Melvyn Bragg and guests discuss how some bats, dolphins and other animals emit sounds at high frequencies to explore their environments, rather than sight. This was such an unlikely possibility, to natural historians from C18th onwards, that discoveries were met with disbelief even into the C20th; it was assumed that bats found their way in the dark by touch. Not all bats use echolocation, but those that do have a range of frequencies for different purposes and techniques for preventing themselves becoming deafened by their own sounds. Some prey have evolved ways of detecting when bats are emitting high frequencies in their direction, and some fish have adapted to detect the sounds dolphins use to find them.
Kate Jones
Professor of Ecology and Biodiversity at University College London
Gareth Jones
Professor of Biological Sciences at the University of Bristol
Dean Waters
Lecturer in the Environment Department at the University of York
Producer: Simon Tillotson.
United States


00:00:00this is the BBC this poll cost is supported by advertising outside the U. K. this is the BBC thanks for downloading this episode it in on time there's a reading list to go with it on our website and you can get news about our programs if you follow
00:00:17us on Twitter at the BBC in our time I hope you enjoy the programs hello if you could hear bats flying at night they would definitely they make louder sounds in almost any animal equivalent to a pneumatic drill or jet engine but at higher frequencies then we can
00:00:33detect thankfully many about shoes echoes from the sounds they make to let Kate that prey and avoid obstacles in the dock don't crimson to swells they to do that and the techniques being found on being found in more and more animals which are sensitive it's been likened to
00:00:49hearing in color not sure historians about suspicions that but to a echo locating since the eighteenth century but it wasn't so far but it was so far outside human experience that even into the twentieth century anyone advancing that there had to contend with ridicule from other scientists women
00:01:05to discuss echo location all Kate Jones professor B. collagen biodiversity universe college University College London Gareth Jones professor of biological sciences at the university of Bristol and being washes lecturer and environmental department at the university of your P. waters who first suggested the banks might have this skill
00:01:26mobile for that we have to go back to to seventeen ninety three an Italian priest Lazzaro Spallanzani and Spallanzani he had a pet owl which predates Harry potter by some considerable margin but and sounds on notice that when the candles binaries al just blended into the walls as
00:01:44well owls probably need vision and lights to be able to navigate at night but you also observe bats and he found that the bats even in complete darkness could still or in tight and navigate so so interested in how high basket around without using vision eagles also experiments
00:02:03by by covering up their eyes with the with little cloths and so on but still found they could find their way around navigate very accurately that would come back having had a good meal off to after being out at night so I went to the initial spirit of
00:02:16experimentation he did something which is rather gruesome so so if anybody's pass of a sensitive disposition lightly might want to cut it listenable underway but he blinded some bats and he found that the bat switch what will blind could still navigate and find a way around so he
00:02:33knew then that the vision wasn't necessary for bats the same time a chap in Geneva cool shows you mean was also done some experiments but he was plugging the as of bats with with wax and he found that if you plug about is then it just bumped into
00:02:48things so Jerry knew then that it was the is the world when necessary for for bats to navigate Spallanzani originally was was very skeptical once it hurt but she rings findings and but he repeated experiments have found you plug Pattison they called to account not a case of
00:03:05hearing was necessary so that these two men were on the track there on the trial and it took about only into until the nineteen thirties for this to be taken of it anywhere with that person's like ourselves who take seriously what it what it did I I at
00:03:18the famous %HESITATION French soldiers key that was very skeptical of these experiments and so nothing really happened for about a hundred and twenty eight years or so and Hamilton Hartridge was a physiologist at Cambridge published a paper suggesting that was high frequency sounds that the bats were using
00:03:34and there was a a graduate student at Harvard cool Donna Griffin he was working about migration and he had some bats and he heard that a scientist physicist who GW passing developed a microphone which could which could detect ultrasonics so Griffin took his bat so long to to
00:03:51pieces of poetry in front of the microphones which is a little salt crystals that the produce electric current when they vibrated by sound and we didn't perhaps a minute all of sudden these these little traces were coming out from the oscilloscope you could hear the pulse is because
00:04:06they're using a technique called Petra dining which is about a foot for radar and so is must be a fantastic Eureka moment that within the space of a minute this hundred and thirty year old mystery consult the bats use ultrasound for navigating and can you just explain what
00:04:21ultrasound is the ultrasound %HESITATION comply conventions anything above all normal range of hearing which is what eighteen kilohertz if you're a young female and haven't been to too many night clubs which I'm not sure really complies to many of us here and but that so it's it's ultrasonics
00:04:37above the range of hearing and one about to get up to well I produce very high intensity ultrasonic pulses when I marry high very high is up to about two hundred kilohertz normally bouts with Dave range of application calls but from about eighteen kilohertz up to about two
00:04:54hundred kilohertz with two hundred thousand cycles per second so it's it's much high frequency then we can have much higher frequency than dogs and cats can hear as well and this is key to their success is finding things can be pining that pride and so what allows them
