Biology’s Big Bang
NATURE is full of surprises. When atoms were first proved to exist (and that was a mere century ago), they were thought to be made only of electrons and protons. That explained a lot, but it did not quite square with other observations. Then, in 1932, James Chadwick discovered the neutron. Suddenly everything made sense—so much sense that it took only another 13 years to build an atomic bomb.
It is probably no exaggeration to say that biology is now undergoing its “neutron moment”. For more than half a century the fundamental story of living things has been a tale of the interplay between genes, in the form of DNA, and proteins, which the genes encode and which do the donkey work of keeping living organisms living. The past couple of years, however, have seen the rise and rise of a third type of molecule, called RNA.
The analogy is not perfect. Unlike the neutron, RNA has been known about for a long time. Until the past couple of years, however, its role had seemed restricted to fetching and carrying for DNA and proteins. Now RNA looks every bit as important as those two masters. It may, indeed, be the main regulator of what goes on in a cell—the cell’s operating system, to draw a computing analogy—as well as the author of many other activities (see article). As important, molecular biologists have gone from thinking that they know roughly what is going on in their subject to suddenly realising that they have barely a clue. That might sound a step backwards; in fact, it is how science works. The analogy with physics is deeper than just that between RNA and the neutron. There is in biology at the moment a sense of barely contained expectations reminiscent of the physical sciences at the beginning of the 20th century. It is a feeling of advancing into the unknown, and that where this advance will lead is both exciting and mysterious.
As Samuel Goldwyn so wisely advised, never make predictions—especially about the future. But here is one: the analogy between 20th-century physics and 21st-century biology will continue, for both good and ill.
Physics gave two things to the 20th century. The most obvious gift was power over nature. That power was not always benign, as the atomic bomb showed. But if the 20th century was distinguished by anything from its predecessors, that distinctive feature was physical technology, from motor cars and aeroplanes to computers and the internet. It is too early to be sure if the distinguishing feature of the 21st century will be biological technology, but there is a good chance that it will be. Simple genetic engineering is now routine; indeed, the first patent application for an artificial living organism has recently been filed (see article). Both the idea of such an organism and the idea that someone might own the rights to it would have been science fiction even a decade ago. And it is not merely that such things are now possible. The other driving force of technological change—necessity—is also there. Many of the big problems facing humanity are biological, or are susceptible to biological intervention. The question of how to deal with an ageing population is one example. Climate change, too, is intimately bound up with biology since it is the result of carbon dioxide going into the air faster than plants can remove it. And the risk of a new, lethal infection suddenly becoming pandemic as a result of modern transport links (see article) is as biological as it gets. Even the fact that such an infection might itself be the result of synthetic biology only emphasises the biological nature of future risks.
At the moment, policymakers have inadequate technological tools to deal with these questions. But it is not hard to imagine such tools. Ageing is directly biological. It probably cannot be stopped, but knowing how cells work—really knowing—will allow the process to be transformed for the better. At least part of the answer to climate change is fuel that grows, rather than fuel that is dug up. Only biotechnology can create that. And infections, pandemic or otherwise, are best dealt with by vaccines, which take a long time to develop. If cells were truly understood, that process might speed up to the point where the vaccine was ready in time to do something useful.
But physics gave the 20th century a more subtle boon than mere power. It also brought an understanding of the vastness of the universe and humanity’s insignificant place in it. It allowed people, in William Blake’s phrase, to hold infinity in the palm of a hand, and eternity in an hour.
Biology, though, does more than describe humanity’s place in the universe. It describes humanity itself. And here, surprisingly, the rise of RNA may be an important part of that description. Ever since the human-genome project was completed, it has puzzled biologists that animals, be they worms, flies or people, all seem to have about the same number of genes for proteins—around 20,000. Yet flies are more complex than worms, and people are more complex than either. Traditional genes are thus not as important as proponents of human nature had suspected nor as proponents of nurture had feared. Instead, the solution to the puzzle seems to lie in the RNA operating system of the cells. This gets bigger with each advance in complexity. And it is noticeably different in a human from that in the brain of a chimpanzee.
If RNA is controlling the complexity of the whole organism, that suggests the operating system of each cell is not only running the cell in question, but is linking up with those of the other cells when a creature is developing. To push the analogy, organs such as the brain are the result of a biological internet. If that is right, the search for the essence of humanity has been looking in the wrong genetic direction.
Of course, such results are speculative and primitive. But that is the point. Lord Rutherford, who proved that atoms exist, knew nothing of neutrons. Chadwick knew nothing of quarks, let alone supersymmetry. Modern biologists are equally ignorant. But eventually, the truth will out.
(June 14th 2007, The Economist)