Excellent article, pretty comprehensive: http://www.acoustics.hut.fi/u/mairas/pubs/echolocation_in_bats.pdf
Echo-location and flying Mammals
We’ve all seen bats flitting about in the night sky, or pouring in massive swarms out of a cave. Two remarkable things are:
1 They miss one another
2 They feed on insects which they can a. detect and b. intercept and c. catch.
But let’s say a few words about this incredible phenomenon.
How do they do it?
‘This sonar [of the bat] is a marvellous discriminator: in a bat–swarm, in cave or night air, a bat can know its own sound among thousands of mobile neighbours, detecting its own signals even if they are 2000 times fainter than background noises. It can “see” prey, such as a fruitfly, up to 100 feet away by echo location and catch four or five in a second. And this whole auditory system weighs a fraction of a gram! Ounce for ounce, watt for watt, it is millions of times more efficient and more sensitive than the radars and sonars contrived by man.”
That excellent description clearly shows the standard features of Design
1 Complexity: the structure of the echo-locating system is miniaturised to fit inside the small skull of a bat, whose brain probably weighs only a few grams (about 15g in many cases). Flight is another complex achievement. NO OTHER MAMMALS CAN FLY.
2 Specificity: the echolocating device is amazingly good at locating insects, obstacles and doubtless predators. The flight mechanism is specifically functional.
3 Information: Highly advanced information is employed as the following shows.
Evolution of the Bat
There is none evidenced.
The skeleton of the Eocene bat, 54 million years ago, shows no important differences to those of today’s bats. But remarkably, they show that development which indicates that the sonar apparatus was already in existence.
"Unfortunately, the fossils available only complicate matters. They do not represent transitional morphology between quadrupedal (four-footed) animals and flying bats, and they represent animals nearly as specialized as their modern relatives"
Thewissen, J. G. M., and S. K. Babcock (1992). The Origin of Flight in Bats, BioScience, May, v. 42 n. 5, pp. 340-345.
John Hill says almost the same thing:
"...all fossil bats, even the oldest, are clearly fully-developed bats and so they shed little light on the transition from their terrestrial ancestor"
Hill, John E., and James D. Smith (1984). Bats: A Natural History, University of Texas Press, Austin.
Complexity, specificity and excellence
“We now know that bats have a method of doing synthetic aperture sonar while flying that not only determines the distance and direction of all the objects in a scene, but also reconstructs one specific object's shape. What's really incredible is that they can do both simultaneously."
I might add, at quite some speed too.
"ONR [The Office of Naval Research] would like to get naval sonars, both in listening and in processing the return information, a bit more, well, bat-like," notes ONR's Harold Hawkins.
"We would like to emulate this capability for the quick, accurate detection and classification of buried mines," said Harold Hawkins, a program manager with the biosonar program at the Office of Naval Research in Arlington, Virginia.
In experiments, bats separately perceived and processed overlapping echo delays arriving as little as two microseconds - two millionths of a second - apart, an ability roughly three times keener than scientists had believed was possible in the mammals.
This fine-tuned capability, based in the bat's nervous system, allowed the animals to resolve echo-reflecting points on an object as close together as three-tenths of a millimeter, about the width of a pen line on paper. Such image resolution is significantly better than any man-made sonar, say the study authors.
"Using the same sounds as the bat, the best man-made sonar equipment can only process echo delays arriving five to 10 microseconds apart," said study leader James Simmons, professor of neuroscience in the Brown University School of Medicine. "The experiments showed that a bat's sonar resolved echoes that arrived two microseconds apart as easily and routinely as if there were 10 microseconds between them."
Use of Advanced Information
Knowledge of the laws governing sound travelling in air are clearly in evidence here. A bat emits a sound, which hits an object and is bounced back to the originator.
An article published in the Proceedings of the Royal Society on bat echolocation states:
Theory developed from acoustics and sonar engineering permits a strong predictive basis for understanding echolocation performance. Call features, such as frequency, bandwidth, duration and pulse interval are all related to ecological niche.'
We note firstly, that the bat knows that the sound IS going to be bounced back.
Secondly, the bat therefore has receptors which can receive the returning signals.
Thirdly, the bat has an onboard computer which calculates instantaneously how far away the object is,
Fourthly, the bat can calculate exceedingly accurately how far it will have moved itself by the time the signal returns. It can also calculate how far its prey will have moved, and its direction of movement. It can then compute a course to intercept the insect, and does so at the rate of 4/5 insects per minute.