00:05:08to to exploit nocturnal insects which is a fairly unique %HESITATION food supplies of flight attendants sex because nothing really help that can exploit the civilized into two it took to multiply into and propagate and evolve and and occupy pretty much every constantly with apart from Antarctica thank you
00:05:27very much Gareth Jones can you explain come we just talk a little bit more about high frequency sounds and one week on him right okay so arm as the mentioned are hearing is restricted to %HESITATION round about eighteen to twenty kilohertz there's no real need for us to
00:05:44hear really high frequencies was if you're backed %HESITATION well first for your flying around at night you need to work out where hope school saw many bass you have to detect very very small targets things like tiny insects to detect school targets you have to produce very high
00:06:02frequency sound frequencies with very very short wave lengths these are the only as to explain a bit more the high frequency sound is armed consists of the way how is the way I tried a case so %HESITATION if you just think of %HESITATION a series of peaks and
00:06:17troughs forming waves if you think think think in terms of the stone being thrown into water for instance the room the waves that emanate from less than going into the water they're similar waves going on in a when we speak of moments of time talking to you their
00:06:33sound waves propagating through the room but these past me to produce really really high frequency sounds we need to do this because they need to get echoes from very small targets hi high frequencies are really necessary to get the strong echoes back so one of the reasons why
00:06:53bats use ultrasounds to get strong echoes from small targets however felt that they were costs as well associated with producing these very high frequencies all signs of spreads spherically away from a sound source and arm it spreads %HESITATION according to the square of the distance from the source
00:07:15of some of the tenants very very rapidly ultrasound very high frequencies the short wave lengths absorbed it's it's absorbed by particles in the atmosphere soldiers are not only arm falls away and intensity because of this so called spiracle spreading which applies to all sound frequencies it's also is
00:07:36subject to atmospheric attenuation so the really high frequencies do not travel very far to the frequencies about to use tend to be typically in the range between about twenty and sixty helped kill such a lot of my hearing out of hearing range Sir there were few bat species
00:07:53that occur Kate one particular case run about eighty kilohertz we can hear it tick tick ticking as it flies in Mediterranean habitats for instance this one about species that goes as high as two hundred and twelve kilohertz because of the needs to use high frequencies to detect small
00:08:10targets the costs of the sounds not travelling very very fall at high frequencies this is sort of window of ideal frequencies bats tend to use what do we need to know about the speed of sound to help us understand what about today a case of the speed of
00:08:28sound arm is really important sabbats really %HESITATION have to work at the positions of all Jex around them and to do this they can look at how far targets away he's away from them by measuring the time delay between producing a sound in receiving the actors to the
00:08:46speed of sound is pretty constant typically it's round about three hundred and forty meters a second it varies a little bit according to temperature according to humidity but this this time delay this critical in how about sort of translates a time delay into the distance an object is
00:09:05away so much making a very strong European mathematical calculation mecha comes back it has to work on the time is taken to go and to come back to work on divide that by two and then go in the direction George moving very quickly inside it's fine yes I
00:09:22mean the sort of neural processing scarring on must be happening very very quickly it's not just the distance to the target about has to work out hive and it also needs to work out with a classic where the object is in the vertical plane and where it is
00:09:36in the horizontal plane does it in the physical plane by having a little structure next year called the tragus and they're sort of interference patterns of sounds that created by the tragus and scientists have shown that if you take down the tragus about the possibility to work out
00:09:54where %HESITATION a target is in vertical play diminishes and then in the horizontal plane boxes using intensity differences from one year to the other yes service these these three features target range vertical position and the azimuth the horizontal position of the target about seven different mechanisms to working
00:10:16out these are these positions Kate Jones we go on with what they can detect so we we know how they're doing it you know the speed at which they're doing it where we still it is already from an as yet it's quite a lot you don't know who
00:10:32what you do now is via the things I can detect can you just tell listeners what they can pick up yes so you I mean as Stan and Gareth of sad and they they try to detect localize and and find out objects of the ease of navigation close
00:10:50everything pranks a huge proportion of of about species eat insects say they're trying to find these quite small insects in the pitch dark say they use frequency a range of different frequencies to find these insects I went about starting to find insects they will stop the series of
00:11:11pulses say these third it might cam tweet say they'll be right like in this set is such a cool site box will add figure out where these insects are into that kind of searching around in space and then when they heard a man on the talk and I
00:11:30find myself that'll speed up there race that that making these pulses they get much more information about the environment one not because I hate that thing is moving away or saving downers taking evasive action it needs a lot more information about where this object is so will speed
