Josh Witten

What did you do on your summer vacation?  Go to the beach?  Space camp?  Visit grandma?  In 1959, Cambridge engineering student John Hoyte and friends hiked across the Alps with Jumbo the elephant.

In its most formal sense, the scientific method begins with a question: Why did A happen?  At least two potential answers, called hypotheses¹, are postulated (e.g., H₀ and H₁).  Having at least two distinct hypotheses is critical, because experiments do not "prove" a hypothesis.  Experiments distinguish between hypotheses.  This intellectual construct takes the form: if H₀ is more likely, we will observe X result from the experiment; if H₁ is more likely, we will observe Y result.  Frequently, one hypothesis is the null hypothesis (H₀), which is generally stated as: A happened because of random chance.  Science favors the hypothesis that best predicts the result², leading to progressive refinement of the hypotheses and improvement of this predictive power.

All scientific disciplines - be they physics, biology, economics, or history - follow this formalism, but differ in their ability to conduct direct experimental tests, where scientists intentional manipulate specific variables over specific ranges) of the proposed hypotheses.  While biochemists can frequently isolate the single variable they wish to test, ecologists are often restricted, by the scale and complexity of their subject, to conducting observational studies, where scientists observe the different states of a variable available naturally.  Similarly, the scale and complexity of history makes direct experimentation only possible for the technical details (e.g., can a bodkin arrow fired from a longbow effectively penetrate plate mail?) or demonstrations of possibility³ (i.e., demonstrating that something could be done with materials available at the time⁴).  In general, history is restricted to observational experiments.

What does a mountaineering elephant have to do with the scientific method?  Hannibal Barca easily ranks as one of the most influential figures in the history of the ancient Mediterranean.  Although Hannibal nearly brought the fledgling Roman Empire to its knees, the steel of Roman Imperialism was forged in the crucible of Hannibal's Italian campaign (218-203 BCE) during the Second Punic War. 
The legendary winter crossing of the Alps (218 BCE) to invade Italy is symbolic of the Carthaginian general's aggressiveness and unpredictability.  This event⁷ has captivated historians ever since.  Our knowledge of this fascinating event, however, comes from second-hand sources.  None of the writers saw the crossing happen.  Ambiguity has sparked obsessive debate in academic circles over precisely which pass Hannibal used.

The British Alpine Hannibal Expedition asked a basic question.  According to the chroniclers, Hannibal crossed the Alps with 37 surviving elephants.  This meant that the pass Hannibal used must have been able to be crossed by an elephant. 

Q: Can the Alps be crossed by an elephant?

Hoyte was proposing two hypotheses:

H₀: An elephant cannot cross the Alps.
H₁: An elephant can cross the Alps.

The British Alpine Hannibal Expedition planned an experiment that would distinguish between these two hypotheses.  They would walk an Asian elephant (Elephas maximus) from France to Susa, Italy across the Alps.

If H₀, then the elephant would not arrive in Susa.
If H₁, then the elephant would arrive in Susa.

They simply needed the necessary materials. 

Materials:
1 Elephas maximus
1 Alps

Fortunately, the Turin Zoo was generous enough to provide the non-geological materials.  Her name was Jumbo^8,9.
Jumbo traveled 150 miles in 10 days from France to invade Susa, Italy¹⁰; a result inconsistent with the null hypothesis (H₀) and consistent with the alternative hypothesis (H₁).  The result of the British Alpine Hannibal Expedition's experiment suggests that elephants can cross the Alps.

Like all good research, the British Alpine Hannibal Expedition raised more questions than it answered.  To protect human and elephant health, this preliminary test was done in summer.  Can an elephant cross the Alps in October (as in Hannibal's case)?  What other passes can be crossed by elephants?  Can these single elephant preliminary results be replicated by independent researchers?  Do single elephant results represent those of multiple elephants (say 37 of them)?  I'm sure that the internet's smartest readers can come up with even more questions.

And that, folks, is how hypothesis directed research is done.  If, like me, you find the concept of marching elephants across the Alps to test your theories, I highly recommend that you listen to John Hoyte describe the British Alpine Hannibal Expedition in his own words as a special lecture from Patrick Hunt's Hannibal series from Stanford on iTunes U.

1: Greek for "little, tiny, adorbaly cute thesis".
2: In the case where both hypotheses are equally predictive, science favors the hypothesis that makes the fewest assumptions (Occam's Razor).  The null hypothesis is, by definition, the hypothesis with the fewest possible assumptions.
3: I like to call this MythBusters^TM science.
4: As these tests only demonstrate that an event is possible, it neither demonstrates that the method use is how an event occurred, nor does a failure indicate that it was not possible⁵.
5: Formally, it is impossible to "prove⁶ a negative".
6:Philosophers of science still debate whether one can actually "prove" - in the formal sense, not the popular post-modern sense - anything.
7: Singular not for the crossing of the Alps, but for the time of year (October).
8: Lest you fear for the safety of the pachyderm, Jumbo's well-being was continually monitored by one of pre-eminent large animal veterinarians in England, who had extensive experience with elephants during WWII (nothing like wars to equip talented individuals with unusual qualifications), and the Italian Society for the Prevention of Cruelty to Animals.  Extensive safety precautions were taken, including the fabrication of some of the largest, Italian, leather shoes ever.
9: Despite the best efforts to call her Hannibella, Jumbo remained responsive to only her given name.
10: They originally planned to cross the Col du Clapier, which, although controversial, is the pass also favored by Hoyte and Stanford geoarchaeologist and Hannibal expert Patrick Hunt as the pass Hannibal used.  Rock falls forced the expedition to cross the Col du Mont Cenis instead.