Thursday, February 01, 2007

Genetics of Heroes

Before I start my rant, I'd like to note that I enjoy watching Heroes. I'm a sucker for stories with seemingly ordinary-joe protagonists who have to both come to terms with their new abilities and are unexpectedly sucked into adventure and intrigue. I also think there should be more TV shows that feature sexy and intelligent geneticists. What annoys me about the show is the human genetics/evolution wrapper to the story.

First a bit of background. Chandra Suresh is arguably one of the most important characters in the series, even though he dies before the first episode. As a genetics professor in India, he studied people with extraordinary abilities and came up with a "crazy idea" to explain their origin. He published his hypothesis in a book called Activating Evolution. His obsession cost him his professorship, but he chose to move to New York and work as a cab driver to continue his research. He is killed as he is driving his taxi, and his son Mohinder, who also happens to be a geneticist, takes over his father's work. The first tie-in graphic novel, Monsters (pdf), tells the Suresh family's story.

When Mohinder comes to New York, he discovers his father had assembled a map showing where all the people with superpowers ("extraordinaries") live. The episode before last he explained to an FBI agent how it was assembled: the map shows individuals his father discovered have a "shared genetic marker" and they were "mapped and tracked by the human genome project". In the last episode, Mohinder gives a similar explanation to Nathan Petrelli: the people with special powers all "carry the same gene marker".

That's when I started shaking my fist at the screen (metaphorically) and exclaiming that the plot device makes no sense to me. Let me explain why.

1. All of the "extraordinaries" carry the same genetic marker with a different DNA sequence.
When the creators were asked about the "genetic marker", they confirmed that all of the people with superpowers carry a single unique stretch of DNA.
The show has mentioned a "genetic marker" several times. Is this something found in a person's DNA, is it a formula that takes into account other factors, or something else entirely?

As far as we know right now, there is an arrangement of start and stop codons that our people have that indicates their potential for having an ability. And so far everyone on the list seems to have that marker. But that may be just one piece of the puzzle.
First off, we need to figure out what is meant by a "genetic marker". In the simplest terms, a genetic marker is a segment of DNA whose inheritance can be tracked. Based on the what the creators have said, the superhero marker is a gene that encodes a protein, since it has a "start codon", which is a sequence of three bases that tells the protein-making machinery in the cell where code for the protein sequence begins, and a "stop codon" which tells the machinery where the code for the protein ends.

What we don't know is whether the gene is unique to the "extraodinaries" or if it's a variant of a gene even "normals" carry. However, in the last episode, Mohinder explains that Pete Petrelli can take on other's powers by "resequencing" of his DNA . So there is a common genetic marker, but the exact DNA sequence varies from individual to individual, and that DNA sequence is what gives our heroes supernatural powers. That suggests to me that the genetic marker is actually a new human gene, with a variety of alleles. The addition of new genes is a process termed horizontal gene transfer, and can be caused, for example, by the incorportation of genetic material from bacteria or viruses into humans (technical article: Belshaw et al. 2004) or by genetic engineering. I assume the series will eventually explain how this genetic marker appeared in unrelated people all over the world.

So what's my problem? I can suspend disbelief and accept that there is a gene that allows characters to defy the a law of physics - that's the premise of the story, after all. But it's harder to believe that there is a gene that gives people the ability to defy the laws of nature in different ways - one person can time travel, another can fly, another can heal any wound, and yet another can read minds. Young Micah appears to have inherited the gene, but his skill (controlling electronics) has nothing to do with the powers of his mother (split personality with superhuman strength) or his father (ability to pass through solid objects). If there is going to be a "scientific" explanation, why can't there be some logic to it?

2. The people who carry the genetic marker were found using the Human Genome Project.

When Mohinder claimed the Human Genome Project (HGP) was used to "map and track" the individuals carrying the unique "genetic marker", I think I actually cried out WTF!. The creators of the show apparently think everyone's DNA is freely available for analysis:

And when will we find out what factors are entered into the program that will generate a list like that? Did Mohinder's father have access to a huge DNA database?

