Jim Moore: Darwin was driven by different things at different times, just like all of us. He was complex; he changed; he became more conservative generally speaking as he got older, but if you mean what drove Darwin to become an evolutionist, one has to say it has to be something as powerful as the forces that were ranged against evolutionists.

When Darwin is less than 30 years old, he comes back from travelling around the world – most of it was on land, not at sea – but he gets home, and within weeks, probably a few months, he’s become an evolutionist. Why does he do that? It’s a bad career move, and in our new book, Darwin’s Sacred Cause, Adrian Desmond and I say that that powerful drive that overcame the social stigma of being an evolutionist was Darwin’s radical belief in the unity of all life.

That common descent unites every species, the human race as well as all races of animals and plants, and that leads him to a powerful image that was part of the ideological foundations of the anti-slavery movement. The notion of a family tree of humanity for traditional Christians rooted in Adam and Eve as the father and mother of humankind. Darwin takes it a step further and unites everyone and says that it’s our arrogance to believe that we’re not related to animals; it’s the arrogance of the slaveholder lording over his slaves whom he likes to regard as another species.

Charles Darwin. Image: Jupiterimages Corporation.

Ben Valsler: This may well have been the driving force but still, it was a long time before he published. It was a long time before these ideas actually made it out there. Was there a tempering force as well that made him look for all the right evidence and made him make sure he could prove this before he would publish?

Jim: Darwin kept his thoughts to himself to begin with. He was in the process of becoming involved in the Royal Society as secretary of the Geological Society of London. He was welcomed to the inner sanctum of elite natural history. His sponsors were Cambridge clergymen, professors; he had a grant from the Whig Chancellor of the Exchequer, a huge amount of money to publish his Beagle research. He was a young man on the make. He was pushing all the right buttons, he was going all the right places, and yet he carried this terrible secret in his private notebooks. He needed a theory, and he began calling his speculations ‘my theory.’

That was his project, ‘my theory,’ and towards the end of 1838 he works out what we now call natural selection. By 1839, when he’s getting married and having children, he’s developed that, and he knows within three years – he leaves London, he takes shelter in the countryside – he knows he’s onto something really big. It’s going to change the course of the history of science if he can convince people.

Now, at that stage you don’t go public. You take every precaution that’s necessary to convince people beforehand that what you carry with you is true. It’s not disreputable; it’s the answer to the mystery of the diversity of life on earth.

So, he commits himself for the next 17 years, that’s sort of 20 years in all since he devises natural selection, to answering in advance every conceivable objection that the heavyweights of science in his day could bring against what he’s doing, and that leads him into huge research projects. And finally he gets around to putting pen to paper and he plans a huge book, maybe a half million words in three volumes which no one would read, and in the middle of all of that, you know, he gets outed by this guy named Wallace, everyone knows this story, Darwin has to condense his work into something which he entitles On the Origin of Species.

Ben: Do you think the pressure of having these other younger researchers formulating very, very similar theories based on very similar principles, Wallace was looking at series of islands much like Darwin had, do you think this forced him to make some concessions in his work?

Jim: Darwin was not aware that Wallace was working on a theory, until the paper arrived in June 1858. Darwin felt safe in his non-competitive ecological niche as a theoriser of evolution. He knew that all the other theorisers were discredited or spoke ill of. He wasn’t like them. He wasn’t telling anybody what he was like. He still believed he had an inside track on natural selection.

Now, what did he do with that theory once he knew that Wallace was onto the same thing? He believed Wallace was onto the same thing. Darwin read the paper in haste; we can all see now that they are not talking about the same thing in the same way – Wallace rejects the selection analogy for example. Absolutely basic analogy with domestic animal breeding, Wallace absolutely rejects it, always rejects it. So there’s a fundamental difference between Darwin and Wallace to begin with.

I can’t see that Darwin gives up anything. I’d have to think about it for a while before I gave you a technical answer, but it seems to be that what Wallace says and does over the next 10 to 15 years makes Darwin more attached to what he always thought. Wallace did push him hard, and Darwin said once, “It terrifies me to disagree with you,” and that was public hyperbolae, but this unprepossessing sort of guy, who left school when he was 13, he didn’t go to Cambridge. I mean he would have, Wallace would have joined The Open University and he’d have got a fine PhD, had there been an Open University in 1840.

