The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution

"Yes, I do. Richard Dawkins is such a great writer. I could have chosen any of his books, really, because they’re all about evolution , and evolution is extremely important in understanding viruses. They mutate so quickly that new variants can emerge in days. So we really need to know how this can happen. When viruses get into living cells, and reproduce, they produce millions of new viruses. Therefore, within those millions, there are going to be several mutants. If any of those mutants happen to have a selective advantage – perhaps they can spread further, survive longer, infect more easily, or be less deadly – they will take over. Yes, it’s not generally advantageous for viruses to kill their host, because then they die with them and the chain of infection is broken. Very rapidly one new mutant with a selection advantage can replace the whole population. So, viruses absolutely depend on evolution for survival. Dawkins called one of his books The Blind Watchmaker and viruses are totally blind but appear very sophisticated. It’s extraordinary. Dawkins has a wonderful way of expressing himself in writing, and his books have informed all my writing about viruses, because they’ve given me a feeling for evolution. I knew what evolution was of course, but the examples he chooses, and the elegant way he writes… I just find it so insightful. The Ancestor’s Tale is my favourite, because it’s so clever. Its structure is inspired by Chaucer ‘s The Canterbury Tales : it’s a pilgrimage through human existence. The pilgrims are walking backwards through human evolution. Every so often they meet up with our earlier cousins. First they meet other primates starting with chimpanzees, for example, because they are our closest cousin. We separated from them about 6 million years ago. On it goes until eventually they start meeting bacteria. I loved that; I thought it was brilliant. Yes. I come from a medical angle. So, I would have regarded a mutation as an abnormal gene that someone inherited from one of their parents, causing a congenital disease. But with viruses it’s their reason for being. If they can’t evolve, they’ve had it. They’re not going to survive. So they’re doing it all the time, and we are always one step behind. Not really, but there are plenty of viruses that are not harmful. And there are plenty that don’t infect us, but infect other organisms – plants, say. Some viruses that lethally infect bacteria and algae thereby apparently control their populations in the oceans. We are now using viruses to transfer genes into humans. Because viruses are so good at infecting us, we can take out the harmful genes and replace them with genes that we want to give to somebody – for example a piece of DNA that codes for a foreign protein that scientists want to test as a vaccine. So they infect a person with this altered virus and it will multiply inside them and hopefully induce an immune response to the foreign protein it is carrying. Support Five Books Five Books interviews are expensive to produce. If you're enjoying this interview, please support us by donating a small amount . There are other viruses – for example, the virus that I worked on, the Epstein-Barr virus – that are so successful that they infect virtually everybody worldwide. I know it sounds incredible, but the majority of people wouldn’t know they have it. It’s not an advantage to have it, but then again, it is not a disadvantage , unless you happen to be one of the few people who do have a problem with it. There are quite a lot of viruses like that, that we’re now discovering. Of course, when virologists were focussed on hunting for viruses that cause specific diseases, they never found these ones because they are mainly silent infections. Yes, certainly. It’s thought that when humans changed from being hunter-gatherers to farmers, beginning around 10,000 years ago, they came into much closer contact with domestic animals, and many of the animal viruses jumped to humans. At first, many were probably quite deadly. But the really vicious viruses in a population killed their hosts and immediately died with them, so it was the less virulent ones that survived. I think smallpox has always been the most lethal, but even it apparently got less deadly over time. Also, over time, humans developed genetic resistance as the infections killed off the most susceptible. The genetically less susceptible survived, and we are all offspring of those people. Yes, but a lot slower than viruses. They’re always one step ahead. Let me first say that George Klein was a wonderfully clever thinker and a great research virologist. I love that quote. But, no, I have faith in the human race. I think we are genetically diverse enough for there always to be some people who will be able to survive infection with any ‘new’ virus that comes along."