Labtimes 2017-06

page 16 Lab Times 6-2017 Analysis Ants’ Superpowers Ants are fascinating creatures. They are able to learn, farm and, as scientists recently confirmed, some species can even sense active tectonic faults. Strange animal behaviour Pixabay/7854 I n 2013, Gabriele Berberich’s seminar on earthquake prediction at the Euro- pean Geosciences Union’s annual meet- ing, in Vienna, caused shock waves among the audience. Berberich, a geologist at Uni- versity Duisburg-Essen, in Germany, pre- sented tantalising results from her field- work, showing that red wood ants (Formica rufa -group) change their behaviour hours before an earthquake. Shortly after Ber- berich gave her presentation, headlines in the mainstream media boldly claimed that “ants lead the way on earthquake predic- tion” or that “ants can save millions from earthquakes”. This was huge. Despite dec- ades of research, geologists continue strug- gling to predict earthquakes more than a few minutes in advance, which is obvious- ly not long enough to evacuate people from affected areas. Could these ants come to save the day? Sense disaster Tales of abnormal animal behaviours before an earthquake have been around for centuries. In 373 BC, Diodorus, a Greek his- torian, reported that rats, snakes, weasels, centipedes, worms and beetles migrated in droves a few days before a violent earth- quake hit the city of Helice, in Greece. Ac- counts of animals in panic seconds to hours before an earthquake are the most com- mon, for example, dogs barking or whin- ing, nervous cats (sometimes jumping out of windows), bees leaving their hives, cows producing less milk, to name a few. Weird behaviour in Asia China and Japan are, by far, the coun- tries that have invested most resources into studying a connection between ani- mal behaviour and earthquakes. In 1975, an earthquake of magnitude 7.3 was pre- dicted months in advance in China, based on accounts of weird animal behaviour, in- cluding snakes coming out of hibernation and freezing on the ground surface, and rats leaving their holes en masse . The city of Haicheng, with a population of a mil- lion people, was evacuated days before the earthquake, saving thousands of lives. However, this earthquake was preceded by many smaller temblors (called foreshocks) over several months, which was probably what really convinced Chinese officials to order the evacuation. So, despite nearly four decades of research, there is still no evidence that abnormal animal behaviour can be predictive of earthquakes, well, at least not reliably. Scientists remain skeptical because re- ports of this kind are typically collected af- ter the quake, so people are biased to re- call behaviours that might have always been there – they just didn’t notice them. The other reason is that while it is easy to explain why animals sense earthquakes seconds before they start (they can feel a type of weak seismic wave that reaches the Earth’s surface seconds before stronger, more noticeable waves), it’s more difficult to understand how they may do this days or weeks in advance. Some scientists have suggested these animals detect electromagnetic changes or gases released from the ground before earthquakes but most animals definitely can’t do this. For ants though, it’s a differ- ent story. Can ants predict earthquakes? Red wood ants are remarkably sensitive to their environment. Besides detecting the tiniest changes in temperature, ants can re- spond to electromagnetic fields and have protein receptors that sense changes in car- bon dioxide (CO 2 ) concentrations. So, could these ants sense earthquakes long before they start? Berberich and Ulrich Schreiber, her former PhD supervisor at the Univer-

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