the gene for Y" not to mean "the Y chromosome," but to mean "some random behavioral trait." I was also arguing that such a statement is a dangerous oversimplification. I apologize if I wasn't clear.)

All 23 pairs of chromosomes have many, many genes (no relation). Many of these genes help the body create proteins or other molecules.

Science has found many genes which code for specific molecules. If a person is missing one certain gene, they will not be able to produce the insulin the body needs. If they are missing a different specific gene, they will not be able to produce pigment for their skin and hair. And so on.

It's rarely a case of a single gene working alone, however. Often, many genes have to work together for something to happen.

Behavior is even trickier. There are no genes for behavior, only for proteins. However, science has found that certain chemicals which genes create may make some behaviors more or less likely. A faulty gene may fail to produce a certain chemical, and people with that feature may, on average, be more likely to be violent, or fearful, or whatever.

However, there are lots and lots of chemicals in the body, and they interact in ways we are only beginning to understand. Plus, as I mentioned in my earlier posts, there are many external factors as well -- education, culture, poverty, etc. -- which have as great or greater influence on behavior.

All of which is to say, science has never -- and probably will never -- point to one specific gene and say "This gene makes you violent." What science CAN say, and has been able to say in many cases, is "people with an error in this gene are, on average, more likely to..." whatever. But individual action is still a matter of individual responsibility.

posted on Wed, 11/30/2005 - 12:02pm
shelly's picture
shelly says:

sorry to not be that specific. I think I found what I was wondering anyways. I've been researching a paper for college on violence and nurture vs. nature. I was seeing lots of study reports by scientists saying that they had believed that certain inherited rates, such as an extra y chromosome where connected to a tendency to engage in criminal behavior. I was wondering if they had proved that theory wrong or right. But I have found in a book the words, "Research on the possibility of a link between criminality and an extra y chromosme has some relationship but can not be demonstrated." That's all i was wondering. Thanks for replying anyways. You have some very interesting comments.

posted on Thu, 12/01/2005 - 2:02am
Anonymous's picture
Anonymous says:

I am not sure that your answer is correct.

posted on Mon, 09/17/2007 - 9:40am
bryan kennedy's picture

Recent behavioral research in monkeys has shown that abuse of offspring may have more to do with experience (nurture) than genetic makeup (nature). Darius Maestipieri, at the University of Chicago, was able to show that macaque monkeys mothers were more likely to abuse their young when abused themselves. Offspring of abusers who did not grow up in an abusive situation did not grow up to be abusers.
bryan kennedy
Science Buzz Site Admin

posted on Mon, 06/27/2005 - 11:42pm
Dat's picture
Dat says:

Im a high school student, doing a paper on the same subject, and there is one area that none of you have touched on yet, brain dysfunction, i have found a lot of information on how the amygdala effects your behaviour,(it is the part of the brain that controls your "flight or fight responce") and if there is any genetic deformation in the amygdala (condition is called episodic dyscontrol) then a person becomes uncontrolable violent, which i dont think would in fact be the persons faulght due to their own genetic predisposition. my point is that i agree with you that science will never be able to say that there is a behavioural gene but i think that you cant disgard the notion that there are gentic factors that make cause a person be become violent without their control.

posted on Tue, 12/20/2005 - 9:26am
Anonymous's picture
Anonymous says:

Gene you said "Oh, and then there's a little something called "free will" or "individual responsibility."" and "But even then, these are merely propensities; the act of violence is still a personal choice."

I agree with majority of your post(s), specifically it's the environment(family, socity, school) that shapes the person. But here's the thing, Free will isn't all that free. It's true, humans have the ability to make decisions but what brings about that decision is the cause not the person's choice. What I mean is, every decision is based on a person's individual experience/knowledge. So When a person LACKS the CORRECT knowledge, they'll inevitably make WRONG decisions. How can you blame someone for doing something wrong when they don't control what there exposed to or given the knowledge to make the right decisions?

Also, you have to think, why would a person( who is deemed mentally "sane") commit violence? Are you saying people are inherintly evil? Of course not. But the legal system and most of society says well...it was there "choice". That idea seems to be an excuse for punishing "evilness", which itself, is a human concept.

