Science: Behavior and Evolution

Washington Post science writer Shankar Vedantam was online at 3 p.m. ET on Monday, July 24 to discuss the psychology behind our political biases and answer questions about evidence that shows humans are still evolving.

Vedantam, who wrote Monday's Science Page feature on human evolution , also writes a weekly series of stories about the psychology and sociology behind news events. This week's piece about political biases focuses on why Israeli and Arab partisans equally blame the media.

You can read more of his human behavior articles by clicking here .

A transcript follows.

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Shankar Vedantam: Greetings everyone. Thanks for joining our online chat to discuss two stories I had in the paper today; one explores why people with strong political beliefs tend to think the news media is biased against them, and the other story shows humans are continuing to evolve, with several changes visible at the genetic level. In the interest of keeping this organized, let's do stories related to bias first, and evolution afterwards. There are lots of questions in line already, so if you haven't spoken up yet, please do so soon!

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Fairfax, Va.: 7/24/06

To: Shankar Vedantam, Washington Post

I believe that the following experience may interest you as it illustrates that the "bias affecting perception" condition described in your article is part of a much broader human trait.

This story occurred almost 20 years ago, when my son was in middle school. At that time, he had great difficulty with spelling words...his spelling even defeated spell checkers.

He was home ill for a few days, so he telephoned a classmate to get the weekly list of ten science vocabulary words that he would be tested on the following Friday. He obtained the definitions of the words, but did not ask for their spellings.

On that Thursday evening, he handed me the list of words and definitions and asked me to read each word so he could tell me the definition. I was able to determine his spelling logic for the first nine words, but his spelling for the tenth word stymied me...I had no idea what the word was. I handed him the list and asked him to say the tenth word. He did. I took back the list and saw that the word was spelled correctly.

In determining what the first nine words were, I had become so adapted to his spelling logic that it had replaced my own, making it temporarily impossible for me to recognize a correctly spelled word. (This, despite my being an excellent speller.)

From this experience, I concluded that it is possible for two people to have to have modes of thought/logic/"world views" that are so different as to be totally incompatible.

-Stephen B. Cohen, Ph.D.

Shankar Vedantam: Thanks very much for the comment and the interesting anecdote , Steve. Psychologists have numerous examples to show that social circumstances and cues can lead to subtle but measurable biases in people. What is interesting about these biases is that people are not aware of them, and will deny those biases if asked. Much new science suggests that our brains are not quite the dispassionate computers as some believe, but organs that are biased by preconceptions, feelings and misperceptions. The story in today's paper found that pro-Israeli and pro-Arab audiences shown the same clips reached diametrically opposing conclusions about bias. Here's an excerpt:

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Pro-Israeli viewers, who watched the very same clips, spotted 16 references that painted Israel positively and 57 references that painted Israel negatively.

Both groups were certain they were right and that the other side didn't know what it was talking about.

The tendency to see bias in the news -- now the raison d'etre of much of the blogosphere -- is such a reliable indicator of partisan thinking that researchers coined a term, "hostile media effect," to describe the sincere belief among partisans that news reports are painting them in the worst possible light. ---

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Rockville, Md.: In the study, was there a neutral party that determined that the news segments were actually unbiased?

Shankar Vedantam: The researchers in both the studies were not trying to determine whether the stories were biased. As the story notes, who would decide? The point is the huge difference in perception between partisans on both sides. The study by Ross used six clips from broadcast TV; the study by Perloff used an equal number of clips that just showed equivalent acts of violence without context. Neutral observers in the Ross study leaned toward the Israeli position, which the psychologist thinks may be related to the fact that public opinion in the US leans toward the Israeli position. The more informed neutrals were, the more they were in the middle. The Perloff study found the neutrals were right in the middle.

Of course, they both pointed out that there is no such thing as a perfectly neutral audience -- as in the case of whether a story is biased or not, who would decide such a thing?

