Terry Grossman: Rethinking the Promise of Genetics
Great article from h+ magazine from about a week ago: "Rethinking the Promise of Genomics". This is by Terry Grossman, co-author (with Ray Kurzweil) of Fantastic Voyage:
I used to be a big believer in the enormous potential of genomics, and each of my two previous books, Fantastic Voyage and TRANSCEND: Nine Steps to Living Well Forever, had chapters devoted to this topic. The relevant chapter in the earlier book, Fantastic Voyage, published in 2004, was titled “The Promise of Genomics.†My co-author in these books, Ray Kurzweil, is widely regarded as one of the world’s foremost inventors and futurists, and he has made predictions for what is likely to occur in the future in the field of genomics . Yet, these days I find that I am feeling far less confident at least for the near term about the near term prospects for this “promise.â€
Here's a key quote by Grossman:
Currently I have moved much closer to the idea of “genetic irrelevance,†the idea that in the overwhelming majority of cases, our genes are of much less importance in determining our fate and that the environment in which we live and the lifestyle choices we make are of far greater importance.
Please note that I said this is true in the “overwhelming majority of cases,†but it is not true all the time. About one in 20 people is born with an abnormal gene that will create a major problem that can affect life and be quite relevant, either from birth or at some point further down the line. Examples include cystic fibrosis, a genetic disease that can manifest from birth for which we have been doing routine screening for decades and the BRCA-1 and BRCA-2 genes, which dramatically increase a woman's risk of breast and ovarian cancer later in life. But for nearly 95 percent of us, we come off of the assembly line of birth virtually perfect.
Illuminating stuff. Go exercise! It's important that the advocates of science and technology make it clear to the public that we are willing to be pessimistic about a technology's dividends when it looks rational to do so. Grossman's article reminds me of an excellent 2001 article by John Smart, "Performance Limitations on Natural and Engineered Biological Systems":
The more complex any life form becomes, the more it becomes a legacy/path dependent system, with many antagonistic pleiotropies (negative effects in other places and functions in the organism) whenever any further change is contemplated. It seems that evolutionary development, just like differentiation from a zygote or stem cell to a mature tissue, becomes increasingly terminally differentiated the more complex and specialized the organism. One extreme case of this kind of terminal differentiation, at the cellular level, is nerve cells in the human brain, which are so specialized, and the connections they support so complex, that they cannot even replace themselves, in general. Could they eventually learn to do so without disrupting the connectionist complexity that they create in the brain, after their development has stopped? Perhaps not. The more compex the system becomes, the less flexible it is. It gets progressively harder to make small changes in the genes that would improve system, and given how finely tuned so many system elements are, large changes are out of the question.
Because the reasons outlined by Grossman and Smart, I am more in the school that cybernetics (implants, brain-computer interfaces, wearable computing, etc.) will provide the most significant performance upgrades to humans in the nearer term (20-30 years). At first bio-transhumanism will be more of a side phenomenon than the central thrust of the transition. There will be much more effective and reliable means to make humans stronger and faster before we can make ourselves live longer and deeply exploit our own genetics.
Open Science Summit: Berkeley, July 29-31
The Open Science Summit is being held at Berkeley on July 29-31. Here's the description:
This summer, scientists, hackers, students, patients, and activists will convene to discuss the future of our science/technology paradigm. Topics include: Synthetic Biology, Gene Patents, Open Data, Open Access, Microfinance for Science, DIY science, DIY Biology, Alternative Funding for Science, Open Source Drugs, Patent Pools, Open Health/Medicine, Patient Advocacy for Innovation
Ready for a rapid, radical reboot of the global innovation system for a truly free and open 21st century knowledge economy? Join us at the first Open Science Summit, an attempt to gather all stakeholders who want to liberate our scientific and technological commons to enable an new era of decentralized, distributed innovation to solve humanity's greatest challenges.
For more information, read their about page. Early registration, which ends June 1st, is just $60. After that it's $100.
New Book Examines the Flawed Human Body
From the Genetic Archaeology blog:
Humanity's physical design flaws have long been apparent - we have a blind spot in our vision, for instance, and insufficient room for wisdom teeth - but do the imperfections extend to the genetic level?
In his new book, Inside the Human Genome, John Avise examines why - from the perspectives of biochemistry and molecular genetics - flaws exist in the biological world. He explores the many deficiencies of human DNA while recapping recent findings about the human genome.