00:11:48up its cool right service style going and then it will end with the what's called a terminal buzz she's like someone blowing across this he will try and fail find of the insect and catch it say busy his Karasev this huge variation and types of coals and frequencies
00:12:09that they use and it's all down to this problem with frequencies light frequencies died high frequencies don't travel very full and then say that if you want to see add quite fall you need low frequency say think about an elephant rumbles say they can half miles because it's
00:12:29a lie infrasonic coal but with high frequency it doesn't travel very far tools so it would be a few meters that nice suit the the problem is you you've got to at trade off between saying fall and sing in detail utopia interviews with seeing several times how does
00:12:49about CN's onka and then it just it from from the nursery what they can they know that this is a very little music but they also know it's furry then no but they know they have any knowledge or information about it before they attempt to eighties yes I
00:13:06am how does this massive estimation common at that speed and went on a small fee wavelength of sound safe the high frequencies about short wave wincing short peaks and troughs between the the different cycles say if you can imagine like a wave coming towards you as I'm speaking
00:13:22to you if you've got high wave a high frequency for these very short wave lengths say if I may I have this wave coming towards you than the chances of me hitting a really tiny object or fairy Ole antenna night a much higher because you've got such a
00:13:39high frequency and so you get this bounce back of of all this fine detail so it's like your trying to see with sound with this really short wavelength of coal but the problem is you can't see very far so evenly into ever cross yvolution time bass of try
00:13:59to optimize that cools for the environment that Iran and they pray that they eat say for example backs which have high frequencies that are in trouble if I fall say they make them really loud so that they can kind of get them across they add so this means
00:14:18as you said in your introduction the facts a really really really loud as long as I mean I should imagine any on as we would abounds on you could win if I could hear it now would be as I was in your mind to grow lately about it
00:14:32some some one by in them and South America has been recorded a hundred and sixty decibels thus twenty decibels higher than a rock concert and fifteen decibels higher than all pain threshold sages one but yeah savings how do they do that the I mean they want to move
00:14:54we're gonna come we are sending a come to him thank you very much for a lot the next few days how do they make the sounds they make sense in the same way that we do I'm so they have vocal chords any difference really is the not vocal
00:15:07chords all that and much stronger more robust than ours but there were a couple kind of special properties so if you much into the pot smoking because if you want a kettle drum with a slit down the center and I am so that you have to do vocals
00:15:21on the site and if you pull at that time I kept from me under the slit willing clothes and all the battles and compresses it's the avenues longs and compresses it to the point almost to blood pressure so the bat is almost switching off the blood supply to
00:15:36us yet lungs because the pressure is so holy what then does is then releases the vocal chords and I contract under elastic energy the vocal cords open and they start to vibrate and because its high tension the beginning very high frequency that comes out if you choose a
00:15:52guitar string the tight the township becomes a high frequency but I say relax on the elastic recoil the frequency then becomes law soso bats produces signals not offer a Holly and ends up very light was I was a sound and but the other side of city really interesting
00:16:11adaptations to have special muscles retention via the vocal cords out there about a hundred times faster than any human muscles if either about a hundred times false Infosys mammalian muscles you have to go to invertebrates with some snakes to have muscles which all of that focused on the
00:16:28need to be that falls because these bouts producing signals ten times a second when they go as Kate said into approach in such families you can be up to two hundred calls per second so they have to retention his vocal cords two hundred times you know to get
00:16:42the signals are a must be the most exhausting sound don't do they get help from the rest of the tiny primes with what John bones and all the rest of that that they do I mean essentially that they lucky because like echo location for free as as as
00:16:55case of this is incredible that enormous amount of energy that comes out that producing a hundred and twenty hundred forty decibels of Kohl's ten times a second eight hours a night enormous amounts of metabolic energy but they get it for free because the the lungs the muscles to
00:17:12contract the lungs are coupled to the flight muscles so as the bass raise their wings on the up stroke at the the muscles compress the lungs and the animal exiles and produces a second occasion cool so one wing point eight one application cool so like a couple two
00:17:29mechanisms together this is an obvious question I like asking obvious questions why don't they deafened themselves okay there's a couple ways the best thing to death in themselves couple of mechanisms involved I one of them involves the middle ear muscles so arm the little bones in the middle
00:17:50here %HESITATION I think it's the the Hammond the stirrup essentially have muscles attached to them when these muscles contract from the bats come essentially almost become staff wallet schooling so %HESITATION one one of the really important things for bats as well is very the closer they get to
00:18:09targets the more they have to shorten the cool so the imagine you're getting closer and closer to an object the sound is coming back faster and faster so do you really want to hear this faint very very faint echoes with the coming back so I'm you need to
