If I could just find a red pill…

I just read an article in the San Francisco Chronicle about the recent completion of a project to sequence the genome of Canis Familiaris, a.k.a. the dog. And once again the article talks the genes and how great it’s going to be to find the genes that cause certain traits.

I really need to start reading Nature and biology journals to find out if researchers are really trying to find “the gene” that causes x or y trait, or if that language has just been dumbed down for mass consumption. Trying to find a single gene which causes a complex trait or behavior is like trying to find the bee that causes a swarm or the nerve that causes sight.

Genes encode nucleic acids, and it is in the interaction of nucleic acids and proteins that most of the complexity of genetic expression arises. It’s timing and environment that we need to be studying, not the gene sequence. The gene sequence is very handy to have, but it’s just a rough guide. The article mentions that dogs and humans have almost the same genetic compliment. Duh. I could have told you that. Yams have more chromosomes than human beings do, but that doesn’t make them more complex organism. Although maybe they’re just snuggled down in the dirt thinking deep yam thoughts. Who knows.

I remember a segment of Bill Bryson’s book A Short History of Nearly Everything (at least I think that’s where it was) which described the practice in the scientific community of designating a particular skeleton as being the canonical reference for an entire species. That’s handy, but it would be a mistake to say that a particular skeleton is what all skeletons of a species should look like. Take any two humans and you might find a different number of bones in the hands and feet. In the same way, no two individuals in the same species have the same genes or even the same number of genes. With the possible exception of identical twins, and I bet even they have different non-coding DNA.

So it comes as no great surprise that dogs and humans are very close in the composition of their genomes. We’ve both got hair, similar muscles, bones, skin, connective tissues, saliva, blood, and a bunch of other stuff I won’t go into because I haven’t had breakfast yet.

I suspect that if you really want to get in to the complexity of mammalian life, you should spend more time looking at the placenta and less time looking at the genes. It would be really interesting to create an artificial matrix capable of taking a zygote to maturity. I may be wrong here, but I’m pretty sure that all animals develop to a state of independent maturity inside a matrix of some sort, be it an egg or a womb*. That means that the environment that the single cell develops inside of is an aspect of the species. What happens if you remove it to another environment that allows the zygote to develop into an embryo, but isn’t constructed with the species’ genes?

*Not sure about clams and sponges. I’ll have to look that up.

No Responses to “If I could just find a red pill…”

  1. Suzy Says:

    I remember seeing a drawing in one of my Dad’s veterinary books (he was a country vet who also worked on tigers, giraffes, chimps, etc!) of mammalian embryos (es?): about 12 or so. They looked exactly alike! I thought that was really neat. Does that mean with a slight alteration in environment, I could have been a beagle?

  2. Nealie Says:

    Yeah, I was thinking the same thing as Suzy there. Are you saying that we are like the Aliens in the Sigourney Sci-fi films? That the fetal environment has as much to do with the way we turn out as the genetics? If so, that would dramatically alter the import of using a surrogate mother to bear your child.
    I guess, in terms of the person you turn out to be, I agree with the envirnoment’s affects on development. It’s the concept of environment affecting the genetic development that seems a little confusing to me.

  3. Administrator Says:

    The ideas in my head were kind of half-formed when I wrote this post. One thing that really informed my ideas, but which I did not mention, is the placental womb that most mammals have.

    There’s basically three types of mammals: placental, marsupial, and oviparous. All have to do with the gestation of the embryo. Oviparous mammals like the platypus and echinda lay eggs with the embryo inside them, just like reptiles and birds. The embryo develops in a completely self-contained unit. I’m not completely clear on how marsupials work – I know that the young are born in a very under-developed state, and then they are moved to the mother’s pouch to continue developing. It’s really weird, and I don’t know much about it.

    Most mammals are placental. The placenta surrounds them and is connected directly to the mother’s uterus. The developing embryo receives nourishment and processes waste using the mother’s circulatory system. That’s got to have a huge impact on the path of development.

    Consider foetal alchohol syndrome, or the birth defects caused by Thalidomide. Both of those problems are unique to placental mammals (although marsupials might be susceptible, now that I think of it.) These both create a massive – but non-genetic – impact on the developing foetus.

    But no, I don’t think you could cause a human embryo to develop into a beagle. A Golden Retriever maybe. 😉

    I need to start reading up on developmental biology and gene expression to really develop this train of thought.

    Honi soit qui mal y pense.

  4. Suzy Says:

    “That’s go to have a huge impact on the path of development.” Consider what the mother goes through as that “path!” Some of us do much better than others. Something no male, no matter how supportive, can ever imagine. Of course the flip side is: it is an AWESOME experience!

  5. spoonix Says:

    While it’s certainly true that the environment can influence the development of the fetus, that doesn’t mean that understanding and possibly being able to manipulate the chemistry behind genes and how they work their magic is a bad thing.

    It’s not a silver bullet, but it’s not useless, either. The fact that certain people seem to be at higher risk for cancer, heart defects, mental illnesses, or whatever because their parents and/or grandparents developed implies that the root of the problem is in genes and how they affect the chemistry of cells. Much like unraveling code written by a lame C programmer, the first step in understanding the system is to map out the functions and figure out which part does what. Knowledge here could lead to insight on the mechanism behind other diseases, and that could in turn lead to treatments and possibly cures later on down the road.

    But it’s the part where this could also be used as the basis for eugenics that makes my skin crawl.

  6. Administrator Says:

    You’re right, comprehenisve knowledge of genetics is absolutely necessary if we want to start tackling hereditary illnesses; my point is that it won’t be sufficient. The science of genetic expression really needs to be developed (and, as it turns out, it is getting a whole lot of attention these days).

    One of the sources of my frustration is that my mother and I had basically the same introduction to genetics, and we were in college twenty years apart. We did experiments where you’d extract bacterial DNA, add an enzyme to it, and then spin down the genetic material in a centrifuge and sort it out to see how the DNA bits had been cut up. And that was about as sophisticated as it got. It was about the CS equivalent of getting a Hello World program to compile.

    There’s a lot more to know.

    As for eugenics . . . can’t have knowledge without the potential for its abuse. Look at it this way; we might yet realize Jon Stewart’s dream of a hockey team composed entirely of Olsen twins.