Distinguished Professor of ecology & evolutionary biology at UC Irvine, Avise also makes the case that overwhelming scientific evidence of genomic defects provides a compelling counterargument to intelligent design.
Here, Avise discusses human imperfection, the importance of understanding our flaws, and why he believes theologians should embrace evolutionary science.
Our brains and bodies are both full of flaws. According to the pre-transhumanist worldview, the plan is just to sit around for the rest of eternity with these flaws, even as we colonize the Galaxy. According to the transhumanist worldview, the plan is to analyze these flaws, debate whether they are flaws or not, and consider fixing them if it seems practical and desirable. The latter makes sense, the former doesn't.
The New Scientist CultureLab blog has more info on the book.
Risk From Engineered Microorganisms, Strategies for Evolutionary Dominance
From yesterday's list of links, I particularly want to call attention to the rotifer link. This press release is interesting because it shows how animals can survive even when they are exact genetic copies of one another. Instead of outcompeting parasites through mutation, they run away by going into cryptobiosis. I predict that a form of asexual multicellular synthetic life will be created by 2030 that can defend against parasites through aggressive defense, say silica spines, so that running away isn't even necessary. These organisms will just sit around and reproduce. The primary method to get rid of them at first will be dessication, but this will eventually prove useless as they disperse too widely to target.
What many humans don't realize is that we are surrounded by quintillions of organisms with very little genetic diversity that dominate us in terms of biomass and persistence. They are the status quo -- we are the aberration. These are organisms that have survived every mass extinction. Culprits include the tardigrades (which can survive outer space), nematodes (absolutely ubiquitous; it is estimated there are between 1018 (one quintillion) and 1021 (one sextillion) nematodes worldwide, and they are crawling all over you right now), chaetognaths (considered useful models of basal bilaterans, there are a lot of them in the oceans, really a lot), and so on.
The only reason that these organisms aren't ripping us all to shreds right now is because there have been no synthetic biologists to push them out of evolutionary minima and give them more sensible strategies for total domination. Sorry to be alarmist, but I studied evolutionary biology for a couple years and that is my opinion. Evolution is terribly poor at transversing local minima to reach a global optima, and that is really the only saving grace for fragile macroscale multicellular agglomerations like ourselves. Interesting and low-energy-cost evolutionary innovations are rarely combined because they require several working parts to come together which are maladaptive individually but adaptive in cooperation.
The reason why rotifers are interesting is that their lack of genetic diversity makes them a good model for self-replicating machines. The ability to switch into a dormant, armored state (cryptobiosis) seems characteristic of a variety of small organisms, and we can expect this ability to be exploited to the fullest by human-engineered microscale replicators. The ability to distribute many of these replicators across a wide area will eventually create a "viral load" scenario analogous to the one faced by aging humans -- so many diverse beings build up in our body that the workload faced the immune system to combat nascent infections eventually becomes prohibitive and the system breaks down.
Some scientists have laughed at the idea that human-engineered organisms could dominate microbes that have evolved for billions of years, but I find this ridiculous. Human-engineered artifacts have already outperformed everything created by evolution in terms of energy density, speed, mass, acceleration, local dominance, and so on. The key point is that evolution is radically dumb (but it has many trials available) and humans are very smart. Let's discuss some of the ways to engineer microorganisms that cannot be defeated by the legacy biota.
1. Broad-spectrum biocides: natural organisms use a variety of biocides, but observe that humans have created thousands of highly effective synthetic antibiotics and biocides that evolution never discovered even after four billion years of experimentation.
2. Phage-immune bacteria, for instance bacteria that use genetic programs incompatible with malicious code injection by phages. Phages are the main bacteria-curtailing force on the planet and we depend on them for our survival.
3. Bacteria specifically engineered for immunity to broad-spectrum antibiotics which produce and secrete these antibiotics as a biofilm. There is even the possibility of release-and-shield, where microbes release the biocide then shield themselves from it for long enough for the competitors to be defeated, at which point the shield is raised.
4. Sucking them in: microorganisms could coat themselves in a gel shield which absorbs and dissolves both nutrients, phages, and rival microbes. For instance, the extracellular matrix of animal tissues is much stronger than the slime layer used by bacteria. Cooperative colonial bacteria could create stronger extracellular shields depending on how well-established the colonial region is, devoting stronger shields to the colonial center and weaker shields to the exploratory fringes.