00:18:25reactivate your hearing to hear these faint echoes from close objects so you have is to send receive system a bit like occurs in radar actually so of the sound is sent out ability of muscles contract the **** definite cells were these really ready intense sounds and then they
00:18:42have a listening to the actors come back in plus they come closer and closer to objects on the sounds have to get shorter and shorter so that the outs going sound which is really really intense doesn't overlap with very very faint echo it's returning so what do they
00:19:01do do they just do not read that they displace inanimate something I think it's more to do with this the these muscles attaching to them tiny bones in in the middle yet is is the mechanism by which the self deafening on this voted on a horseshoe bat stood
00:19:16in a different way almond maybe we'll talk about that when there are thousands of nations we haven't done enough but it has rock the whole situation because yes I mean school not so they don't definitely zones in and then move them them moving in on how we think
00:19:32it's not didn't I didn't quite get what you mean by CD old on what they see when they see an out of the city you're going to tell us what they see and if you don't think about what version really is it's you generate a map inside you'll
00:19:47you'll ought to treat so your visual cortex and get the two mixed up now because I listen to the same the visual cortex you generate a map where everything is so you can reach out you can touch something because you've seen it you touch map is the same
00:19:58it's a map if you touch something you know whether objectivity which for cross water at night you know where it is the only treat map is this exactly the same so bats build up a map but rather than using vision or touch they they use the old presents
00:20:11as they build up a picture of echo delays and high big objects all within that that old tree field so they just generate a map picture inside the heads okay so there's a really famous philosophical essay by Thomas Nagel cool what is it like to be about I'm
00:20:31Nagle was essentially interested in you know the question can we ever get our heads sought the head of another human being Tom but is an extreme example of trying to work out what it must be like to be something else he chose a basketball bats were really really
00:20:46alien creatures and I'm I'm not sure we will have a you know be able to understand pick to the world as a bat sees it but there are some things that we can get some ideas about how much in a single picture of buildings costs of stroboscopic way
00:21:01so they're getting these pulses coming back maybe ten times a second builds up a picture of the world around them perhaps in the way that we see stroboscopic lights to the disco something similar as well so I think we can get you know some sort of picture of
00:21:19how about seeing the world but getting ourselves inside the heads of the bathroom picturing exactly how they process things how they see textural detail and everything that's a real challenge Kate occasions so weak on here about them hustle of the praying it better in a better position than
00:21:39we are is is is is stealth bomber homes in all day thinking whoops not going to go boating action all but about six votes around says sixty to ninety five any music and say they evolve later than a lot of that pride that say the heat seven six
00:21:57vote much Shelia say to any one of the reasons for that massive success in the mating kingdom is that life top ten to unsuspecting prey say the vast majority of of private Patsy don't hate them and makes the captain and did a great job but there are some
00:22:16great job the unions are you know because I'm a demolition unit you know you're a midnight snack and say there are few insects that have developed these anti backed devices say %HESITATION at a lot of these are kind of backed detecting is save up and it hearing and
00:22:44insects is involved in at least six different orders of insects and will say at within at butterflies moths production is also involved independent name around six times so it's a really %HESITATION it adaptation to a listing for bass we think for the summons for some insight grapes a
00:23:06there was a kind of co opted a fast so that they could you could hear movement anyway %HESITATION they hit noises anyway in some of these organs on them on my body but %HESITATION in laptop should we think they've involved these back herring is when they take avoiding
00:23:23action of time can you tell us about the time tomorrow since on Jack yes say so you say some bass when they when they hit and these %HESITATION ultrasonic coals that very sensitive to particular types of cool so too is about that such face cool be full surface
00:23:41if I'm off with these areas his such face close them they might not be about all this because the box far away it hasn't seen them yet but when it starts to speed up they stop panicking and and think I can't quite say completed avoid that you know
00:23:57defensive action so they can many that I really meaningful so they can drop out the sky old or take different turns and twists so that behave radioactive place a bet that the bats date see them and then some office of even if all of this ability as he
00:24:13said this type of off to make clicks said that he are actually producing sound and we we don't exactly know what they at function of this is but that type of Mosul side of poisonous say that the Bucks county insert could be a warning or it could be
00:24:32that it's just awful response safe in ninety five wild what's this you know Connie that or it could be that the jamming the jamming state they get really confused the like I don't know why this thing is that I was doing the cover on the talent to distinguish
00:24:49in ninety but you tend not go to the back of the the second sort of finish up now and then at fascicle these counts images so it's like an arms race hello so you got to go and that was some evidence that backs can change the frequencies so
00:25:08they get a much higher any always talked about lives of high frequency cools at that time travel very far but some have gone higher to avoid maths hearing them all I would say it is old by getting to self made in there that I may have to location