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Portland, Ore.: Hello Shankar,

I have professional interest in human behavioral research, and have been following your excellent reporting for some time now. I'd like to comment on today's article in light of two stories you wrote a little while back: "Social Isolation Growing in U.S." (WaPo, June 23 2006) and "Social Network's Healing Power is Borne Out in Poorer Nations" (WaPo, June 27 2005). The implication of your previous articles is that wellness may be related to the richness of our interpersonal relationships. The increasingly fragmented nature of American life seems to be reducing the number of close friendships we have, and that this may have implications for personal health.

I'd like to bring these two earlier articles into the discussion on the hostile media effect. Of itself, the hostile media effect is nothing new; selective perception been well-studied beginning from the late 1940's. What I find intriguing is the possibility that political polarization may be destroying social ties -- people allowing politics get in the way of their friendships -- and that in turn this may be having health consequences for our society.

In other words, extreme partisanship isn't just bad for the health of the body politic. It's bad for your health, period.

Comments?

washingtonpost.com: Here are the two stories referenced above:

Social Isolation Growing in U.S., Study Says

Social Network's Healing Power Is Borne Out in Poorer Nations

Shankar Vedantam: Thanks very much. As a reporter, I am heavily biased toward letters that praise my work rather than messages that think I am a terrible writer.

;-)

There is clearly a lot of research showing the power of social ties both in the context of mental health and mental illness. The idea that increasing partisanship could be leading to increased fragmentation is provocative, but I have not seen any data on that. Of course, you could also argue that partisanship causes the individual sides to band closely together, and could therefore lead to closer ties, at least with your in-group. I think it is a fair thing (and fairly obvious thing) that partisanship leads to lesser and lesser conversation between the groups, as each side talks increasingly to itself. Media reports that strive to get "both sides" are often the target of ire of both sides, but they certainly provide a forum for conversation with people whom you disagree with ...

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Calgary, Alberta: A beautiful analysis today Shankar.

It's typically bold-faced partisans who claim the news media is owned by their opponents in a debate . . . . and both sides make the claim to establish their "downtrodden" status.

I remember the comical sight of Matt Lauer on NBC being accused of being a left wing media schill one week then someone standing up in the crowd the very next week and accusing him of right wing bias.

I've often said the best, most-enlightened media, in fact, are those accused of bias by BOTH sides.

Shankar Vedantam: Thank you, Calgary. Yet another fine example of a letter writer who really understands quality reporting!

Seriously, the sense inside newsrooms that you are doing your job when you are getting beaten up by both sides is very ingrained. Many reporters wear the fact that everyone hates them as a badge of pride. Of course, that can lead to problems of its own, since reporters are obviously not completely above criticism. Sometimes, one side's criticism may be right! In any event, this story was less about what the media does and more about the curiosities of human perception ...

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Madison, Wis.: Your article on partisan perceptions is fascinating. Has anyone determined if there is a particular personality "type" that correlates with extreme partisan behavior? I tend to see both liberal and conservative (or pro-Israeli and pro-Arab) partisans as opposite sides of the same personality coin. And, pardon my alliteration. Thank you.

Shankar Vedantam: Good question. I don't know of such research myself; I do know that there is a lot of scientifically weak stuff out there on "personality types", so I suppose I would treat this issue with some caution. I also think this may have less to do with particular personalities than with human nature in general: We all care deeply about some things, whether or not they are related to politics, and the research suggests that it is this deep emotional involvement that makes us hyper-sensitive to criticism about the things we love.

Here's an excerpt from the story that speaks to that issue:

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If someone says several nice things about you and one derogatory thing, what sticks in your mind? People who are deeply invested in one side are quicker to spot and remember aspects of the news that hurt than they are to see aspects that help, said Richard Perloff, a Cleveland State University political communication researcher.

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Maryland: Hello Shankar,

Your piece on political bias made some interesting points. But how does this theory of bias perception in political news reporting hold up when say reporting "both sides" of the Global Warming or Evolution debate? In this case the "fair-and-balanced," equally weighing both sides conceit gives falsehoods and deceptions the same platform as the truth. In science there is the truth and everything else, and when you lend as much ink to the other side this, paradoxically for many reporters, is an exercise in biased reporting. Do you believe that objective political reporting should follow different standards than objective science reporting? In this respect, your article is lacking.

