Yossi Yovel has a fantasy: He wants to know what it is like to be a bat.
“It's what I try to understand every day,” said the young researcher. “One day I'd really like to build a small sonar that I can attach to my head, then close my eyes and start walking around.”
For the time being, Yovel, 33, has to settle for developing one of the world's most advanced laboratories for the study of bats. He will use the space allocated in the heart of Tel Aviv University's Garden for Zoological Research to raise a colony of fruit bats.
At night, the bats will be free to roam the city's skyline along with the almost 20,000 other squeaking winged mammals that live in colonies in the Tel Aviv area. All the while, Yovel will be monitoring them with attached microphones, video cameras and global positioning devices – "the smallest GPS in existence," he proudly declares.
“Nobody has access to such data today," he said. "Advances in miniaturization made the technology possible only recently."
Yovel, one of just a handful of bat experts in Israel, stresses that very little is known about the animals he studies even though they make up at least one fifth of all living mammals. He hopes his laboratory – which is being constructed among the zoo's ducks, peacocks, flamingos and gazelles – will help illuminate their shadowy inner world.
“There are many unknowns regarding bats' sonar capacities and how the brain allows these capacities, but we know even less about the complex web of social relations between them,” he said. “Some bats live in colonies of thousands of individuals where they stay for up to 40 years. We know very little about these complex cities. Do they fly together in certain groups? How do they transfer information to each other? Do different colonies have different accents when they communicate?”
Some of what we do know about bats is simply mind-boggling.
Can you tell you're one human hair's breadth away from me?
For starters, their famous sonar – which works by bouncing ultrasonic waves off objects – allows them to measure how far they are from an object to within 100 microns, roughly the thickness of a single human hair. It can also detect objects smaller than the sonar's wavelength.
“We have almost no clue how their brains do that,” said Yovel.
And try as they might, engineers have so far been unable to build a sound system that can recreate a bat's call.
“I spent €5,000 on a speaker 10 times bigger than a bat but 10 times weaker than a loud individual,” said Yovel.
Another engineering mystery is the ability of bats to fly in massive groups – sometimes containing thousands of individuals – without jamming each other's sonar.
“A bat needs to know which echoes return from his own calls and which return from another bat's calls," said Yovel. “Very soon, every car will have a radar device and they will have to deal with the exact same problem.”
Yovel plans to look at the brain mechanisms underlying this so-called echo-individuation ability, as well as bats' other poorly-understood talents, with the help of fMRI, a tool that is new to bat research. He will broadcast pre-recorded calls and echoes while mapping listening bats' neural activity, looking for signs that they are familiar with certain calls. Fortunately, fMRI is non-invasive and causes little stress to the animal, he says.
Excluding one paper published 13 years ago, "We are the first to scan the brains of waking bats in an attempt to get some answers," he said.
Yovel acknowledges that high-tech monitoring systems and fMRIS will not let him experience what bats do anytime soon. But he can imagine. Pointing to an image of a thick forest, he enthusiastically describes how a bat perceives the trees.
"You're receiving a thousand echoes using only two antennas – your ears – each one receiving a one-dimensional signal," he said. "And among the thousand echoes – while you're flying swiftly between the trees and trying not to hit any of them – you need to find one little moth giving away its existence with the flapping of its wings. This is a problem that no man-made machine has been able to solve. We just don't know how they do it."
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