Human Genome project. Genetic Migration databases. W.H.O. access points. These are all public databases for researches working in genetics.

Perhaps Heroes takes place in an alternative universe where the HGP actually has the genomic DNA sequence of every person in the world , but in the universe we live in that isn't even close to reality. The sequences released by the HGP are actually a composite of 24 different individuals, so analyzing that data alone wouldn't help you locate a genetic marker that is found in only a small number of people. Of course Chandra Suresh could have used data from the HGP as a starting point to map the superpower gene, but he would have had to collect samples and sequence the DNA from "extraordinaries" himself. Perhaps a maverick geneticist who is apparently a pariah at his university for his unorthodox scientific views would be able to convince strangers from all over the world that he should analyze their DNA, but I find it extremely unlikely.

OK, even if I buy the premise that a unique genetic marker that confers a variety of superpowers suddenly appears in people all over the world, and is discovered by a lone geneticist, it still leaves leaves the aspect of the Heroes "science" backstory that irritates me the most:

3. The superpower genetic marker has something to do with evolution.
This comment by producer/director Greg Beeman illustrates exactly what is wrong with Heroes' take on evolution:
What is your favorite part of the Heroes concept?

The exploration of human beings evolving 'of humanity going to the next level of evolution and the 'how, why, why now' questions that stirs up.
OK, here's the problem: there are no "levels" of evolution. Evolution has no direction. It's no wonder that Chandra Suresh's colleagues dismissed his ideas after he published the book Activating Evolution; his hypothesis that the superpower mutation has created an advanced "evolved human" demonstrates a serious lack of understanding of basic evolutionary biology.

That's not to say that humans have stopped evolving. Even now the human population is slowly changing. Here's the thing: unless the superheroes out-breed us "normals" (or kill us all off) their special genetic marker will never exist in more than a tiny fraction of the population.

I suspect our heroes are more likely an evolutionary dead end than the future of humanity. Nonetheless, I'll be watching when Monday rolls around.

For more on the similar topic, see the "Evolution and X-Men II" powerpoint presentation from "When Good Biology Goes Bad at the Movies.

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  1. Anonymous6:54 AM

    #2 had me shaking my head, as well. Even I knew that you can't use that database to run the kind of search program that Chandra devised. But I'm willing to allow some things to slip through the cracks for the sake of enjoying a fascinating show. It's just tough, sometimes, to suspend disbelief to the breaking point like that.

  2. Anonymous12:41 PM

    Loved this entry! I enjoy Heroes as well, but when they wrote in that those on "the list" were tracked through the HGP, I almost wet my pants.

  3. This comment has been removed by the author.

  4. Nice blog my friend. It is true, Heroes is a fascinating show, but in respect on science it is very bad. I wouldn't really mind, if the show wasn't talking about the genetic backround of the whole Heroes concept at all. But "bad" and so called "amateur" reference to biology and the Human Genome Project is too stupid and misleading. Most people don't know about science anything more than what they hear in TV and read in the newspapers and this is quite bad already (in my country at least). All my friends who watch the show are reproducing all that crap and it is really annoying. It's a pitty..
    I let it pass and watch the show, but only because the director's and actors' work is very good.
    Shows that use science in their backbone story should provide a scientific advising commitee to the scenario authors. Especialy a production of such an scale..

  5. #1 I don't see as being *that* big of a problem. It seems likely that the 'genetic marker', whether it's a new gene or a variant on an existing gene, is fairly similar in all the superpowered mutants, with only minor variations.

    The diversity in manifested powers could then be explained by saying that the mutation allows the development of special powers (psionics, reality alteration, whatever you want to call it), and their particular manifestation depends on the individual's phenotypic development, neural wiring, and even thoughts and emotions at the time of manifestation.