Tony Gill

Shankar Vedantam: A very good point. Again, this is a media studies question rather than psychology, but I would be the first to say a reporter's obligation is to the truth, as far as it can be ascertained. It certainly is not a mark of quality reporting -- to pick an extreme example -- to quote six people who say the Holocaust happened and six people who say it did not, in the interest of "balance." When it comes to the science questions you raise, I think it is incumbent on good journalists to report not just what both sides say, but where the preponderance of the evidence is. Fairness and accuracy, not some formula about equal time, is what good reporters aspire to ...

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Chesapeake Beach, Md.: Someone once said if a two scientists or mathematicians were in a room discussing a theory, in the end, one (may) end up saying "you know, you are right--this is the way it works" and adjust his research and views accordingly.

But if two people get involved in a political discussion, there is almost never a meeting of the minds.

Why?

Shankar Vedantam: I actually think you can find lots of examples of scientists who quarrel pretty viciously with each other, and fail to see each other's points of view. Of course, if a problem (say in math) has only a single correct answer, then you have a framework to settle the problem. But as with politics, much of science nowadays is complex, and while scientists may generally agree on an overall issue, there are often heated disagreements about nuances.

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Laurel, Md.: Does the mutual-bias phenomenon suggest that maybe the media are missing "third sides" to debates that do not necessarily have 2.0 sides.

Israel-Hezbollah may seem like a two-sided conflict, but "both of you stop fighting" seems like a valid side, too.

Shankar Vedantam: I would actually argue there are probably more than three sides to most topics ... again, the interesting thing from a psychological perspective is not how many sides you get into a story, but how people will PERCEIVE the story. There is clearly a disconnect when strong emotions are involved ...

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Lexington, Ky.: "Doctor, Heal Thyself." So I ask, What are your political biases? Have you tested your theory on yourself?

Shankar Vedantam: I am going to post a bunch of comments with brief or no comments to allow more voices into the mix, even if I cannot weigh in on all of them.

As to this specific question, I think research like this tells me that I am likely to have biases myself. I often find that when I care deeply about a subject, I feel news coverage of it is inadequate or biased. Some of that criticism may be valid of course -- we can't dismiss knowledge just because it is coming from people who are knowledgeable -- but some of that is almost certainly due to errors in perception. I think the only thing to do is to try to be aware of them, and to make sure you do an especially good job reaching out to people with whom you may personally disagree ... good reporters do that.

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Scott City, Kan.: Mr. Vedantam,

Emory University did a study during the 2004 election using fMRI which showed that political partisans generally do not even pass information through the cognitive regions of the brain but rather it goes directly to the emotional regions, explaining why fanatics rarely change even in the face of new and contradictory information.

John Dean has just released his book, 'Conservatives without Conscience', in which he argues that many conservatives are naturally authoritarian personality types, 'cliff marchers' who will follow party line no matter what.

Today, in the New York Times, Daniel Gilbert, professor of psychology at Harvard, and author of "Stumbling on Happiness", wrote an op/ed piece detailing how human cognitive weaknesses make it difficult for us to realize who actually casts the first stone in a conflict, always seeing our own actions as reactions to the actions of others and others actions as causes for our own.

There are numerous other studies, such as the research done by Dr. Lakoff on 'framing', and 'values quadrant' concept by the people at Environics which suggests that the human mind is quite unable to realize when it is being manipulated, and often says one thing and does quite another.

In light of all this research, and the ideas of such neuroscientists as Michael Gazzaniga and his 'interpreter module' discovery, or Robert Ornstein and his 'Same Old Brain' (SOB) theory of a cranium full of simpleton modules, what hope is there for rational solutions to the problems facing the human race, and how much longer do you think we will be able to evolve before destroying ourselves?

