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Genes, Murder, and Bad Driving

Can crimes and crashes be blamed on bad genes?

On Friday, Nature reported details of an Italian case in which a court, for the first time in Europe, reduced a criminal sentence based on a genetic theory of behavior. According to the report:

Pietro Pietrini, a molecular neuroscientist at Italy's University of Pisa, and Giuseppe Sartori, a cognitive neuroscientist at the University of Padova, conducted a series of tests [on the defendant] and found abnormalities in brain-imaging scans and in five genes that have been linked to violent behaviour—including the gene encoding the neurotransmitter-metabolizing enzyme monoamine oxidase A (MAOA). A 2002 study ... had found low levels of MAOA expression to be associated with aggressiveness and criminal conduct of young boys raised in abusive environments. In the report, Pietrini and Sartori concluded that [the defendant's] genes would make him more prone to behaving violently if provoked. ... On the basis of the genetic tests, Judge Reinotti docked a further year off the defendant's sentence, arguing that the defendant's genes "would make him particularly aggressive in stressful situations". Giving his verdict, Reinotti said he had found the MAOA evidence particularly compelling.

Scientists interviewed by Nature say this kind of genetic determinism is too crude and tenuous to justify sentence reductions. Genes operate in relation to each other, not independently, and they produce different effects depending on environmental factors and population differences such as ethnicity. My colleague Dan Engber, who alerted me to the Nature report, has made similar points about brain scans and neuro-determinism. I'm highly sympathetic to his indictment of the field.

Despite these criticisms and the skepticism of judges, Nature reports that according to a database maintained by Nita Farahany of Vanderbilt law school,

in the past five years there have been at least 200 [U.S.] cases where lawyers have attempted to use genetic evidence to support the idea their clients' were predisposed to violent behaviour, depression or drug or alcohol abuse. In Britain, there have been at least 20 such cases in the past five years.

And don't be surprised if the next target of genetic determinists is car crashes. Neuroscientists from the University of California at Irvine have just laid out the case in a paper in Cerebral Cortex, accompanied by a catchy press release. The release is titled, "Bad driving may have genetic basis, UCI study finds." It reports:

People with a particular gene variant performed more than 20 percent worse on a driving test than people without it—and a follow-up test a few days later yielded similar results. About 30 percent of Americans have the variant. ... The driving test was taken by 29 people-22 without the gene variant and seven with it. They were asked to drive 15 laps on a simulator that required them to learn the nuances of a track programmed to have difficult curves and turns. Researchers recorded how well they stayed on the course over time. Four days later, the test was repeated. Results showed that people with the variant did worse on both tests than the other participants, and they remembered less the second time.

The release explains how the gene works:

This gene variant limits the availability of a protein called brain-derived neurotrophic factor during activity. BDNF keeps memory strong by supporting communication among brain cells and keeping them functioning optimally. When a person is engaged in a particular task, BDNF is secreted in the brain area connected with that activity to help the body respond.

The study, funded by the National Institutes of Health, will surely become fodder for defense attorneys in civil and criminal cases involving crashes or dangerous driving. And these lawyers won't be alone in their interest. In the press release, Steven Cramer, the neuroscientist who led the study, says, "I'd be curious to know the genetics of people who get into car crashes. I wonder if the accident rate is higher for drivers with the variant."

I bet every auto insurer would like to know the same thing.

I'm counting on Engber to pick apart the study and the press release. Let's hope the authors are oversimplifying the impact of genes on behavior. Because if the link between genes and driving performance is solid enough to justify reduced sentences and damage awards, it's hard to see why insurances shouldn't be allowed to test and charge you accordingly.

Race, Genes, and Criminal Justice

Is it OK to guess a perpetrator's race and appearance from DNA found at the crime scene?

A few weeks ago, Gautam Naik of the Wall Street Journal updated us on a fertility clinic's program to screen embryos for "eye color, hair color and complexion." The clinic hoped to use a method that could supposedly "identify [genes] that relate to northern European skin, hair and eye pigmentation in 80%" of IVF embryos.

Two weeks later, when the clinic suspended the program, I suspected its concession was more technical than moral. Predicting traits from genes is hard. That's one reason why so many threats and promises of genetic engineering haven't materialized.

But now it seems I may have underestimated the field. Naik has returned with further research on the genetics of appearance. Gene-trait correlations are becoming increasingly precise. And the practice to which they're being applied most aggressively isn't embryo screening. It's law enforcement.

