Sunday, April 10, 2011

Pretty politics

My Canadian readers are no doubt preparing for the upcoming federal election. Living in a democracy, we have the opportunity to vote for the candidate we think is most competent (even if sometimes it seems like all options are pretty grim). If we choose well, we may be rewarded: there is much evidence that intelligence and competence correlate with effective performance in politics. Unfortunately, research also shows that intelligence can’t be predicted from one’s appearance. Everyone knows that. That’s why we would never choose a competent candidate solely based on what they look like. Or would we?

To evaluate how much looks factor in when choosing a political candidate, Swiss researchers asked over 600 adults to rate which of two faces (in photographs) looked most competent. Little did the participants know, the two faces were actually of two candidates in a past French parliamentary election. As it turns out, over 70% of the participants ended up picking the candidate who had won the election.

To take things a little further, the researchers then carried out a similar experiment in children. They had over 600 children ranging from five to thirteen years old play a computer game that involved a sailing trip from Troy to Ithaca (sounds familiar?). After the game, the children were shown the same two faces used in the adult experiment and were asked to choose who they would prefer to have as captain of the boat. Again, just over 70% of the children chose the election winner.

Interpreting these results can be a bit tricky, but keep in mind that we already know that competent people aren’t necessarily prettier. One thing is clear: the experiments tell us that adult and children use similar types of visual information when judging whether someone is competent or not. The researchers also conclude that voters don’t factor in enough information about the actual performance of candidates when heading to the ballots, relying instead on what candidates look like. While I’m sure they are at least partially right, I think it’s a bit of a stretch to come to this conclusion given the simplicity of the study.

In any case, the results serve as a good reminder to think about our candidates and to take our civic duties seriously. After all, we wouldn’t judge a book by its cover…

Reference: Predicting elections: child’s play! (2009) Antonakis J and Dalgas O. Science 323(27):1183.

Monday, April 4, 2011

But what about clones?

I feel cheated.

When I heard all the buzz about a recent Canadian study showing that identical twins don’t share the same DNA, I thought: there’s this week’s blog post. Easy peasy. I imagined the title of the article was probably something like “Identical twins don’t share the same DNA” or, even better: “Just kidding: everybody is unique after all”. Instead, to give you the low-down on this moderately exciting finding, I had to read through a paper called “Ontogenetic de novo copy number variations (CNVs) as a source of genetic individuality: studies on two families with MZD twins for schizophrenia”. So don’t ever say that I don’t love you.

The finding is very straightforward and fairly intriguing, but before I dish out the details, I have to remind you about two concepts you may not have heard since high school (but rejoice: it's sex-related): meiosis and mitosis. Meiosis is what happens when one cell with two copies of each chromosome divides to produce gametes – in our case, sperm cells and egg cells, each with a single copy of chromosomes. This process is necessary for sexual reproduction. Mitosis is what happens when one cell generates two separate sets of chromosomes and then divides, leaving each daughter cell identical to the mother cell. This process is necessary during early development.

Now onto the article: the researchers were on the hunt for genes that are involved in schizophrenia, and as is often the case in these types of studies, they were looking at identical twins. The idea is that diseases can arise from genes (for example, Huntington’s disease), from the environment (for example, certain forms of cancer), or from a combination of both (for example, certain forms of Alzheimer’s disease). If identical twins have the same genes but only one of them gets a disease (say, schizophrenia), then researchers typically rule out genetics as the cause and examine what differences in the environment of the two twins may have caused the disease. See how that works?

In this study, the researchers were particularly interested in a DNA alteration called “copy number variations”. You see, DNA is never perfect, and sometimes cells have abnormal copies of big chunks of your DNA. These copy number variations can be harmless, but they can also cause certain diseases, so geneticists are paying close attention to them. In any case, the researchers found that supposedly identical twins had different sets of copy number variations when compared with their parents (meaning they didn’t inherit these DNA alterations from their parents). The cool thing about this finding is that the researchers can now determine when the alteration happened depending on who has the different copy number variation. If both twins have the same copy number variation, then we know it originated during meiosis (when the parents were generating eggs and sperm). If only one twin has the variation, then we know it originated during mitosis (during development).

While the article doesn’t focus all that much on the fact that identical twins have the same DNA (I hate to say it, but we kind of already knew that), this tidbit of information is relevant in two ways. First, it’s going to change how researchers carry out twin studies, because we can no longer assume that identical twins have the same DNA (as if we needed to complicate things further…). Second, this finding might lead to a new way of thinking about genetic diseases.

So there you have it: we are all unique individuals after all. Up next: your parents aren’t who you think they are. Your “parents” are really bug-eyed aliens from Neptune! (as always, bonus points for the correct reference in the comments…)

Reference: Ontogenetic de novo copy number variations (CNVs) as a source of genetic individuality: studies on two families with MZD twins for schizophrenia. (2011) Maiti S et al. PLoS ONE, 6(3):1-13.

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