Shankar Vedantam: Lots of big questions, more than I can handle in the time alloted. So let me post it for general digestion. I should say all is not lost; the same "human" emotional errors that lead to biased perception also lead to some of the things that make life valuable -- love and art, to name a couple. So there is still hope!

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Ann Arbor, Mich.: Mr. Vedantam:

Two brief excerpts, then a point:

You state:

"Ross thinks this is because partisans often feel the news lacks context. Instead of just showing a missile killing civilians, in other words, partisans on both sides want the news to explain the history of events that prompted -- and could have justified -- the missile. The more knowledgeable people are, the more context they find missing."

Froomkin reminds, on July 19:

"At a brief press availability, Bush was asked if he was comfortable this going on for weeks. He wouldn't answer. 'I want the world to address the root causes of the problem, and the root cause of the problem is Hezbollah'.

"Bush once again misrepresented a recent statement by the G-8 leaders. As many times as he says his fellow leaders agreed that the root cause of the current crisis is terrorists, the official statement says that 'The root cause of the problems in the region is the absence of a comprehensive Middle East peace'."

My point:

Other than the lonely Froomkin, you will search the coverage in vain for a correct statement of the Rice/Bush distortion crucial to their "root cause" mantra: "No ceasefire w/o cure of the root cause". The true root cause is not the current Hezbollah episode but the deliberate utter neglect, for the last 5 to 6 years, of any real US attempt to broker peace in the Palestine affair (or, as the G8 leaders put the root, "the absence of a comprehensive Middle East peace").

That's the true "root" of the current outbreak of the scandalous civilian carnage in Lebanon -- a benighted MidEast policy conceived by our amateur yet somehow also hubric Sec'y of State. Ignoring the shambles her "benign neglect" strategy has led us to is a classic example of Ross' "Where's the context?" insight. Without context, a patently disingenous Condi takes us ever on, into the utter disaster she has made of our MidEast policy (non-policy), by her shameless recasting of her breathtaking MidEast policy failures as simply explainable as Hezbollah as "root".

Here, context -- that is, stunted press coverage once again (see, e.g., Rice's largely unexamined crucial pre-9/11 failures) enabling the artful dodger Condi to escape her own history -- context (or failure to provide it) is everything.

Lawrence Kelly

Shankar Vedantam: tossing this out for general thought ... (more about the media than psychology)

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Ottawa, Ontario: Do you think that this sort of information or idea can be easily manipulated by the wrong idealistic kinds of people into an idea that we have visited in the thirties and forties and if so what do you think you could do to perhaps counter people who approach your research in such a manner?

Shankar Vedantam: one more ... I am slightly uncertain what is being referred to, so maybe you can clarify?

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Shankar Vedantam: we're just past the halfway point, so what say we take some questions on the evolution story. Today's science page feature talks about how humans are continuing to evolve, as evidenced by changes that are visible in the human genome ...

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Waldorf, Md.: Stephen Molnar's Human Variation states that Australian aborigine's teeth are much bigger than a European's. Additionally, their jaws were bigger, and the wisdom teeth came in at the age of 12 instead of 18+. Also, the aboriginies didn't ever need braces. My daughter had to have 6 teeth pulled because there was no room in her jaws. This is an example of modern day evolution in humans.

Is there evidence that, ironically, we are the animals on earth that are evolving faster than any other animal because we can change our environment faster?

Shankar Vedantam: Thanks for the comment. I actually thought it would be the other way around. Natural selection doesn't occur unless there is selective pressure, meaning some kind of environmental requirement that gives some genes an edge. Given that humans in many countries now no longer face the kinds of selective pressure that our ancestors once did, I would have thought there is less evolution going on. (If we can manipulate our environments, that almost sounds like the opposite of evolution, where species adapt to fit their environments.) Turns out of course that even subtle advantages can show up in evolution; an added 1-2 percent advantage, multiplied by many generations, can create selective pressure to allow some genetic variants to flourish.

