Bat sonar gets more sophisticated, according to a report in ScienceDaily 13 September 2011 and PLoS Biology, 2011; 9 (9): e1001150 DOI: 10.1371/journal.pbio.1001150. Fruit bats find their way around caves and find fruit in trees using echolocation, i.e. making clicking sounds with their voice boxes and listening for the echoes reflected off an object. Scientists have wondered how they used this to navigate through complex environments like forests. Nachum Ulanovsky of the Weizmann Institute, Israel, and Cynthia Moss of the University of Maryland, studied Egyptian fruit bats (Rousettus aegyptiacus) to find how they do this. They trained the bats to find a plastic sphere similar in size to a mango, which they hid in different places in a dark room, while they recorded the sounds produced by the bats with an array of 20 microphones. In some experiments the researchers also placed obstacles in the room so that it was more like flying through a forest. In these experiments the bats in order to get to the target, had to fly through a narrow corridor made by two nets held up by four poles. The experimenters varied the size and orientation of the corridor. As expected the bats sent out sound clicks over a fan shaped area ahead of them, but the researchers found the bats could alter the width of the sonar beam. When flying through the obstacle filled room the bats covered three times as much area with each pair of clicks as they did when there were no obstacles. They also increased the volume and intensity of the sounds. The wide field of view enabled them to keep track of the nets and poles as well as the target object. Ulanovsky explained: “This is the first report, in any sensory system, of an active increase in field-of-view in response to changes in environmental complexity”. He went on to suggest “active sensing of space by animals can be much more sophisticated than previously thought” and there should be “a re-examination of current theories of spatial orientation and perception”.


Editorial Comment: Bat sonar can only work when the ability to produce high pitched sounds, and hear high pitched sounds is combined with an inbuilt brain circuitry which can interpret the echoes as trees, or rock face or fruit or, in this case, plastic spheres. There is no doubt about it – the Creator God is a sonic genius, and bats are just one evidence of it. It is logical to state that all parts of the bats’ sonar system, including the ability to adjust the system to gain the most useful information, was designed and built by the Creator of the whole bat, complete with all its sensory systems and the ability to fly. So in the light of the above data, the one current theory that most needs re-examining is the idea that bat sonar originated by naturalistic evolution, and yes it is illogical to use chance random evolution to try to explain the origin of bat sonar. (Ref. mammals, navigation, bio-sonar)

Evidence News 7 December 2011