Wednesday, April 15, 2009

The Next Phase of Human Evolution?

Back in February 2003 bioethicist Gregory Stock gave a TED talk where he speculates that biotechnology - particularly genetic engineering and individually tailored personalized medicine - will ultimately "drive" our evolution:

He thinks the human genome project was the first step in revolutionizing medicine, unravel the aging process, allow us to modulate our emotions, and generally improve human life. He thinks human cloning - "birth of a delayed identical twin" - will happen in 5 or 10 years, and be "no big deal". All of that seems pretty straightforward.*

Anyway, he then goes on to what I would consider the very speculative part of his thesis: embryo selection and genetic engineering that will drive human evolution. He talks about selecting embryos that don't have the risk of manic depression, and screening for a desired personalities, which ignore the role of the environment, in addition to our genes.

Even more speculatively, he thinks that the technological solution to introducing genetic changes in our offspring will be the development of an extra artificial chromosome that can be used "program" parents' genetic preferences in their offspring. It's not clear to me how that would work exactly - adding new genes won't necessarily override the genetic program that's already present. If both parents are brown-eyed, it's unlikely that simply adding new DNA sequences will override the genetic code in their offspring that drives the synthesis of brown eye pigment. The problem becomes even more difficult when a trait is affected by many genes.

And it's not clear to me how genetic modification, which he notes will likely be reserved for the wealthy, will drive human evolution in any meaningful way if the majority of humans don't have access to the technology. How will such changes spread in the population when parents with different numbers of chromosomes often produce infertile offspring? Perh

Of course I'm not the only one who has pointed out such issues. The review Stock's 2002 book on the subject, Redesigning Humans: Our Inevitable Genetic Future (amazon.com, indiebound.com), in Science makes it sound like he has taken some of those issues into account, so I'm not sure how he envisions genetic engineering carried out by a tiny segment of the population significantly affecting human evolution. I suppose I should read his book.

It's worth nothing the pace of biotechnological development is very difficult to predict. Back in 1998, Stock claimed that human germline engineering "will be a realistic option within a decade or so." Here we are, more than a decade later, and I don't see human germline engineering becoming an option in the immediate future, both for technical and ethical reasons.

* Except for the "no big deal" part - some people still think hormonal birth control is a big evil deal, and that's been around for nearly 50 years. In vitro fertilization also has loud detractors. I doubt the people who are against control of human reproduction today will quickly jump on the cloning bandwagon. He does note that some people will be against human genetic engineering for religious, ethical or other reasons. I suppose the question is whether those people will have a significant effect on the adoption of the technology.

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4 comments:

Anonymous said...

In the blink of an eye cosmic-time wise, we are going to be able to change ourselves into just about anything we want.

Appearance, gender, and race are going to take on whole new meanings.

Don't kid yourself if you think people aren't going to be standing in long lines and pay whatever is necessary to become what they think is different and better than what nature gave them blindly.

Just look at all the ads for weight loss and anti-aging creams if you think I am mistaken. And those are low-tech.

Science fiction has barely scratched what we are going to become - and what those who succeed us will be and do.

graywave said...

Yeah, heard this before. The fact is that it is the environment that drives evolution. We can tinker with the human genome or radically change it - like we messed about with dogs and other domestic animals through selective breeding - and for a while it will seem as if we're actually shaping our destiny. Then the climate will change, or a new predator will emerge (like a virus, say) and Nature will pick who survives and who gets to breed and who doesn't.

As long as we dominate our environment we can control what we become - somewhat - but we won't be controlling it forever, or even for very much longer the way things are going.

JHSteinberg said...

You write here often enough to make it clear that you know about biology - enough, certainly, to understand that evolution occurs over geologic time frames.

Given the understanding that "natural" evolution occurs over geologic time, do you really think that the ability to create custom genotypes *within a single generation* isn't going to accrue over geologic time to play the single most important role in genetic change? It's easily going to overwhelm genetic drift, selection, and every other natural mechanism of evolution (if one cares to tease them apart; obviously all of these things would act in concert and in response to one another).

Even if only the world's richest 1% of the population engages in this, if they do so every generation combined with propagation of their offspring's genetics, I think it's self-evident how this would drive evolution over the millenia.

graywave said...

It's quite possible that messing about with our genes will produce changes that will survive over long periods. We can even make very widespread changes and make them persist for as long as we have a society capable of doing so. But only changes that offer a reproductive benefit will spread naturally and widely in the human population.

Cosmetic changes, changes to lengevity, changes to intelligence, improved disease resistance, and so on may have little or no long term benefit to the species and will eventually disappear. Some, like longevity, may actually be detrimental or may be quickly out-competed by shorter-lived but faster-breeding varieties.

It may well be that changes will persist, certainly in the short term we can expect some interesting variants, but I think the hype about how this will 'change the course of human evolution' is overblown.

When people act as the primary force for selection, you can drive rapid change. Look at domestic dogs. When that period is over (as it will be one day) the environment takes over again. The Australian wild dog, the dingo, was moved a long way from its original wolf ancestors by human breeders and then left to nature's care again. Perhaps we all have a dingo future ahead of us instead of a wolf future.