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Winnfield, La.: This question may be too simple to take your time to answer. However: The composition of the atmosphere of Earth supports life; hydrogen, oxygen, etc. If such elements are necessary to support life, how did the organisms initially survive, unless the atmosphere changed and adapted to support their existence, from whatever level of development they had attained? And, how did the plant and animal contribution to the process of life support occur? Or, how does one know what the other needs to live?

Shankar Vedantam: This will probably take not only more time, but more expertise than I have at my fingertips. One thing I can say, however, is that the current composition of the atmosphere is not what it has always been. New life forms, including those dependent on oxygen, have evolved as the atmosphere has changed. The changes, in many cases, have been driven by earlier life forms that used what was available in the atmosphere and contributed to the rise of other ingredients. The same idea is at play when people talk about "terra-forming" other planets; it would involve getting some lifeforms on the planet that would eventually lead the way to a more hospitable environment for other species.

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Germantown, Md.: 1. Today's article states that "advantageous genetic changes will quickly spread through the -human]population." How -- presumably because the affected individual will be more likely to survive andreproduce? Aren't we beyond that to a large extent in the modern world. For example, the lactose intolerant individual who might have previously perished because he could not take advantage of a common source of nutrition, will now just make another selection at the supermarket. Likewise, medical advances stave off the effects of diseases so that affected individuals are just as likely to suvive to reproductive age.

2. Could our population in fact be "devolving", at least as to characteristics such as intelligence? Intelligent, career-oriented couples go childless or delay and limit reproduction. Less fortunate individuals, through ignorance, poverty, and lack of access to health care appear seem likely to reproduce earlier, more often, and without regard to supporting social structures, such as marriage.

Shankar Vedantam: The idea that evolution involves some kind of ladder of progress is one of the most pernicious and wrong-headed ideas that have accompanied evolutionary science. As the story notes toward the end, evolution is merely a process of adaptation to the environment; as environments change, species adapt or die (or move or learn to change the environments to their own liking.)

Evolution does not really care about our notions of progress and improvement. (Human attempts to push evolution along based on notions of superiority and inferiority have sadly led to unethical things such as eugenics and the Holocaust.)

Demographic changes could well be one of the areas on which natural selection can act. It is usually difficult to know what will happen ahead of time. It is possible that natural selection could reward those who choose to have larger families (laying waste to the idea that having smaller families is a better thing) or it could lead to the opposite, where smaller families actually have advantages, such as increased odds of survival, especially if resources run dry.

Here's an excerpt from the story:

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Contrary to the popular imagination, evolution is not a linear process that culminates in the triumphal ascent of humans at the top of the genetic heap. The process is analogous to a bush, where twigs and leaves push out in every direction.

When biologists talk about evolution and the survival of the fittest, they do not necessarily mean the strongest, fastest or smartest. Fitness is whatever works in a particular environment, and the new research shows that as environments change, notions of fitness change, too. ---

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Ottawa, Ontario: Sorry Shankar, I guess what I am trying to ask is what do you do to combat people who manipulate your research for the gain of ideals that have little merit such as aryan groups or those that might say for instance Aboriginal people such as myself are being naturally selected out of the evolutionary process. It is something I think we could see a lot of if this becomes even more mainstream that it already is and I see it as a potential rallying cry for the ignorance of society.

Shankar Vedantam: Ah yes, I understand. As I said in the last question, human attempts to read "progress" into evolution has usually led to mistakes. I mean think about it. From an evolutionary perspective, it may make far more sense to be socially adept and warm and loving than to have a skyhigh IQ. Human obsessions with race and social markers usually say much more about us than about evolution. It is better to think of evolution as a bush rather than a ladder, something which pushes out in all directions. When you think of it that way, humans are not superior to the shark, we're both just adapted to our environments. We need more intelligence to manipulate the things we need to manipulate, the shark needs what it has, great power and speed and sharp senses.

Our notions of superiority say more about our biases than about evolution. I have a very funny cover from the New Yorker on my desk showing a lion pointing at an evolutionary chart. Guess which species is right at the top? The lion!