00:25:23cools who works out those crazy yes and if you're in Texas and twenty million come out of the cave at the same time it Mr anyway never mind it's not that to what me must think about it but it's very difficult to think about really wanted to get
00:25:37in the game discuss I that this is such a nice experiment that you can do at home it is you can demonstrate you'll you'll most defense mechanisms and he only needs a bunch of keys keys produce a lot of ultra sound when you jangled and you if you
00:25:50have a an outside lights that you have months gathering my particular this Tommy it works really well is is you sneak up on your mouth with a bunch of keys at very very carefully and then you take your keys in the jungle of very violently and what you'll
00:26:02see the moth doing is it will do a whole series of loops and dived my fly for the opposite direction and sometimes even just drop to the ground and hide off from the cross because far that concerned over it simply is is those keys produce enough Optimus had
00:26:14just like a bat Crikey it's time to get out of here so you can actually see this this co evolution elms rice in action home as we have a multi invasion underlying see quite a few people reaching well I keys rushing up to the headstone if if Martha
00:26:28not your thinking your sketches just take a bunch of case will be fine and you can say it's not just that insects that can hear about so respond to this the key stick attack but plants no can hear box but they also respond to bats acoustic coal say
00:26:48%HESITATION some bats pollinate and %HESITATION aspect seeds of lots of different fonts important harnesses and some plants can the have adopted that leads to bad parabolic dish say that they can advertise ready to back say come head as the free snack any component my plants as well so
00:27:10that this like a box beat him so I think is not seen credible we'll just we'll slice it involves the collection but this is this is this is so intent on not on the list I have a lot of you don't mind can we guys can you tell
00:27:23us about the horseshoe bay he hosts about surmising I mean I'm an evolutionary biologist some interesting adaptation and for me the application cools cools you pass when the best examples of adaptation of that too since we back to that it was designed to make a move when he's
00:27:41on occasion and we've been tell them being I've all but ninety million years or so the adapted over the long time or just in the last fifteen minutes no more we don't come to think of it well look the fossil record of bats is not great there's a
00:27:54big argument about %HESITATION do you know whether the first fossel bass were capable of application one office it is one of the big sort of questions and application research at the moment but some of them almost certainly being able to stream modifications of the time of the Cole's
00:28:11okay back to the whole issue about so the whole shoot back cool the whole she but cool lost about fifty milliseconds fifty five thousandths of a second is absolutely tone cool doesn't wait wavering frequency tool this gives the server application has to work in three ways first of
00:28:29all you have to %HESITATION detected targets you have to then localize the target and then you can classify the talk at these long long coals very very good at detecting targets also very good at classifying target Sir something like must be too much fly flapping its wings it's
00:28:48safe several hundred times per second a beetle might be flapping its wings perhaps four times second so from the little acoustic violence as we call them a come back during these long Coles response can tell I'm a skater from the people that can classify I pray types and
00:29:06they can choose their dinner accordingly I that's very very smart not only to have these abilities ability to classify targets they also put little sweeps at the end of the cool and this allows them to localize targets as well they also do something remarkable called doppler shift compensation
00:29:24to these very long constant frequency coals of very susceptible to doctor shifts of the classic example of doppler shift sees when you're standing on the road in central London and ambulance comes towards you on the sound waves get compressed the frequency goes up as the ambulance moves away
00:29:42Soundwave stretch out on the frequency goes down these long calls a very very susceptible to doppler shifts to what the whole she bats doing is very low at the frequency of the cool from cold cool in relation to the speed that they fly so the compensating for the
00:30:01doppler shifts incurred by the flight speed this means that the cool only send out in the echo that they receive on different frequencies so they don't have this problem of self definitely separating the pulse and the echo in frequency rather than in time to host your bathroom amazing
00:30:20in that they could produce these calls is redacted old these functions of application detection classification localization and they can do it by this remarkable doppler shift compensation is a fantastic example of adaptation way of talking and they're gonna take over questions unit Kate Kate Connolly them can we
00:30:42distinguish bonds by the sound I make when I'm into talk of distress calls you talk of a desperate is among the nine childhood and that sort of thing so you can distinguish them in as well as yes say who I'm with IV over the last few years we've
00:30:56developed time not serve as technology senses to head back say that neither above makes them Buffy can say so we have these little devices which we can now use to transform not sound down lower in frequency so we can hand side %HESITATION one of the ways that %HESITATION
00:31:17we try to tell species apart like humans tries tells fees for is by listening to these calls on the census on them back schools all are really different from bad cool site but cools alike out here I am I look fantastic that you want to comment with me
00:31:37that is not so kind of you know her cool Abed makes all gets off my territory I'm back who's a very functional so bad how to find their way around so that they can be very very very tricky they they change they have different accents across space add
