“The question of whether a computer can think is no more interesting than the question of whether a submarine can swim.” -- Edsger W. Dijkstra.

A dog can herd sheep, smell land mines, pull a sled, guide a blind person, and even warn of oncoming epileptic seizures.

A computer can calculate a spreadsheet, typeset a document, play a video, display web pages, and even predict the weather.

The question of which one is “better” is silly. They're both incredibly useful, and both can be adapted to amazingly diverse tasks. The dog is more adaptable for tasks in the physical world--and does not require engineering to learn a new task, only a bit of training. But the closest a dog will ever come to displaying web pages is fetching the newspaper.

Engineering takes a direct approach to solving tasks that can be described with precision. If the engineering is sound, the designs will work as expected.
Engineered designs can then form the building blocks of bigger systems. Precisely mixed alloys make uniform girders that can be built into reliable bridges. Computer chips are so predictable that a million different computers running the same computer program can reliably get the same result. For simple problems, engineering is the way to go.

Biology has never taken a direct approach, because it has never had a goal. Organisms are not designed for their environment; they are simply the best tiny fraction of uncountable attempts to survive and replicate.
Over billions of years and a vast spectrum of environments and organisms, the process of trial and error has accumulated an awesome array of solutions to an astonishing diversity of problems.

Until recently, biology has been the only agent that was capable of making complicated structures at the nanoscale. Not only complicated structures, but self-reproducing structures: tiny cells that can use simple chemicals to make more cells, and large organisms made of trillions of cells that can move, manipulate their environment, and even think. (The human brain has been called the most complex object in the known universe.) It is tempting to think that biology is magic.
Indeed, until the mid-1800's, it was thought that organic chemicals could not be synthesized from inorganic ones except within the body of a living organism.

The belief that there is something magical or mystical about life is called “vitalism,” and its echoes are still with us today. We now know that any organic chemical can be made from inorganic molecules or atoms.

But just last year, I heard a speaker—at a futurist conference, no less—advance the theory that DNA and protein are the only molecules that can support self-replication. Likewise, many people seem to believe that the functionality of life, the way it solves problems, is somehow inherently better than engineering: that life can do things inaccessible to engineering, and the best we can do is to copy its techniques. Any engineering design that does not use all the techniques of biology is considered to be somehow lacking.

If we see people scraping and painting a bridge to avoid rust, we may think how much better biology is than engineering: the things we build require maintenance, while biology can repair itself. Then, when we see a remora cleaning parasites off a shark, we think again that biology is better than engineering: we build isolated special-purpose machines, while biology develops webs of mutual support. But in fact, the remora is performing the same function as the bridge painters. If we want to think that biology is better, it's easy to find evidence. But a closer look shows that in many cases, biology and engineering already use the same techniques.

Biology does use some techniques that engineering generally does not.
Because biology develops by trial and error, it can develop complicated and finely-tuned interactions between its components. A muscle contracts when it's signaled by nerves. It also plays a role in maintaining the proper balance of nutrients in the blood. It generates heat, which the body can use to maintain its temperature. And the contraction of muscles helps to pump the lymph. A muscle can do all this because it is made of incredibly intricate cells, and embedded in a tightly-integrated body. Engineered devices tend to be simpler, with one component performing only one function. But there are exceptions.

The engine of your car also warms the heater. And the electricity that it generates to run its spark plugs and fuel pump also powers the headlights.

Complexity deserves a special mention. Many non-engineered systems are complex, while few engineered systems are. A complex system is one where slightly different inputs can produce radically different outputs.

Engineers like things simple and predictable, so it's no surprise that engineers try to avoid complexity. Does this mean that biology is better? No, biology usually avoids complexity too. Even complex systems are predictable some of the time—otherwise, they'd be random.

Biology is full of feedback loops with the sole function of keeping complex systems from running off the rails. And it's not as though engineered devices are incapable of using complexity. Turbulence is complex. And turbulence is a great way to mix substances together.