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San Jose, Calif.: Evolution certainly modifies, even transforms, species, but it also leads to branching, as Jared Diamond points out in The Third Ape, and perhaps even more tellingly Richard Dawkins in The Ancestor's Tail.

Is there any research going on to suggest how the species might next branch?

Shankar Vedantam: I don't know the answer. I think it is also fair to say that attempts to guess which way evolution wants to go are often spectacularly wrong!

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Foggy Bottom: In your article, you touch on the changes in ASPM and MCPH1, genes that affect brain development. Could you elaborate on the researchers' response when you questioned them on this? You present them with the possibility that "different populations are evolving different mental abilities" and they respond by saying "it is not possible to say with certainty that natural selection has favored the change because of its effect on the brain." Doesn't this sort of side-step the issue; i.e. even if a gene is selected for one of its effects (e.g. immunity), that doesn't mean it won't retain all of its other effects (e.g. brain development). I'm curious to hear if the researchers appeared comfortable with this component of their research. Obviously, this is quite a volatile issue.

Shankar Vedantam: It is a volatile issue, but more because of common misperceptions about how evolution works (and what it is!) What the data show is there are changes in a gene that is associated with brain development; but as the story notes, it is difficult to say what the change does. Could it be because a group moving to a new environment ended up for some reason with a higher risk of brain damage and the change compensates for it? Could it be because the particular gene does something entirely different in the body and the change has nothing to do with mental ability? Absolutely. Whatever it is, it seems unlikely to me that it would have to do with mental ability at the level most people are interested in. As I said before, evolution doesn't really care abour our norms of better and worse. Mental changes that affect social behavior may be far more important and powerful than things involving the mental ability we worry so much about -- how often has solving a calculus problem in record time saved someone's life?

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Los Angeles, Calif.: I often feel that there are deep psychological structures that inform those given to belief in "conspiracy theories." Certain individuals hold deep such a deep mistrust for media or government, or power in general, that they "fill-in" hidden agendas--without regard to the extremely dubious sources for these theories. The "secret" for conspiracy theorists is generally that a cabal of liberals, conservatives, CIA operatives, bankers, corporate leaders, etc, are in fact collaborating for some nefarious, persecutorial end.

Of course, it is prudent to recognize that the truth can be easily "spun," and that goverment and media are both capable and culpable of lying. This country was founded on the distrust of consolidated power. Still, there is a difference in degree between a healthy scepticism and some of the outrageous beliefs in the market at the moment. Would you care to comment on the psychology of this kind of "extremist" thinking?

C. Nagy

Shankar Vedantam: we're running out of time, so let me just post some comments (about both stories.)

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Marquette, Mich.: Dear Shankar,

Do you think that simply being aware of this tendency to see bias or truth based upon our prior digested mindsets can lead us toward a more complex and comprehensive grasp of politcal conflict? Or, is this tendency so strong that a mere awareness of it will not help us transcend its power over our minds?

Michael Loukinen

Shankar Vedantam: good question. I think being aware helps, but my guess is these biases cannot be eliminated completely. In fact, I think we would do harm by eliminating them completely. Normal functioning involves emotions and feelings and pre-conceptions. To rip all that out may leave us bias free, but it may also leave us without some of the most precious things about being human ...

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Washington, D.C.: No, no! Humans aren't evolving! We were put here on earth as we are by God and that's it! We've always been the same and always will be the same! There's no such thing as evolution, and your "science" is just a bunch of fairy tales!

Ok, I'm kidding. But it is scary how many people believe just that...

Shankar Vedantam: more comments ...

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Boston, Mass.: I read a interesting book review, where the author theorized that evolutionary increases in human intellegence will grind to a halt because successful people have so few children. Do you think our societal pressures and the literal cost of raising children will wipe out many of these successful adaptions?

Shankar Vedantam: I have partially answered this above; I want to toss it into the mix ...

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Stanford, Calif.: What is new about your article? Most people who truly understand evolution know that it is about the survival of the luckiest (ie the ones who can live long enough to reproduce given the environment).