5. Incubation-then-release: many evolutionary minima involve colonial organisms that are evolutionarily strong in larger colonies but evolutionarily weak in small colonies. By sterilizing a large area, filling it with nutrients, and allowing a founder population to develop (a "mega petri dish"), an important evolutionary minima could be hopped.
6. Quorum computing: evolution has developed a variety of means for microbes to communicate with one another on a crude level: quorum sensing. One of the interesting evolutionary innovations of the last billion years was to produce multicellular organisms that survive against many uncooperative microbes. By creating microbial superorganisms that effectively cooperate and compute using biocomputation, it may be possible to beat multicellular life at its own game by creating "organisms" miles across that effectively cooperate to defeat all rivals. This is definitely not a near-term risk but it could be a risk within the lifetimes of many alive today, given no singleton that guards us at a low level.
7. The last point in particular opens up a very large space for experimentation. For a colony that knows how to differentiate its perimeter members from interior members, it can activate all sorts of interesting genes in the perimeter members to make life miserable for organisms next to them. Bacteria already do this in a rudimentary way with quorum sensing. As long as a suitable barrier can be erected, the production of a variety of poisons is possible and safe for the majority of the colony.
Even natural selection in hospitals is enough to create killer bacteria immune to many antibiotics. What about bacteria specifically engineered by smart humans for reproduction and survival?
Live Webcast in Ethical Issues in Synthetic Biology
There's an interesting live webcast on synthetic biology happening tomorrow at 12:30PM, sadly I can't make it, let us know how it went if you do tune in.
PGD-IVF Would Lead to Designer Babies
George Dvorsky at Sentient Developments points us to an op-ed at New Scientist titled "Fears over 'designer' babies leave children suffering". The author writes:
Such fears are misplaced: IVF-PGD is little use for creating designer babies. You cannot select for traits the parents don't have, and the scope for choosing specific traits is very limited. What IVF-PGD is good for is ensuring children do not end up with disastrous genetic disorders.
I, along with dozens of prominent scientists in the field, disagree -- IVF-PGD would be useful for creating designer babies. Would would would. To boost this position, the author links another New Scientist article... (one that he probably edited, being biology features editor) which seems to contradict him:
Part of the problem is that only one or two cells are available for screening. Until recently this greatly restricted the tests that could be done. However, new ways of amplifying DNA are making it possible to do hundreds of tests. That means clinics will be able to screen for a much wider range of harmful mutations - and for desirable variants too.
Only one paragraph that I can find appears to support the op-ed author's idea that IVF-PGD couldn't be used for designer babies:
How much further can selection go? What of that object of tabloid hysteria, the "designer baby"? Will we one day be able to ask for a tall, musical, blue-eyed boy or a dark-haired girl? Even if regulatory authorities allow us to use PGD to select desirable gene variants, there are major snags. For starters, IVF typically generates fewer than 10 embryos per cycle. This means parental choice will be very limited. "I don't think anyone in their right mind would ever go through IVF to select the hair colour of their offspring," says Yuri Verlinsky of the Reproductive Genetics Institute, Chicago, one of the pioneers of PGD.
This Verlinsky quote is really confusing. Elsewhere, Verlinsky has been quoted as saying that PGD-IVF could lead to a "disease-free society" (a sloppy way of saying a "genetic disease free society"), but he claims that people won't use it to choose the hair color of their offspring. His quote doesn't make it clear whether he's talking about his opinion or the technical challenge. Also, the author of that (non op-ed) piece seriously breaks journalistic neutrality by calling designer babies an "object of tabloid hysteria" when many prominent scientists in IVF take the idea seriously. It's like the contributors at New Scientist are on misguided vigilante missions to make emerging technologies sound more palatable to the mainstream.
In any case, the limitation on the number of blastocysts can be circumvented using multi-generational in vitro embryo selection, which Verlinsky should have already considered, and if he hasn't, he has tunnel vision. So he either 1) is scientifically uncreative in his own field, or 2) knows that more advanced PGD-IVF could be used for designer babies, and just wants to keep it a secret from the public because he wants to get them to accept the technology incrementally, like boiling a crab in water that increases in temperature only slowly.
In general, I think the op-ed is a shoddy example of memetic engineering -- the author is trying to distract attention away from the designer baby controversy to help promote PGD-IVF for eliminating genetic diseases. Good motive, but somewhat dishonest, because I doubt that even the author believes that PGD-IVF would be useless for designer babies.