I'll better illustrate my point, Let's say we pluck two boys, roughly the same age, one from the an African tribe who has never received formal education and the other boy from a middle class family from the US with a 10th grade education. Now give them 2 indentical test that covers basic math ,verbal and writing skills, what do you think will results? You don't need to setup to experiment to show anything, it's obvious the boy from the US who has been in school will out perform the other boy from Africa. But why is this? The test clearly stated the "choices" but the African boy who hasn't received any education got almost every answer incorrect while the other boy received a near perfecr score. The Obvious answer is the boy from Africa didn't have the knowledge needed to make a accurate choice. So what have we learned? Those who lack knowledge ultimely make incorrect decisions even if accurate choices are presented because they didn't know understand. So can we hold this innocent child responsible for his incorrect desicions shown on the test? The simple answer is no. If the child was given the chance to live in a place where education was available than he would most certainly done better on the exam. But we as a society punish those who lack the knowledge to make correct choices all the time. And just because you tell a person something is wrong, unless they understand, they will simply ignore it.

I'm not saying to let those who unfortunately commit crimes to be let free and simply say "it's not there fault". Instead, these people need mental help. You can't just throw people in prison and expect the problem to go away( oh wait we do that). Because in prison, a lot of the times, the inmate will be mistreated and come out even worse. Rehabilitaion is key to help prevent violence and unless you remove the root cause of violece, it will never go away.

Now I'm well aware there are some genetic factors that may cause someone to commit violence more than someone else but nothing shapes a person's mind more that he or she's aqcuired knowledge(either consciously or subconsciosuly) and experience.

I've probably repeated myself and ranted way to long but that's my view or at least a part.

posted on Sat, 12/24/2005 - 3:58am
Gene's picture
Gene says:

I'm sorry -- I missed this post when it first arrived.

Are humans inherently evil? Well, I was raised Catholic, so there is the idea of Original Sin. ;-) I do believe that people will always act in their own best self-interest, and we need to be taught that cooperation, altruism, and simple good citizenship / good behavior will, in the long run, be better for us than non-stop greed, ego, and instant gratification.

Your analogy is a good one, but because it mixes cultures it doesn't quite fit. Let's try this: take two children from the same US school system: one a first-grader, the other a high-school student. Give them both an algebra test. We would expect the high school student to do well. We would expect the first-grader to do poorly, for the very reason you mention -- they had never been taught algebra.

But what we're talking about here is not cognitive knowledge, but violence. And by the time a child is old enough and strong enough for their violence to be a threat to property or to others, they should also have been socialized to the point where they know it is wrong to use violence; that violence may seem like a quick solution to an immediate problem, but in the long run it actually causes a lot more difficulties.

In systems analysis, one always looks for proximal causes and distal causes. Proximal causes are those immediately at hand -- a Packers fan getting in my face after a tough loss. Distal causes are the things you've touched on -- education, acculturation, poverty, limited options, limited experience, etc. These are things that are not part of the immediate situation, but rather are part of the background, part of the person's make-up. Some you have more control over than others. The original post noted that science wants to add some more, like lead or genes.

My point is, you can have all the distal causes in the world, but there isn't going to be any violence unless you respond to the proximal cause with a punch.

Getting back to the classroom analogy. We would not expect a first-grader to do as well on an algebra test as a teenager. The first-grader hasn't been taught. But if we gave the test to two teenagers, and one got a 90% and the other got a 60%, then one would get an A and the other would flunk. You can blame a poor school system, but the bottom line is both had been taught.

Similarly, we would not expect a first-grader to handle their emotions as well as a teenager. The little guy is more likely to cry, or to lash out. They haven't been taught to behave. But by the time you are 18, you've been taught how to behave. You've certainly had many opportunities to learn. If you choose not to behave (or chose not to learn), it's your fault. You flunk.

I agree with you that the prison system is deeply flawed and often does more harm than good.

posted on Mon, 09/17/2007 - 12:45pm
Anonymous's picture
Anonymous says:

Good job though, i support you.

posted on Mon, 09/24/2007 - 11:23am
Anonymous's picture
Anonymous says:

I have a question for school to answer that I'm not quite sure how to, maybe someone can help...State the two sides of nature versus nurture, and in what sense are human nature and nurture not opposed to eachother?
Thank you sooo much...Savannah

posted on Sun, 09/24/2006 - 10:28pm
Anonymous's picture
Anonymous says:

does the environment you live in affect your ablilty to learn?

posted on Tue, 03/04/2008 - 2:46pm

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