For example, take the obesity problem, back in WWII, we have famines all over, so people who can effectively store fats live on and reproduce. Now we have a completely different problem, fat people will now have a harder time to reproduce because they are looked down by the society, so gradually we will have more thin people. But obviously, this will be a slower process than war, so we will still see many fat people around for a while.

Shankar Vedantam: the less strong the selective pressure, the longer evolution will take. so yes, I would agree with you.

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Laurel, Md.: To date, evolution in both humans and other species has worked by the fact that the more suited an organism is to its environment, the more likely it will reproduce, and hence pass those traits on.

But today, we've accomplished two things:

1. Medicine in both humans and domestic animals have defeated many genetic characteristics making them uncorrelated with reprduction

2. We practice reproductive choice, which today means largely that advanced societies (the US, Japan and western Europe) don't replace themselves with reproduction

The offshoot of these two phenomena could be that we would de-evolutionize. It may take place more in the intellectual realm than the genetic, but it's hard to deny that advanced countries have to import people from less advanced ones due to fertility differences.

Shankar Vedantam: I think here again there is confusion between social norms of progress and evolutionary norms, but I want to post the comment ...

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Herndon, Va.: Mr. Vedantam: It's good to hear we're still evolving - maybe we'll actually have civilized human beings in the next few thousand years! In the meantime . . . do the scientists who study this area have any "guesses" as to what other "traits" human beings may be acquiring or losing?

Shankar Vedantam: so far the findings have been more about changes at the genetic level than in traits -- which are obviously several levels above the genes. One of the interesting things I didn't get to in the story, partly because I could not track down the lead scientist who was on vacation, was research into how malaria may be causing genetic changes as populations adapt. So as infectious diseases such as AIDS spread and kill large numbers of people, it seems likely you are going to see people who may have greater immunity gain selective advantage.

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Vienna, Va.: Mr Vedantam: Did you come across any information on how "awareness" developed from inanimate matter? Tom Hines

Shankar Vedantam: a very big question, and far beyond the scope of this story or this chat. How consciousness arose from the biology of the brain -- or if it is a different entity altogether --is the subject of several books, and much religious interest. I think it is fair to say most neuroscientists think of consciousness as having arisen from the biological brain, but it is also fair to say that as of now, the question of how subjective feeling can arise from the material world has not been resolved.

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Omaha, Neb.: I understand how evolution has worked up to this point, (i.e. survival of the fittest) but am confused as to its function in modern culture. For example, an ability to digest dairy may make certain populations more comfortable, but how does that give their progeny an edge over lactose-intolerant populations? In an age where reproduction is affected by both birth control and fertility treatments, and individuals with terminal genetic conditions can still have several children, how does evolution function?

Shankar Vedantam: As I mentioned sometime earlier, this was the sense I had before reporting the story. My error was in not realizing that environmental pressures need to have only small changes to have effects, because natural selection has multiple generations to work. Evolution is interested in people's survival long after they reproduce, since offspring need to be raised and that requires parents who are around for a long time. Then there are also more intangible advantages to having people live into old age? Who knows, the wisdom of age may help species like ours (with our peculiar propensity for self-destruction) survive ...

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Orlando, Fla.: I am a Christian and while I believe in evolution and natural selection, I wonder why after so much research are we unable to find any "missing link" humans. We have apes and we have humans, but what are some ideas as to why we can't seem to find the species in between?

washingtonpost.com: Eden and Evolution , Feb. 5, 2006

Shankar Vedantam: I wrote a Sunday magazine cover story that touches on this and several other concerns raised about evolution.

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Shankar Vedantam: That's all we have time for today. Thank you for chatting.

In connection with the bias story, I should mention that I am writing a weekly Monday feature on Page Two that attempts to explore ideas related to the news. Recent articles along this theme have focused on forgiveness (in the context of Ken Lay's death), and the link between money and happiness, following Warren Buffett's recent act of extraodinary generosity, and the changing nature of gifts in America, in light of Mother's Day.

Have a good week.

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