    This would be a better explanation of the variation than saying that there's a distinct version of the 'marker' for each and every power. It's also in tune with pseudoscientific explanations for powers in other media, such as the Wild Cards novels.

    Note that this also makes both Peter and Sylar make more sense. Rather than 'altering their DNA' with every new power acquired (at this point I guess we have to accept that both Mohinder and Hank are pretty dumb), they're actually rewiring their brains to include the capacity for more power manifestations or stunts, Peter through empathy and Sylar through intensive analysis of his victim's brains (and possibly digestion of their memory RNA - they haven't been too explicit about that part of the process).

    This accounts for how they can absorb multiple powers, and is just as good or better an explanation for why they both seem to be getting kind of unstable, since they're messing with their neural nets and neurotransmitter levels directly, as opposed to modifying the DNA in each of their cells.

    #2 is a bigger issue, but I tend to read it as the 'marker' itself being identified using data from the HGP, and the identification of any particular individual for inclusion on the list being dependent on the individual's DNA having been sampled, tested, and included in a database searchable by Chandra or Mohinder.

    Of course, we know that even when somebody's DNA is sampled, it's usually tested only for specific things and not completely sequenced, so that such a search would require ordering thousands or millions of new lab tests, and also that there's no unified, searchable database of this type in the world.

    There's also the point that even if the Heroes world is one in which complete DNA sequencing is routinely done and entered into a national or global database, the list can only turn up superpowered mutants who've had their DNA sampled at some point, likely leaving out billions of candidates. Actually, that's probably a good explanation why all the Heroes shown so far have come from industrialized nations - neither Mohinder nor Primatech has a means of reliably tracking mutants not in the database and not openly manifesting their abilities.

    As far as 'the next step in human evolution' goes, you're quite right that the language in the show betrays basic misconceptions about natural selection.

    On the other hand, even if the mutation for superpowers is very uncommon and has existed for some time, the possibility certainly exists for the mutant population to expand quickly *if* (and that's probably a big if) the mutation confers significant reproductive and survival advantages over those without powers, and if the mutation is either mostly dominant or they can find each other in sufficient numbers to produce breeding pairs.

    On the one hand, the survival chances of the empowered don't really seem all that great, given the depredations of Sylar and the upcoming 'Days of Future Past' storyline. On the other, many of the adult mutants shown so far do seem to have been successful in reproducing, and their offspring seem to be very likely to have powers as well (Nathan/Claire, DL and Nikki/Micah)...

  6. I'm going to talk about Superman and then bring it back around to Heroes.
    Superman is supposed to be nigh invulnerable because his tissues are super-dense compared to ours. This means he should be much heavier than us and flying should be right out.
    His Superboy clone was imperfect and couldn't fly or have super strength so the people in the lab gave him tactile telekinesis. That is he could levitate himself and anything he was touching.
    So the ability to fly could be a form of self-directed telekinesis.

    After seeing "Finding Nemo" I had another idea. Remember that scene where the fish escaped by all pushing the same direction? Well suppose our flying characters can influence the vibration of their molecules to so as a whole they give more of an upward push instead of all canceling each other out.

    Of course, all of this is all rubbish scientifically. You have to first accept telekinesis or at least the ability to unzip someone's skull from across the room.

  7. scott: I suppose the explanation that a single genotype could result in different phenotypes would work, with the common trait being the ability to circumvent the laws of physics. I also like the idea that Peter & Sylar's ability to absorb the powers of the others has to do with brain rewiring, with Sylar having to look at a brain to determine the wiring pattern and Peter doing it automatically.

    WRT #2, if I'm remembering correctly, there was dialog in one of the episodes (the one with superhearing mechanic) to the effect that the identified mutants had indeed all given DNA to the human genome project. It still seems really unlikely to me that so many people had had their DNA sequenced and that Mohinder's father had access to all that data. I guess it's not so hard to believe along with the superpowers.