Speaking of "designer babies", I hate the term. As James Hughes said in WIRED, "the term "designer babies" is an insult to parents, because it basically says parents don't have their kids' best interests at heart". How about just "PGD-IVF babies", a non-catchy term, because it shouldn't become catchy and be used to discriminate against children born using the tech or parents who decide to use it? This would be in the same vein of Aubrey calling his project "Strategies for Engineered Negligible Senescence" to make it deliberately difficult to misunderstand. The project of SIAI could become, "the Engineering of a Human-Values Reflective Optimizing Process".
Also, we must remember that New Scientist lacks credibility. Instead of reading New Scientist, how about PhysOrg and Eurekalert? Or Next Big Future?
Either way, the whole issue matters not, because designer babies are largely irrelevant and will be eclipsed by things like strongly self-improving superintelligence and molecular manufacturing. See "Evolution by Choice" by Mitchell Howe.
Cellular engineers make multicellular tissues from the bottom up
Via Eurekalert:
BERKELEY, CA – Scientists at the U.S. Department of Energy's Lawrence Berkeley National Laboratory can now control how cells connect with one another in vitro and assemble themselves into three-dimensional, multicellular microtissues. The researchers demonstrated their method by constructing a tailor-made artificial cell-signaling system, analogous to natural cell systems that communicate via growth factors.
Artificial tissues are presently used in medicine for a range of applications such as skin grafts, bone marrow transplants, or blood substitutes, as well as in basic medical and biological research. Tissue engineers try to improve upon or repair natural tissues by manipulating living cells from one or more donors, sometimes in combination with synthetic materials. Unfortunately, in this "top down" approach, the cells assemble themselves randomly, losing the 3-D organization that is key to many tissue functions.
"Our method allows the assembly of multicellular structures from the 'bottom up,'" says Carolyn Bertozzi, principal investigator in the research, who directs DOE's Molecular Foundry nanoscience research facility at Berkeley Lab and is a member of the Lab's Materials Sciences and Physical Biosciences Divisions. "In other words, we can control the neighbors of each individual cell in a mixed population. By this method, it may be possible to assemble tissues with more sophisticated properties."
Bottom-up cellular manufacturing -- available now! Next -- molecular manufacturing using specialized organelles that extrude inorganic materials. Superlative futures, here we come!
Anthropobiota: Tree of Synthetic Life
A proposed name for the new kingdom of synthetic life: Anthropobiota.
(This is hardly original... see Anthropocene, but it seems most likely to catch on.)
The first member of Anthropobiota will likely be Mycoplasma laboratorium, at the J. Craig Venter Institute. The group also "hopes to eventually synthesize bacteria to manufacture hydrogen and biofuels, and also to absorb carbon dioxide and other greenhouse gases", according to the Wikipedia page. This would lead to additional species for specific purposes. The point of Mycoplasma laboratorium is to implement a "minimal bacterial genome", a jumping-off point for future synthetic species. All of these species would fall under Anthropobiota, as long as the genetic material is entirely synthetic. If not, that's just genetic engineering.
Anthropobiota would be located outside the root of the Tree of Life. It would be a complementary Tree, at first much smaller than the original. The Tree of Life contains between 10 million and 1 billion bacteria species, between 10 and 30 million animal species, and some unknown quantity of archaea. So quite a few new species would need to join Anthropobiota for it to rival the current Tree.
I seem to remember an accusation in some phylogenetics journal that a group of Archaea was outside the root of the Tree of Life, but I can't find it for the life of me. Anyway, there could be two or more separate Trees of Life. Anthropobiota will be a new one. The Tree of Synthetic Life.
Two different species within Anthropobiota need not evolve from other species in the same group. Each one could be created from scratch, by scientists in a lab. Once we develop the technology to reliably and inexpensively synthesize long genomes from nucleic acid precursors, and swap them for native genomes, we're in business. The flood gates for new species -- both benign and malign -- will open.
The Lifeboat Foundation A-Prize page is a foresightful effort to to put development of artificial life forms in the open, where it should be. It a reward to whoever creates the first life form that "must execute at least one synthetic nonbiological operation in order to complete its life cycle".
On the A-Prize page, Dr. Alan H. Goldstein, Professor of Biomaterials at Alfred University, creates four classifications of life: Natural Biological, Genetically-Engineered Biological, Synthetic Biological, and Synthetic Nonbiological (Animat). According to his classification system, Mycoplasma laboratorium would fall into the third category: Synthetic Biological. It will not be eligible to collect the A-Prize, because that would require an organism that integrates an entirely nonbiological, consistent (over generation) element into its biological life cycle.