Your car's engine is finely sculpted to create turbulence to mix the fuel and the air.

Biology flirts with complexity in a way that engineering does not.
Protein folding, in which a linear chain of peptides folds into a 3D protein shape, is complex. If you change a single peptide in the protein, it will often fold to a very similar shape—but sometimes will make a completely different one. This is very useful in evolving systems, because it allows a single system to produce both small and large changes. But we like our products to be predictable: we would not want one in a thousand cars sold to have five wheels, just so we could test if five was better than four. Evolution is beginning to be used in design, but it will probably never be used in the manufacture of final products.

Copying the techniques of life is called “biomimesis.” There's nothing wrong with it, in moderation. Airplanes and birds both have wings. But airplane wings do not have feathers, and airplanes do not digest seeds in mid-air for fuel. Biology has developed some techniques that we would do well to copy. But human engineers have also developed some techniques that biology never invented. And many of biology's techniques are inefficient or simply unnecessary in many situations.
Sharks might not need remoras if they shed their skin periodically, as some trees and reptiles do.

The design of nanomachines and nanosystems has been a focus of controversy. Many scientists think that nanomachines should try to duplicate biology: that the techniques of biology are the best, or even the only, techniques that can work at the nanometer scale. Certainly, the size of a device will have an effect on its function. But the device's materials also have an effect. The materials of biology are quite specialized. Just a few chemicals, arranged in different patterns, are enough to make an entire organism. But organic chemicals are not the only kind of chemicals that can make nanoscale structures.

Organics are not very stiff; they vibrate and even change shape. They float in water, and the vibrations move chemicals through the water from one reaction site to another.

A few researchers have proposed building systems out of a different kind of chemistry and machinery. Built of much stiffer materials, and operating in vacuum or inert gas rather than water, it would be able to manufacture substances that biology cannot, such as diamond. This has been widely criticized: how could stiff molecular machines work while fighting the vibrations that drive biological chemicals from place to place? But in fact, even in a cell, chemicals are often actively transported by molecular motors rather than being allowed to diffuse randomly. And even the stiff machine designs use vibration when it is helpful; for example, a machine designed to bind and move molecules might jam if it grabbed the wrong molecule, and Drexler has calculated that thermal noise could be effective at un-jamming it. (See Nanosystems section 13.2.1.d.)

Engineering and biology alike are very good at ignoring effects that are irrelevant to their function. Engineers often find it easier to build systems a little bit more robustly, so that no action is necessary to keep them working as designed in a variety of conditions. Biology, being more complicated and delicate, often has to actively compensate or resist things that would disrupt its systems. So for the most part, stiff machines would not “fight” vibrations—they'd simply ignore them.

Biology still has a few tricks we have not learned. Embryology, immunology, and the regulation of gene expression are still largely mysterious to us. We have not yet built a system with as much complexity as an insect, so we cannot know whether there are techniques we haven't even noticed yet that help the insect deal with its environment effectively. But even with the tricks we already know, we can build machines far more powerful—for limited applications—than biology could hope to match. (How many horses would fit under the hood of a 300-horsepower sports car?) These tricks and techniques, with suitable choices and modifications, will work fine even at the molecular scale. Engineering and biology techniques overlap substantially, and engineering already has enough techniques to build complete machine systems—even self-contained manufacturing systems—out of molecules.

This may be threatening to some people, who would rather see biology retain its mystery and preeminence. But at the molecular level, biology is just machines and structures.

The Center for Responsible Nanotechnology(TM) (CRN) is an affiliate of World Care(R), an international, non-profit, 501(c)3 organization. All donations to CRN are handled through World Care. The opinions expressed by CRN do not necessarily reflect those of World Care.

Chris has studied nanotechnology and molecular manufacturing for more than a decade. After successful careers in software engineering and dyslexia correction, Chris co-founded the Center for Responsible Nanotechnology in 2002, where he is Director of Research. Chris holds an MS in Computer Science from Stanford University.

Copyright © 2004 Chris Phoenix