Here's his latest report:

Murray Brilliant, a geneticist at the University of Arizona, is developing a predictive test for skin, eye and hair color. Supported by a grant from the U.S. Department of Justice, he and his colleagues recently analyzed DNA material provided by 1,000 university students from different ethnic backgrounds. They found a total of five genes that account for 76% of the variation for hair color, 75% for eye color and 46% for skin color. Similarly, scientists from Erasmus University published a paper in March in the journal Current Biology based on a DNA analysis of 6,000 people in the Netherlands. For that population group, they found that only six DNA markers are needed to predict brown eye color with 93% accuracy and blue eye color with 91% accuracy.

Some of those numbers are quite impressive. If they're packaged into an affordable embryo test, I guarantee you buyers will start lining up. But look where the money's coming from. Brilliant got his grant from DoJ. The Erasmus group got its funding from the Netherlands Forensic Institute, which "provides services to clients within the criminal justice chain, such as the Public Prosecution Service and the police." In fact, Naik points out, "[t]he push to predict physical features from genetic material," known as "DNA forensic phenotyping," has

already helped crack some difficult investigations. In 2004, police caught a Louisiana serial killer who eyewitnesses had suggested was white, but whose crime-scene DNA suggested—correctly—that he was black. Britain's forensic service uses a similar "ethnic inference" test to trace murderers and rapists. In 2007, a DNA test based on 34 genetic biomarkers ... indicated that one of the suspects associated with the Madrid bombings was of North African origin.

Whoa, there. Do we really want cops hunting for people of a particular race or ethnicity based on uncertain inferences from a DNA sample? Apparently several states don't. Nor does Germany. These jurisdictions, according to Naik, forbid "the forensic use of DNA to infer ethnicity or physical traits."

I understand the concern. But these prohibitions are a mistake. DNA forensic phenotyping doesn't need to be perfect. It just needs to be better than—or a substantial way of double-checking—the unscientific inferences we already make.

The Louisiana case sets off racism alarms because DNA phenotyping said the culprit was black, whereas witnesses said he was white. But that isn't the usual pattern. Decades of research suggest that a witness is more likely to misidentify a person as the perpetrator when the accused person is of a different race. And according to the Innocence Project,

Racism continues to be a significant cause of wrongful convictions. While 29% of people in prison for rape are black, 64% of the people who were wrongfully convicted of rape (and then exonerated through DNA) are black. Moreover, most sexual assaults nationwide are among perpetrators and victims of the same race (the federal government says just 12% of sexual assaults are cross racial), but two-thirds of all black men exonerated through DNA evidence were wrongfully convicted of raping white people.

DNA phenotyping didn't invent the problem of erroneous racial inferences in law enforcement. That problem is as old as racism and lives on through mug books, lineups, and eyewitness testimony. As the Innocence Project points out, DNA is beginning to clean up the problem. Granted, DNA phenotyping isn't nearly as reliable as DNA matching. But is it really worse than relying on witnesses alone? At the very least, wouldn't it be useful and wise to check witness recollections of the perpetrator's race or ethnicity against a DNA phenotype analysis?

The same goes for facial features. Naik reports:

Mark Shriver, an anthropologist and geneticist ... [is] trying to construct a "picture" of a person's face by analyzing DNA. He calls the technique "forensic molecular photo fitting," and it is supported by a $500,000 grant from the U.S. Department of Justice. ... His team collected DNA samples and photographs from 243 people ... and used computer techniques to correlate the genes with his subjects' facial features. They have found six genes that seem to influence such traits. One gene is associated with the height of the face; another is associated with its width. Yet another gene affects the shape of the lips and the nose. By piecing together these elements, Prof. Shriver hopes to create a modern-day version of the police artist sketch.

Initial results of this method will probably be pretty crude. But will it end up being worse than old-fashioned police sketches based on eyewitness accounts? Would we have caught the Son of Sam killer earlier, for instance, if his police sketch hadn't been wildly inaccurate, making him look Latino or Asian?

No, DNA phenotyping isn't perfect. But it's better than nothing. And it's better than trusting witnesses alone.

Blacks, Gays, and Michael Steele

Four months ago, this column looked at the overwhelming black vote for California's Proposition 8, which banned same-sex marriage. Why would one group, having endured discrimination, vote against the rights of another?