00:31:55a geographic space and they've also go out and differences in sex is so that it's very difficult to tell and as a species from its coal in what is unknown some boats don't use accreditation all know that this place is two groups with two about surviving the order
00:32:15corrupt terror which means current meaning hand terra meaning when I see a chiropractor and terrorists and terrorist cells we have to wait to supporters have the micro car up to rule the small hand wings and make a corrupt terror which the big happenings under in the we are
00:32:31the big ones for the thought that the make a character don't explicated woodlands with any was one group that kite kites which is the the resistance which is awesome cave Egyptian fruit bats and in case my produces what tongue click because of I'm but the microscope terra and
00:32:49they they all act like I all kinda kinda Kate but some of them choose not to because he's the stealth bats to these the ones are overcoming the %HESITATION the insect defense mechanisms so it because inside skillet insects can have bats if you switch off your application will
00:33:05make it very very low intensity at the very end is you inside com detect use a week so you can then so can you can you can catch you can listen by passive hearing so some bat circle really big is that just listen to the passive signs that
00:33:19the insect to making either in flight fourth according around on the ground so that I can listen Ralph of an iconic high enough and doesn't let his pride yeah carriage rooms which abled first clientele application rack the chicken intact this is a game is not resolved at the
00:33:40moment so my feeling is likely the application the phone before flight partly because if you're flying around at night time you need explication to find out where hope checks all on those we've forgotten the business it's it's so as not to bump into things on yes that's right
00:33:59that's right so so %HESITATION yes obstacle avoidance is really really important so that that there is a debate going on so there is a false hope that %HESITATION only connects receipts cold it dates to around about fifty three million years ago and people have looked at the structure
00:34:14the call here in the year arm office fo'c'sle and foggy that actually the structure of the caucus suggests that he did not act locate faithful flight temple before application however scientists have also looked at other bones %HESITATION near the high alert apparatus in the throat and some of
00:34:34these bands are characteristic of allocating bats today from people I see this but did to explicate off to rule this problem this is a pancake for school it's really flat so the structures can get distorted in a minute I'm my my my feeling is probably application for us
00:34:52but also as the mentioned earlier there is this coupling between flapping wings and producing sound sub bass concentric produce application sounds with cheap at no cost when they're flying no energy cost and no energy costs of this could mean that you have a strong selective pressure for flights
00:35:10and application to a vote in tandem together at the same time is also really fascinating discovery that happened last year people find %HESITATION pygmy door mass in Vietnam produces sounds very much like the application cools baths it's got he is very much like explicating bats the scientists have
00:35:30not conclusively show Mister echo Kate's but the structure of the Cole's destruction for years suggests this could be a terrestrial explicating species is not related to pass not an ancestor but it does show that you know application can be effective on the ground said as it slides come
00:35:48in with their is a bit of controversy around this mega mega back to my car back taxonomy said that team is saying and and Gareth has been talk about the evolution of I can location safe with megabytes they haven't got this ability to communicate with Mike about this
00:36:06they do have it but new %HESITATION genetic evidence this is a little bit controversial but I'm new genetic evidence is saying that the the mac about self family within they even issue trade off the microphone so there isn't such a thing as mac about so much about several
00:36:23facts which is gonna fascinating implication for the violation of echo cations so excited that involved once at the base of this group and then lost in the megabytes or it's evolved independently twice so we there is a really open questions as absolutely fascinating area that in an old
00:36:46car up to legis agree on I'm going going about the evolution occasions is is possible evolve even more than twice with you look what with the whole she bats now replaced with with megabytes and you also have this %HESITATION crimes unit crystal Longhi I which is a fun
00:37:03test a long line for the world's smallest backed and that's also within that group is on the different type of application so you must be looking explication styles or different types of tools arrangements on the whole she busts of allowing multiple times within this lineage you're going to
00:37:20the well I I think I would just add the hot pink behind my understanding is the evidence of the moment is his favorite a single origin and and loss in the mega corruptions partly because people have looked at the developmental history of %HESITATION of years structures in these
00:37:37animals may find similar developmental patents in the Norfolk locating baths does the necklace hating pass the argument has been made base is support for and single origin and subsequent loss which is actually the most possum and it's the most likely explanation in my mind I think applications such
00:37:56as sophisticated adaptation especially the way bass uses multiple origins is perhaps unlikely is it the cages how about having an effect on the way in six to developing on the name on the look out of a sixty seventy million years and they've developed they have evolved to meet
00:38:15the threat absolutely have you name it you see this this box moth at K. evolution as a a really good example of that of a partisan pry arms race so it's is usually held up as a really interesting example of how even nation over time is adopted the
