We should be very worried indeed about bionanotechnology, according to Alan Goldstein, a biomaterials scientist from Alfred University, who has written a long article called I Nanobot on this theme in the online magazine Salon.com. According to this article, we are stumbling into creating a new form of life, which is, naturally, out of our control. “And Prometheus has returned. His new screen name is nanobiotechnology.” I think that some very serious ethical issues will be raised by bionanotechnology and synthetic biology as they develop. But this article is not a good start to the discussion; when you cut through Goldstein’s overwrought and overheated writing, quite a lot of what he says is just wrong.
Goldstein makes a few interesting and worthwhile points. Life isn’t just about information, you have to have metabolism too. A virus isn’t truly alive, because it consists only of information – it has to borrow a metabolism from the host it parasitises to reproduce. And our familiarity with one form of life – our form, based on DNA for information storage, proteins for metabolic function, and RNA to intercede between information and metabolism – means that we’re too unimaginative about conceiving entirely alien types of life. But the examples he gives of potentially novel, man-made forms of life reveal some very deep misconceptions about how life itself, at its most abstract, works.
I don’t think Goldstein really understands the distinction between equilibrium self-assembly, by which lipid molecules form vesicles, for example, and the fundamentally out-of-equilibrium character of the self-organisation characteristic of living things. I am literally not the same person I was when I was twenty; living organisms are constantly turning over the molecules they are made from; the patterns persist, but the molecules that make up the pattern are constantly changing. So his notion that if we make an anti-cancer drug delivery device with an antibody that targets a certain molecule on a cell wall, then that device will stay stuck there through the lifetime of the organism, and if it finds its way to a germ cell it will be passed down from generation to generation like a retrovirus, is completely implausible. The molecule that it’s stuck to will soon be turned over, the device itself will be similarly transient. It’s because the device lacks a way to store the information that would be needed to continually regenerate itself that it can’t be considered in any sensible way living.
If rogue, powered vesicles lodging in our sperm and egg cells aren’t scary enough, Goldstein next invokes the possibility of the meddling with the spark of life itself – electricity. But the moment we close that nano-switch and allow electron current to flow between living and nonliving matter, we open the nano-door to new forms of living chemistry — shattering the “carbon barrier.” This is, without doubt, the most momentous scientific development since the invention of nuclear weapons.” This sounds serious, but it seems to be founded on a misconception of how biology uses electricity. Our cells burn sugar, Goldstein says, which “yields high-energy electrons that are the anima of the living state. “ Again, this is highly misleading. The energy currency of biology isn’t electricity, it’s chemistry – specifically it’s the energy containing molecule ATP. And when electrical signals are transmitted, through our nerves, or to make our heart work, it isn’t electrons that are moving, it’s ions. Goldstein makes a big deal out of the idea of a Biomolecule-to-Material interface between a nanofabricated pacemaker and the biological pacemaker cells of the heart. “A nanofabricated pacemaker with a true BTM interface will feed electrons from an implanted nanoscale device directly into electron-conducting biomolecules that are naturally embedded in the membrane of the pacemaker cells. There will be no noise across this type of interface. Electrons will only flow if the living and nonliving materials are hard-wired together. In this sense, the system can be said to have functional self-awareness: Each side of the BTM interface has an operational knowledge of the other.” This sounds like a profound and disturbing blurring of the line between the artificial and the biological. The only trouble is, it’s based on a simple error. Pacemaker cells don’t have electron-conducting biomolecules embedded in their membranes; the membrane potentials are set up and relaxed by the flow of ions through ion channels. There can be no direct interface of the kind that Goldstein describes. Of course, we can and do make artificial interfaces between organisms and artefacts – the artificial pacemakers that Goldstein mentions are one example, and cochlear implants are another. The increasing use of this kind of interface between artefacts and human beings does already raise ethical and philosophical issues, but discussion of these isn’t helped by this kind of mysticism built on misconception.
In an attempt to find an abstract definition of life, Goldstein revives a hoary old error about the relationship between the second law of thermodynamics and life: “The second law of thermodynamics tells us that all natural systems move spontaneously toward maximum entropy. By literally assembling itself from thin air, biological life appears to be the lone exception to this law. “ As I spent several lectures explaining to my first year physics students last semester, what the second law of thermodynamics says is that isolated systems tend to maximum entropy. Systems that can exchange energy with their surroundings are bound only by the weaker constraint that as they change, the total entropy of the universe must not decrease. If a lake freezes, the entropy of the water decreases, but as the ice forms it expels heat which raises the entropy of its surroundings by at least as much as its own entropy decreases. Biology is no different, trading local decreases of entropy for global increases. Goldstein does at least concede this point, noting that “geodes are not alive”, but he then goes on to say that “nanomachines could even be designed to use self-assembly to replicate”. This statement, at least, is half-true; self-assembly is one of the most important design principles used by biology and it’s increasingly being exploited in nanotechnology too. But self-assembly is not, in itself, biology – it’s a tool used by biology. A system that is organised purely by equilibrium self-assembly is moving towards thermodynamic equilibrium, and things that are at equilibrium are dead.
The problem at the heart of this article is that in insisting that life is not about DNA, but metabolism, Goldstein has thrown the baby out with the bathwater. Life isn’t just about information, but it needs information in order to be able to replicate, and most centrally, it needs some way of storing information in order to evolve. It’s true that that information could be carried in other vehicles than DNA, and it need not necessarily be encoded by a sequence of monomers in a macromolecule. I believe that it might in principle be possible in the future to build an artificial system that does fulfill some general definition of life. I agree that this would constitute a dramatic scientific development that would have far-reaching implications that should be discussed well in advance. But I don’t think it’s doing anyone a service to overstate the significance of the developments in nanobiotechnology that we are seeing at the moment, and I think that scientists commenting on these issues do have some obligation to maintain some standards of scientific accuracy.