Fifthly, it is navigating and flying at the same time. So the onboard computer has numerous functions to carry out simultaneously and additionally, including respiration, heartbeat, and other standard physiological duties.
Such calculations rival those in warplanes today, and just as those warplanes exhibit design, so does the bat. The bat, however can reproduce itself, and in this respect far supersedes any man-made contrivance.
The quotations below are further impressive technical features of bats' echo-location apparatus..
[One wonders how a bat ever found out about Doppler shifts, and then figured out how to use it, and then constructed the apparatus to use the information, and then fit all that into the genome, and into the walnut-sized brain that it has!]
'Quantitative measures were obtained from the vocal signals produced by echolocating bats (Eptesicus fuscus) that were trained to perform in two distinct perceptual tasks, echo delay and Doppler-shift discriminations. (!!!!!)
In both perceptual tasks, the bats learned to discriminate electronically manipulated playback signals of their own echolocation sounds, which simulated echoes from sonar targets. Both tasks utilized a single-channel electronic target simulator and tested the bat's in a two-alternative forced choice procedure. The results of this study demonstrate changes in the features of the FM bats' sonar sounds with echolocation task demands, lending support to the notion that this animal actively controls the echo information that guides its behavior.' ©2000 Acoustical Society of America.
'We used high speed stereo infra-red videography to study the three dimensional flight paths of the big brown bat, Eptesicus fuscus, as it chased erratically moving insects in a dark laboratory flight room. We quantified the bat's complex pursuit trajectories using a simple delay differential equation.
Our analysis of the pursuit trajectories suggests that bats use a constant absolute target direction strategy during pursuit. We show mathematically that, unlike CB [constant bearing], this approach minimizes the time it takes for a pursuer to intercept an unpredictably moving target.
Interestingly, the bat's behavior is similar to the interception strategy implemented in some guided missiles.'
Further comments on Bat evolution
The bat is a warm-blooded animal, bearing fur, and suckling its young on milk,[i]and flying[/i].
So in order to ‘explain’ their evolution, we have to suppose innumerable small steps, where we see the bat’s supposed ancestors busy climbing trees or rock faces, leaping from the tops, holding their fingers wide apart in the effort to fly while their superb echo-locating apparatus warns them of the swiftly and fatally approaching ground below. It’s no wonder there are so many fossils. They all broke their necks jumping off trees trying to fly.
I said ‘fingers’ – because a bat’s wing is supported between digits, unlike other winged animals. If you look at the skeleton of a pterodactyl, you will see the difference plainly – but the pterodactyl was a reptile. I repeat the impossibility: a bat is a flying mammal.
Such acoustic and aerodynamic engineering capability is far beyond the capacity of chance to generate.
So to summarise, Complexity, Specificity and use of very Advanced Information in the construction of a bat, conclusively show that it cannot have been produced by chance, but by A Designer.
We again note that instinct plays an enormous part in every aspect of the bat's natural history.
1 First, getting wings is an impossibility by any known evolutionary method.
2 Second, allowing that a pre-bat somehow DID evolve wings, then what would it do with them, since it didn't have a clue what they were about.
In fact, the bat would be at a very severe disadvantage - because IT HAD COMPLETELY LOST THE USE OF ITS FINGERS which had turned into wings.
3 But that's not all that was new. Suddenly, it had this sonar thing in its head. What to do with it, one wonders. Put an untrained ground crewman in the cockpit of a fighter aircraft which is equipped with the best echolocation apparatus ever invented, and send him out to shoot fast-flying hostiles.
He wouldn't get into the air, in the first place, and in the second wouldn't know how to use his fantastic new equipment.
Given a brain the size of a walnut or smaller in the microchiropteran bats, and given no training in flight or in the use of this unbelievably complex new equipment, I suggest that the new bat wouldn't last long.
The best equipment is useless without the instincts that power its use, and the best instincts are useless without the equipment to use.
BOTH HAD TO APPEAR AT THE SAME TIME - instantaneously, and perfectly functioning - there is absolutely NO WAY that 'gradual evolution' could have occurred.
But immensely advanced technology doesn't just happen. It is created by highly intelligent designers, with major amounts of equipment and materials at their disposal.
So how comes it that a bat 'developed', 'evolved' these fantastic designs which fill aeronautical engineers, acoustical engineers, and the military with such awe that they are even now trying to copy those designs.
And remember, the hardware is one thing - the software is another entirely. Those instincts represent the software - and no-one would dare say that the Windows program happened because there was an explosion in one of Bill Gates' factories.
No, it is obvious, even to someone as blind as a bat, that it was DESIGNED.
And design requires A DESIGNER.
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