00:38:34moths to the presence of bats so even in and not just the is but behave adaptations say some moths have become a bit more diagonal because they're trying to avoid bad so they try to shift different seasons of the come out before the box come out of hibernation
00:38:50or off to the backs of going back into hibernation said he was a really incredible and at the arms race going on and adaptations back and forth I mean what what areas in this research has been quite a lot on this this isn't your going going three for
00:39:09the Kaiser I need you think all may not known men and run the morning a perhaps even not knowable well I think that's the big question for me is is a big mismatch between these fantastically elegant behavioral experiments you condone bats where you can sit about on a
00:39:26platform you can train its listens to different lights because you you great she would choose the differences between two calls to producing two dot com tell one or the other from one to the other side and then the walk toward the light speaker thinks producing a school which
00:39:40is slightly lighter ones aside different structure so that telling us they can resolve incredible detail but from what we understand about the physiology the why the animals process or the transformation we know that's not possible they shouldn't be able to do things account that they do but they
00:39:56do so those two things either this something extra in the painful experiments that we don't understand about soliciting different cues and that's a very clever so we might be trained to listen to different things so what we interpret the experiments during the past my note all the something
00:40:12extra physiology that we don't yet understand I suspect it's not doing something in the physiology that we don't understand what it is yet only taking the I don't I don't we take people like you're taking that on all your your fellow academics in different disciplines and saying okay
00:40:26we will try to use this or finds out how it applies to other things including ourselves right arm so I mean face a huge amount of research and so now and right hand signals derived bison radar engineers resemble those of bats very very closely except bass in full
00:40:44from over fifty million years ago probably about to head in this race between right now or in baths arm I think given them Minnich's size their abilities fly around very quickly there adaptations have not necessarily that there are groups in America trying to do biomimetics studies to try
00:41:02to mimic %HESITATION explicating Bastrop think blacks are remarkable in these adaptations yeah what would you really like in about basketball in this program I'm really interested in how to track baths %HESITATION over time and space age when the sun that populations in the conservation and I am frustrated
00:41:23by the fact of how little we know about communication tools and we need to build up back to libraries in our understanding of cools to be able to build better methods to identify by individual that similar to come back in the previous terminal will mentor I'm very sorry
00:41:40and that we didn't get round to dolphins and two wells but that's another time another another program next week we will discuss the Mexican American war of eighteen forty six to eighteen forty eight and how it affects ago with topics territory thank you very much for listening thanks
00:41:55to Kate Jones cartoons and D. waters and the in all time put costs get some extra time now with a few minutes of bonus material for Melvin and his gas we only got about this and make it much micro thing it is is that it's a great introduction
00:42:11to the younger crowd dress you enter a cover up whatever whatever those names idea because it leads very neatly into into understanding about how we were traditionally classified organisms based on the morphology of life history strategies verses the molecular genetics and molecular genetics always throw some spinous into
00:42:34work so we don't see the molecular genetics is is not without problems and folks interpretations but one question I didn't ask %HESITATION as a how can they tell that sound twenty million come but side of the cave in Texas Hockenheimring button Jennings distinguishes about number nineteen hundred I
00:42:54minimize their own secular sound through Bucks but been to to brighten type in Texas near the twenty million Mexican free tailed bats come out and if you try to make a recording is just noise that you can't even make out individual calls is extraordinary but that's how this
00:43:09whole temporal expectation so when they produce the coal they have an expectation window when it cools going to come back so that you can change the gain in the road to true system so they can ignore anything until I get to the window whether expecting a signal to
00:43:25come back and not point that within run pop the guy Anderson for the remaining twenty million to yeah lies a bit crazy I mean look at how the money to do it wait while we sing all say that they recognize the wrinkles I'm not ready at another area
00:43:39which is credibly interesting that we don't matter anything about we think that they can recognize running voice I can recognize my voice that can be so why combats the that we think they probably can so light infant bats are left in this parking cave in a big mastering
00:43:54and little crush while big crash and they're back mums guy back and %HESITATION feet and then come back and falling there in pop say they can find their own path Poppin thousands of pops say at the beginning of this research we thought I was Tyson impossible it Feynman
00:44:12pop and we thought that they were alive I like feeding me where I live in nursing so they would just messing any pop that that was that made everybody was very excited about this whole idea of aliveness emails crazy idea and how did that evolve but actually they
00:44:26recognize the writing pop in and a whole bunch of cops amass they can do it I mean that's incredible isn't I mean for me that some of the big excited to really exciting areas to explore an application process of them of our one the use of little miniature