Anyway, I'm looking forward to the creation of Mycoplasma laboratorium later this year. I hope that creating synthetic life stays expensive for at least a couple more decades.
Novel Biodiversity
The are several categories relating to the Tree of Life which I consider important.
The first category includes all extant creatures. By adolescence, we are familiar with thousands of animals. Scientists estimate there are somewhere between 5 and 100 million species altogether. Most are probably insects and arachnids, including over a million species of both mite and beetle.
The second category includes all species that have ever lived. This number is somewhere between 10 and 100 times greater than the number of extant creatures, therefore somewhere between 50 million and 10 billion. To me, making sense of the first category requires understanding the second. I am fascinated by the second category because most people don't know too much about it, and it's like visiting an alien world -- there are so many unusual and fascinating creatures in the fossil record.
The third category includes all species that could ever theoretically exist. We can really blow this up to huge proportions, including species based on something besides DNA, including non-carbon-based life forms, if they are physically possible, which seems likely. In this category I include alternate evolutionary paths.
In my view, there is a strong element of randomness to the specifics of evolution. In a parallel universe, Earth may have been inhabited by entirely different intelligences, born from an entirely different Tree of Life. Sauropsids may have become intelligent instead of synapsids, or something even more radical.
I like to draw my "circle of empathy" large -- so large, in fact, that I can go so far as to say that any form of self-reflective general intelligence with subjective experience is worthy of value, regardless of the biological context it grew up in. We can go even further and include non-conscious animals, though these may be considered as deriving their value from the appreciation of conscious beings.
When biotechnology advances to the point where can synthesize animal-sized genomes from scratch (we've already gotten to the level of bacteria), humans will surely create entirely new animals, both for study and pleasure. Leaving aside issues of regulation, I think that the first category will expand to include many elements of the second and third categories. Eventually, we will recognize that members of the second and third categories have the same inherent value as members of the first, and all will share the matter-energy resources of the local area.
So, as an environmentalist, I care about preserving existing biodiversity, but as a transhumanist environmentalist, I also care about the creation and preservation of de novo biodiversity. These creatures will provide an interesting accompaniment during our journey greening the Galaxy.
This may sound futuristic, but the first synthetic life will be created in a lab this year.
Bacterial Apocalypse?
A challenge in making people care about techno-apocalypse is that most of the proposed technologies which could cause it exist in the future, not the present.
There's all-out thermonuclear war, sure. If the Bush administration is dumb enough to attack Iran before he leaves office, then we could have serious problems with Russia (the country my family left when the Communists took over), whose minister of defense has cautioned the US not to lay a hand on Iran. If Putin's successor is as gangster as he is, then Cold War part II (or Hot War part I) can't be ruled out.
But would this kill everyone? Not too likely. Although burning cities do create black clouds which can initiate widespread crop failure, this effect is temporary. The world is a big place, and you can't nuke it all.
So, in examining possible sources of human extinction risk, we have to look to the future. In a way this is reassuring, because we have time to prepare, but in another way it's not, because some of the scenarios are too futuristic for people to take seriously.
I suppose the step after global thermonuclear war is genetically engineered plague. I've talked to four separate recombinant geneticists who say they would have a good chance at wiping out 90% of the human population in a decade if they had several million dollars and complete secrecy. (Their claims were more or less in tune even though they don't know one other, to my knowledge.) Are they exaggerating? I don't know, I'm not a biologist, but I think I'd rather err on the side of trusting them on this one.
What I do know about is history. The Black Death, which was possibly not the same thing as the bubonic plague, killed as much as half of Europe. Perhaps modern-day hygiene would prevent this from ever happening again, but the Spanish flu happened in conditions of nearly-modern hygiene, still killing 50-100 million, and spreading as far as the Arctic and remote Pacific islands (those are the two regions you need to watch if you care about extinction risk).
Would nuclear war threaten Tristan da Cunha, the most remote archipelago in the world? No. But a sufficiently powerful plague might. Especially a plague that spread to hundreds of millions of people before they started to display symptoms. Would such a thing be possible to genetically engineer? I've been talking with scientists about it since I got out of school but they often contradict each other, so I'm still confused.
My intuition tells me that when mankind can engineer something from scratch, it opens a vastly wider design space than nature alone could access. This is why humanity came up with computers, supersonic planes, and rocket ships, and the fastest swallow can't even break the sound barrier. That's why the Luddites got angry -- because specialized looms could create textiles way faster than they ever could. Perhaps specialized microbes could kill people faster than any conventional weapon, or even nuclear weapons. I'd rather not watch it in action to find out.