    I do think it's interesting that so many of the characters turn out to be blood relations. It's still fuzzy as to the source of this particular mutation (or new gene?)- the most recent episode suggests that new "mutants" are popping up five years in the future. I'm wondering if we are seeing large-scale genetic engineering at work here.

  8. ibid: I think it's fun to speculate on how the various powers might work. I'm not sure how the "push" you're describing would make someone fly - I don't think it's molecular vibration that keeps us on the ground, but gravity. Or perhaps that would alter the local curvature of space-time effectively generating anti-gravity?

  9. Anonymous2:44 PM

    go outside

  10. I am outside - thanks to our fabu wireless network :-)

  11. LOL Peggy

    The first season of Heroes is over and some of the mysterious genetic backround is explained..
    Indeed the "super hearing" lady had given blood for some tests years ago.
    Possibly this is how she was tracked down..
    If not all people on earth give blood samples, someone could not produce by bioinfortmatics the complete list of the "extraordinary"...
    His list would though represent the portion of the "extraordinary" in respect to the sample, thus giving him an estimate on how many "heroes" really exist in the whole world..
    I would like to point out also that as it seems, that what we are watching is a sertain generation of heroes.. There where heroes before them and they faced similar complicated situations. When a group of people gets super powers (speaking in general, politicians involved), the way each one of them uses these powers is clearly different. These people then cluster in smaller groups with common goals each group supporting and promoting its purpose.
    I believe the second season will give some information about the past heroes generations, we should just wait and see...

  12. xecoli: I think you're right, season 2 should reveal more of the mystery of their origins. In the meantime I should do an updated post that mentions all the newly revealed info.

  13. Wow. This is the coolest blog ever!

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  16. Anonymous3:08 PM

    i just think that we need to get past the part where we're thinking too much about shows. i realize there are some issues, but i think we should, as you said, "let stuff through the cracks"

  17. I have only watched this show in school for a project and I think that this blog that you, Peggy (which is my moms name) created is really good at explaining the faults of the show to those who are confused about it or have not even seen the whole season (like me). But now that I do have this greater under standing of Heroes and the unrealisticness (If that is a word) of its 'factual' content. I agree with those who said that it should not be that important and that it is a really cool show and that is all that matters. I do understand that you are not saying that this makes it a bad show . But I just wanted to get my point across as clearly as I possibly can.

  18. Anon and last time I checked: I get what you are saying, and I agree that it's a cool show. Personally, I would enjoy it even more if there was some reality to the science, but bad science doesn't in and of itself ruin a program for me. I do think it's a good starting point for discussion of genetics and other biology.

  19. Anonymous9:35 AM

    I like this entry, and even though a lot of the stuff that they show in heros can't be true, its a fun show and i believe that the director and actors did a very good job. I agree with jim, and xecoli. This show is awesome, but like jim said its tough to suspend disbelief. Keep writing Peggy!

  20. Weirdo who LOVES Hiro9:44 PM

    Of course its not the same universe, do we have "hereos" in our universe? Also, when u say that evolution has no direction, are you trying to say that only one single organism created an entire species....NO FREEKIN WAY!!! multiple organisms each evolve in an exactly similar way.....thus creatting a species, thats how there can be heroes who all share a similar trait (special and weird powers)

  21. There is also a possibility that the expression of the powered gene is based on epigenetics, which would account for manifestations at different ages and different powers in children of powered individuals. Peter's retention of methyl groups (epigenetic tags) may account for his ability to 'remember' certain powers, and why he loses his retained powers due to the (also questionable) eclipse because the epigenetic tags his powers allowed him to retain are scrambled. While I acknowledge that some of the presented powers are indeed biochemically and physiologically unexplainable, I am saying that the unique expression of the code (which may be thousands of bases for all we know) can be traced to the gene regulation (pre- and post-transcriptional) which inherently creates infinite possible combinations and infinite possible phenotypic manifestations.


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