Answer:

Whites, on balance, have come to believe that sexual orientation, like color, is immutable. Blacks, on balance, haven't. They see homosexuality as a matter of character. "I was born black. I can't change that," one California man explained after voting for Proposition 8. "They weren't born gay; they chose it."

Here are the numbers:

In a 2003 Pew survey, 32 percent of whites said homosexuality was inborn, 15 percent said it was caused by upbringing, and 40 percent said it was a lifestyle preference. Latinos answered roughly the same way. But only 15 percent of blacks agreed that homosexuality was inborn; 58 percent said it was a lifestyle preference. A plurality of whites (45 to 39 percent) said a person's homosexuality couldn't change, but a two-to-one majority of blacks (58 to 30 percent) said it could. The pattern persists in Pew's 2006 survey. A plurality of whites said homosexuality was inborn, and a majority said it couldn't be changed. A majority of blacks said that homosexuality was just how some people preferred to live and that it could be changed.

Now comes Michael Steele, the new chairman of the GOP. Steele is black. In an interview with GQ's Lisa DePaulo, Steele concedes:

Q. Do you think homosexuality is a choice?
A. Oh, no. I don't think I've ever really subscribed to that view, that you can turn it on and off like a water tap. Um, you know, I think that there's a whole lot that goes into the makeup of an individual that, uh, you just can't simply say, oh, like, "Tomorrow morning I'm gonna stop being gay." It's like saying, "Tomorrow morning I'm gonna stop being black."

This matches what the nation's leading black Democrat, Barack Obama, has said. In a November 2007 appearance on Meet the Press, Obama declared, "I do not believe being gay or lesbian is a choice."

This is very bad news for opponents of gay marriage. As Proposition 8 demonstrated, blacks have become politically pivotal on this issue. If they follow Steele and Obama in coming around to the idea that being gay is like being black, look out.

More on Sports Genes

I forgot to do something Monday that I need to start doing from now on: posting an item here each time I write a longer essay in Slate. The item here will just link to the essay and summarize it. Or maybe it'll just be the opening paragraph or something. The reason I'm doing this is to simplify things so you don't have to go to two different places, or subscribe to two different RSS feeds, to get the latest Human Nature whatever. Last spring I set up a network of separate HN pages. Result: The more clicks readers had to go through to find each page, the lamer the traffic got. My tentative conclusion: You're busy, and you don't have time to go poking around looking for a lot of stuff, and my job is to make it easier for you to find what interests you in one place. So: Here it is. You can read the short stuff here, and the longer stuff, and eventually we'll have blog software that will let me post more links to outside pieces, in case you're into that.

If you want to RSS this page, you can use the RSS or Atom links on the right. Or you can bookmark it using the URL at the top: http://www.slate.com/blogs/blogs/humannature/default.aspx. Or, for those of you who prefer a URL that's easier to remember and type (as I do), I just bought humanature.com (one N—all the double-N humannatures were taken), so you can just type "humanature" in your browser window, hit control-enter, and it'll bring you here.

Now, here's the link to Monday's piece. It's about a test that's being marketed to parents to tell them which version of a "sports gene" their kid has. I called this an early version of environmental eugenics or "envireugenics." The language guardians at Commentary have already criticized this as a misnomer and an "ugly Greco-Latin hodgepodge"—the sort of response that, when I've delivered it, has prompted my wife to dismiss me as a "usage pedant." So clearly I'm among friends.

Misha Angrist, the delightfully acerbic "Genome Boy," has also posted in response, which completes our mutual name-check, since in part I was responding to him in the first place. I wrote in Monday's piece that the company behind the new gene-testing pitch, Atlas Sports Genetics, was peddling "national greatness." Angrist replies, "I suspect these companies are more interested in making a killing than they are in 'national greatness.' " (He also says he'd write to me if Slate were "less covetous of its reporters' email addresses." This I have to take from a guy who doesn't put his name on his site? Misha, the least I can do is trade you my e-mail address for your genome. The reason I don't post it is that I once gave it out to a newsletter for PR companies, and now I spend 10 minutes a day fending off e-mails from PR companies. It's in the mail.)