00:44:45devices that being fat fitted two baths team put these tiny tags on Pat's workout with a off from the GPS coordinates but also record their application cools service is giving us an unprecedented view of application behavior in the wild on these tiny animals are you get the tax
00:45:04back you can download their application because his life around and the other areas but it's really exciting for me is is molecular genetics from Tom what is it but what of the genes involved but make baths give basses amazing ability to replicate most amazing examples of convergent evolution
00:45:24at the gene level to whales and dolphins have involved hearing jeans on the th of undergoing similar mutations to birds and bats to cope with dealing with high frequency application calls so I think there are some really exciting new discoveries awaiting Senate I think you'll be we can
00:45:44about this idea that the application somehow it is difficult me full flight we know civil multiple times what funds climate treason check themselves out and lies to the list how it flies permanent difficult but some of the idea that the application sizzle highly cryo but but we will
00:46:00likely take to some extent we we perceive the spice arrives by the reflection of our own echoed so he put somebody into an echo chamber absorbs all sound run with a fantastic big one down south Hampton university is of science but with the console really disorientating experience because
00:46:16everything even the rustling of your closing you call pickup that because you have no idea how big the spices with you what kind of car rental you pick up the sounds of your own feet clean your clothes rustling you know how big that spices so all human beings
00:46:30who will echo cut some extent it's just kind of activity about doing actually until and processing it really quickly for me and the really exciting Satch is on doesn't disagree goth but I think it's on about how we interpret these a case about so leaking information about themselves
00:46:48into the farm all the time and we can use that to monitor that populations said that at we can start to build up and in a new technologies in the census so that they can go through all these recordings and pull out a different species of past how
00:47:05time if it's about that remote species is and also is a way of really engaging with the public as well because you can give them these to taxes and then the whole sky becomes a life with facts because you can't hear them normally and then you get these
00:47:19the taxes and then it's a an amazing experience of people they just flying over their heads and I didn't recognize didn't notice and it's like a whole New World of an ecology in nature and conservation it's tonight about I think that's really powerful for me it's just impossible
00:47:38punk's really about these echo echo location humans because it is remarkable and people of recently analyzed the sound clicks explicating humans make several visually impaired people applicators some very famous people cockle Daniel cation the the in in in America who rides spike's arm by using echolocation etcetera and
00:48:02the cliques that these humans producing around about three milliseconds long which is about the same duration as the cold baths sometimes it much lower in frequency survey techniques have most energy between two and four kilohertz but they can still be used to build up Palmer remarkable picture of
00:48:22surroundings but the humans using these cliques are actually using the visual cortex in the brain which we use for understanding the world by sight to process the echoes in the past since the older pre cortex has become really really specialized for processing occurs severities quite remarkable differences between
00:48:41how humans are doing it and how about sitting it but explicating humans amazing and this is being developed by buying them by people being making things are turning to actually basically the cutting of the change tournament about true yeah yeah that's the only so going back to its
00:48:58Thomas novels aside what is it like to be about so so is it is a couple things you can do you can you can use so not technology I mean we all use on a technology was not every car was gone reversing alarms on it and as you
00:49:11you can towards an object Europe you'll along with it it gets gets louder and faster so that's just not paying %HESITATION distance onto of signed frequency you can develop devices for helping people with visual impairments that that many years ago we we helped develop a case in which
00:49:29send ultrasonic pulses picked up those pulses and relate those to a little vibrating button on the handle of the wood five rifles to the classical two objects but also I would be looking at ways of of taking radar imagery and balls and sing it visually is mapping out
00:49:47onto you'll you'll order tree spice so that this idea about visual maps an old tree maps his role in having a radar image which is on the screen is you take that right all signals and you turn into some non you listen in three dimensional virtual jam space
00:50:01where objects are around you so it's incredibly first so we can learn an awful lot from from high paths using concussion well the producers straining at the bit to come in and give us some information extra futile coffee coffee please please let me come in our time with
00:50:17Melvin Bragg is produced by Simon tell it's in a magic carpet to world events and wickedly wonderful places with inquisitive knowledgeable guides correspondents who witness invasions the full of governments would would also like to tell you what it's like getting a tattoo by mistake in India or buying
00:50:37a tee shirt to the sound of anti aircraft fire in Libya from our own correspondent has never failed to delight and surprise me there's always something new to learn there's also a depth of experience when someone who spent years reporting a country has to pack their bags and
00:50:54move on and has a wealth of memories not only of interviewing the country's president but of desperately huddling for decent jacket to wear for the occasion you'll find from our end correspondent with me Kate Adie wherever you usually get your part costs

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