I like thinking about the genetically engineered bacteria because it's a happy medium in its future shock between thermonuclear war (which most accept as a possibility) and AI/robotics (which people have bizzare reactions to). There's also nanowar, but that is also more futuristic.
Synthetic Biology – Best Not to Ignore the Risks
Today's edition of Newsweek has an article on synthetic life, a topic of significant interest and concern. To use Alan Goldstein's classification scheme for various types of synthetic life, the kind being discussed here is Type 3, "synthetic biological", life forms with DNA/RNA programming, utilizing traditional biological building blocks such as proteins, with a genome synthesized from scratch in a laboratory. This is distinct from Type 2, "genetically-engineered biological" life forms, which are based on tweaks to preexisting genomes, and Type 4 life forms, "synthetic nonbiological", where DNA/RNA and traditional biological building blocks are not used and all functionality is engineered from scratch, like any machine.
The article reports that Craig Venter, famous for leading one of the first teams to sequence the human genome, has founded a new startup, Synthetic Genomics, which plans to make artificial organisms for converting sunlight into biofuel. Also interesting is that, apparently, some religious skeptics don't even believe that synthetic life can be produced. It's difficult to determine why. There are already millions of examples of functioning organisms coded by DNA, it seems odd that introducing a new one would somehow be physically forbidden. But creating life in a lab directly challenges religious fantasies that this is something only God can do. Everyone's favorite bioethicist, Leon Kass, is quoted in the article, saying, "I find it very hard to believe that, starting from scratch, we can somehow come up with a better [biological] system — one that's going to have much success." This is the same guy who believes that studying cadavers or eating ice cream in public are immoral.
Despite the odd pronouncements of anti-science dogmatists like Kass, we've been creating life and modifying genomes for thousands of years already, through selective breeding. Dogs, for instance. Many of the fruits we eat on a daily basis are modified versions of natural ancestors that were smaller, less nutritious, and more susceptible to the elements. Of course, there is a difference between selective breeding and creating new forms of life de novo. The latter is surely more powerful, but also more dangerous.
Rudy Rucker, a computer science professor made famous by his science fiction books, submitted a commentary on the topic of synthetic biology, also available on the Newsweek site. In the commentary, he dismisses away the dangers, saying, "What’s to stop a particularly virulent SynBio organism from eating everything on earth? My guess is that this could never happen. Every existing plant, animal, fungus and protozoan already aspires to world domination. There’s nothing more ruthless than viruses and bacteria—and they’ve been practicing for a very long time." He then goes on to talk extensively about some potentially radical benefits of the technology.
People like Rucker make transhumanism look bad, by spending all their time talking about the benefits, while handwaving away the risks. Synthetic biology will indeed be a serious global risk. The huge difference between intelligent engineering and blind natural selection should be obvious to someone as educated as Rucker, but apparently not. If I am knowledgeable about biology and have the tools to create new organisms from scratch, then it would be entirely plausible I could certainly construct something that poses a threat to all extant life.
The intelligent construction of synthetic organisms opens up a vastly wider design space than the one previously exploited by evolution and natural selection. In evolution, every genetic step must be independently adaptive, forcing a path through local maxima. Evolution cannot plan ahead, or intelligently construct adaptations oriented towards solving environmental challenges in the most general possible way. Evolution does not understand the concept of over-designing or fault tolerances - for an organism to be successful, it just has to reproduce a little bit faster than its competition, not ten times faster. When humans design a bridge, we design it to withstand a weight tens of times greater than its average load. Evolution can do no such thing.
One day, some synthetic biologist will become capable of designing a supervirus that can wipe out humanity. Then, ten will, then a hundred, and eventually, thousands. That's the nature of scientific knowledge - the bleeding edge of today is the used textbooks of tomorrow. Information wants to be free. Because synthetic biology will definitely become a real threat in the future, we have to start taking steps now to ensure that the field has proper regulation and oversight. SynBioSafe, a two-year, $312,000 project set up by the European Commission, is an excellent step in this direction.
Even if we think the chance of any given synthetic biology project in any given year leading to a global disaster is relatively small, over sufficiently long timeframes and for sufficiently many projects, the probability reaches unity. Synthetic biology is much more worrisome than global warming, nuclear war, or peak oil, because these things cannot kill everyone while synthetic biology can.