The problem I keep having with Angrist is that I want to quibble with his interpretations, but I can't find fault with his facts. I'm sure he's right that Atlas is in this for the money. I guess what I'm arguing is that in a situation like this, there are two motives: the private one and the public one. Here, the private motive is profit. The public motive is national greatness. The public motive is the one the company presents to potential customers who visit its Web site. This is literally the only message on its home page: "Finding any great Olympic champion normally takes years to determine. What if we knew a part of the answer when we were born?"

Olympic champ? That's a pretty extreme standard to throw at parents up front. Maybe the company thinks there are a lot of parents who seriously envision their kids winning Olympic events. (I envision my kid's soccer team winning more than one game next spring.) But my guess is that the company also feels some obligation to make its public pitch fit the scientific evidence behind the test. And the evidence doesn't show genetic differences in athletic performance at childhood or even ordinary adult levels. It shows such differences at the level of international meets.

I'm not saying the public motive excludes the private one. It's already clear from Sunday's New York Times story that funneling kids toward national greatness is part of Atlas' business plan. I'm just saying that the two motives can operate in tandem, or at least side by side.

The DNA Defense

In Sunday's Washington Post, Rick Weiss detailed an important and underreported trend: the increasing role of genetics in legal disputes. His reporting illustrates how the march of science and the evolution of law are changing the way we think of ourselves. In South Carolina, the state's highest court overturned a murder conviction based on evidence that the killer acted out of genetically based depression. In Tennessee, a murder defendant blamed his conduct on inherited mental illness. In Georgia, lawyers in a murder case sought tests to determine whether their client had a gene associated with violence. In Arizona, a convicted killer argued on appeal that his attorney should have told the court about a similar gene-based propensity.

How did we get here? Weiss's research suggests a confluence of two trends. One is the habituation of courts to DNA. The growing familiarity of this kind of evidence masks the evolving purposes to which it has been put. First came DNA as identification, basic CSI stuff. Then came DNA as evidence of harm: Plaintiffs sued companies over toxic damage, but their DNA failed to show the toxin's expected effects. Then there's DNA as a cause of disease: In pollution and malpractice cases, courts have tested plaintiffs' DNA to check out the argument that genes, not products or procedures, sickened them. And if DNA explains the past, why not use it to predict the future? HIV tests have already been court-ordered to project victims' longevity and thereby calculate lifelong damages. Genetic longevity tests will be next. In a custody case, one parent successfully demanded that the other be tested for the deadly Huntington's gene. Apparently, the point was to challenge the second parent's fitness.

So, we're already in the business of testing for genes to predict fitness. That brings us to the second trend: the increasing use of biology to assess criminal responsibility. U.S. case law has traditionally discounted perpetrators' culpability in the event of sleepwalking, epileptic seizures, insanity, retardation, or "diminished capacity." Three years ago, the Supreme Court struck down death sentences for teenagers, citing evidence of their "underdeveloped sense of responsibility." Every month, scientists find new correlations between genes and traits such as aggression or mental illness. Just two weeks ago, the Human Nature News roundup flagged a study showing a genetic correlate of ruthlessness. As the cost of genetic testing declines, the temptation to test defendants increases. The persuasiveness of some genes increases as well: The allele cited in the Georgia murder case has subsequently been connected to violence in additional studies.

Put the two trends together, and you're looking at a gradual invasion of personal responsibility by genetic determinism. It's a conceptual shift from thinking of people as subjects to thinking of them as objects. The shift helps defense lawyers who need excuses for their clients' behavior. But it comes at a price: If your client is an object, why should we treat him like a subject?

As Weiss points out, courts already use unscientific evidence of "future dangerousness" to decide which killers should be executed. Genes could hardly do worse at predicting such risks. Weiss cites an Idaho case in which the defendant's genetic "propensity to commit murder" became a justification for executing him. A judge in the Arizona murder case drew the same conclusion about the appellant's "alleged genetic predisposition for violence." If your client's genes made him kill, they'll do it again. So don't expect us to let him live.

Nor should you expect us to protect his DNA from scrutiny under the Fourth or Fifth Amendment. If he's the product of his genes, as opposed to their manager, why should we treat them as his possession? He's their possession. Ditto for self-incrimination: If mental states are products of genes, we don't need his testimony; we just need his DNA. We can't make him open his mouth to testify, but we can make him open it for a swab, which could tell us plenty about his mind.

Are we more than our programming? Ladies and gentlemen of the jury, I leave that question in your hands.