During my internship with the German history magazine G Geschichte in 2016, I interviewed Dr Chris Allen, a microbiologist from Queen’s University Belfast about the potential discovery of Hannibal’s route over the Alps in 218 BC. Dr Allen had, along with Bill Mahaney from York University in Toronto, led expeditions to the proposed route over the past few years and published their findings in the journal Archaeometry.
G/Geschichte: Dr Allen, what got you interested in the Hannibal story?
Dr Chris Allen: On a personal level I’ve always been interested in ancient history. But I met this chap called Bill Mahaney who was very interested in the whole story and had been studying the various theories for where Hannibal crossed the Alps for 30 or 40 years. I was on an expedition with him in 2011. As a microbiologist I was bringing something new to the table, so we were able to come up with some ideas of how we might be able to test whether this genuinely was the route he took. The circumstantial evidence that Hannibal took the Col de Traversette was quite convincing. This is largely based upon the interpretation of the ancient texts by people like Sir Gavin de Beer and also by analysis of the geology, for example examinations of rockfalls. If we could find a watering hole where he would have watered his animals we should be able to find some evidence of his passage. Talking to various people who have an interest in working with horses, it was clear that horses have to defecate when they drink. I also knew from studying the literature that horse manure is mainly comprised of a group of organisms called Clostridia. These clostridia produces something called endospores which are very stable in soil, a bit like genetic time capsules. So if the clostridia had been deposited there, there would be some indication because the endospores that would be associated with the clostridia would still be there. We would see if we could correlate the exact date he passed through the Alps with an abundance of the clostridia, using carbon dates.
Hannibal’s expedition is particularly remarkable considering he took elephants over the Alps. In one of your interviews you mentioned the possibility of finding an elephant tapeworm egg? Is that still something you are looking to achieve?
That’s still a possibility. We know that he had 15000 to 20000 horses. If you can imagine 20000 horses stood in a field for two days, you can imagine, there would be a lot of mess left behind. We know that he didn’t have anywhere near that number of elephants, I think Polybius said he had 37 elephants. So we are talking about much lower numbers. The other thing is that I have a colleague here at Queens who has worked with elephants. She told me that you will never find elephants and horses together, as horses are petrified of elephants, which is partly why Hannibal used elephants, against the enemy cavalry I think. What I’m saying is it’s quite possible that the elephants were watered somewhere else, that they weren’t actually in that mire.
You mentioned Polybius who wrote one of the main accounts we have on Hannibal’s trip. The other one was by Livy: are there any concerning points of contention between these two sources?
What you have to remember is Polybius was writing just a few years after the expedition, I think he was even born when Hannibal was still alive, whereas Livy was writing about 200 years afterwards. So it’s like us today writing about the battle of Waterloo, you are very much talking as a historian rather than as someone who was contemporary to the event. We know that Polybius actually walked the route which Hannibal took, whereas Livy didn’t: he never left his base in what is now Turin. So some big differences. Those are the two accounts that most people tend to use to defend their arguments. These significant differences have led to a lot of debate. We’ve had 2000 years of various individuals even up to the modern day disagreeing about the route he took across the Alps. This is I think one of the things which makes the story so interesting from the point of view of the general public: it’s a big unanswered question. We are very much following more on the side of Polybius, rather on the side of Livy. We think that some of the things Livy said may not actually be correct. From my point of view as a microbiologist, I would like to focus on trying to analyse the issue from a purely scientific perspective.
You just mentioned that you are a microbiologist. In a few accounts of his journey, it is said that Hannibal used vinegar to soften the boulders which were obstructing his path. As a microbiologist, what would you say to that?
Well that’s actually from Livy, not Polybius-that’s one of the bones of contention. My colleague Bill Mahaney believes that it is completely fictional. His argument is based upon what I would call a “negative result”. In other words what he is saying is that because you can’t find any evidence of boulders being split, what Livy said must be fictional. What I would say as a sceptical scientist is that if you don’t find something it doesn’t mean its not there-we tend to work on finding evidence rather than not finding evidence. Actually there is no evidence on any of the routes of boulders being split by heat and then being cooled by vinegar, but who knows? With negative results it is always very difficult; you never know whether you have just not found it or if it is really not there.
“20000 horses stood in a field for two days, you can imagine, there would be a lot of mess left behind”
Going back to Hannibal’s journey, what made Hannibal decide to cross the Alps with his armies, and particularly in a time of winter? We’d see that as a bit of a ridiculous decision.
It was, yes, and that is actually one of the main arguments that people make for the alternative routes, because the Traversette route is one of the highest passages of the Alps (almost 3000 metres above sea level) and one of the most treacherous, especially on the Italian side. Polybius actually talks about this in his account, about the fact that Hannibal lost a huge number of his men and animals when he was trying to descend. What we think is that he was probably driven there. This is coming from Gavin de Beer who wrote about this a few years ago, the first guy in the modern era who proposed this route. We have to remember that at that this is pre Roman Empire, the Roman civilisation was relatively young. That part of France was not occupied by Rome at all, it was actually occupied by the Gauls, the dominant military force in the area. There were a number of different tribes of Gauls, and one very powerful tribe were called the Allobroges. The Allobroges were like the military super power. Hannibal was obviously a brilliant general, a brilliant organiser; he probably weighed up the probabilities, does he take the Allobroges on on one of the other routes and head into a full scale battle, or does he try and slip in through a back door. I guess he made the decision that he would do better by slipping in the back door.
Hannibal’s trip was more than crossing over the Alps, he also crossed the Pyrenees and the Rhone river as well. There isn’t any strong evidence concerning his route over the Pyrenees. In terms of further research would you ever consider analysing his trip over the Pyrenees for example?
If I had the opportunity I would yes, without a doubt. I think you have to start with a good hypothesis. Its like making a movie, if you want to make a good movie you have to start off with a good script, so if you want to do some good science you have to start off with a good hypothesis. To be honest with you at the moment we are putting all our effort into trying to generate a strong set of data for this route. It seems to be a story which has gripped everyone’s imagination. We feel now we have to deliver more data as promised. So hopefully in the next year or two we will be able to do that.
Wonderful, thank you so much.