This was an incredibly bright and underused talent, you know, and Darwin knew that. You know, they were socially chalk and cheese, and yet this guy was dorking him, and Darwin took preventative measures, hedging about his theories to make sure, obvious example is sexual selection, Darwin is so goaded by Wallace, because Wallace doesn’t believe that male competition and female choice causes sexual dimorphism in nature.

Darwin expands his work on sexual selection so two thirds of his book, on ‘The Descent of Man’, and Selection in Relation to Sex is the rest of the title, two thirds of that book is about birds and bees and pigeons and furry mammals before he ever gets to humans. Typical Darwin, he has to do the whole panoply of nature to prove that sexual selection is right and (brackets) Wallace is wrong.

Ben: And finally, what was it about Darwin that means that he stands out now? There were other people researching similar things that may not have hit exactly the same theory, but Darwin really was the man that stands out as being the father of evolution.

Jim: Evolution needs a father, as Steve Jones would say. Newton is pictured by Blake’s geometer outside the British library on Euston Road - unfairly perhaps. You think of Einstein. You think of Einstein as a brain, you know. You might think of Freud as being something really slippery. But Darwin’s a grandpa! He has a beard. He has a big family. He’s wealthy. He lives in the country. He’s contented. He cut the image of what it was like to be a gentleman of science in his day, and he still does.

Darwin is cuddly. Apart from the fact that this old man is not reliable with children because he teaches them falsehoods, some people say, this old gent is like anybody’s grandpa. You could really warm to the guy.

Now I’ve studied Darwin for many, many, many years, and I’m not particularly enamoured of him. The more I’ve got to know him, I suppose the more I’ve got to know anybody, the less I’ve been enamoured of him.

Listen to the whole programme, originally broadcast on BBC Radio Five Live, March 2009.

Find out more

Explore the reality behind the man and his theories: Darwin

Watch Jim Moore talking about his discovery of Darwin’s motivation

“We know more about the movement of celestial bodies than about the soil underfoot.” - Leonardo da Vinci.

Yes, underfoot is the soil I want to talk about, which one of my professors fondly refers to as The Book of Nature. He would say, “Open The Book of Nature and read… here and there a chapter might be incomplete or you may not understand, but you can always learn about the past, the present and the future.” Indeed, my limited reading has found a lot of interesting chapters…

What is soil?

Technically defined, soil is a "natural body comprised of solids (minerals and organic matter), liquid, and gases that occurs on the land surface. It is characterized by distinguishable horizons and or the ability to support rooted plants in a natural environment".

In a much more ecological way, it is the basic structure that supports life’s primary producers, i.e. plants. It does this as a result of its unique capability to act as a reservoir of nutrients/water and then to supply those intermittently to the plants - very much like a prudent bank.

This is not the soil’s only role; it also acts as a foundation for infrastructure and as a cornerstone in the health of ecosystems, for example, by locking pollutants and harbouring ultimate decomposers. As such, it is considered as one of the three most vital natural resources, alongside air and water.

Why care for soils?

Knowledge of the soil's physical, chemical and biological make-up is important for various disciplines. For example, nutrient levels are important for crop production, soil shear strength is crucial for engineering construction, and its structure could also be a deciding factor for football pitches! It also has more exotic uses, such as a beauty accessory (see the intricate hair-styling of the Hamer of Ethiopia, for instance).

In addition to their functional roles, soils have been part of our life and culture in many ways. A recent book, Soil and Culture by Edward R. Landa and Christian Feller, pays tribute to their impact from visual arts to religion and from archaeology to disease and warfare, and as a further example, many states in the U.S. have a specific soil that is legislatively established as a ‘state soil’, just like a state bird or flower.

What is the status of soils today?

Like most of earth’s resources, soils in all parts of the world are under threat. From the physical problem of compaction to erosion, and from salinity to pollution, are increasingly degrading our soils, with negative effects on ecosystems, economy and human health. In addition, global warming threatens to release carbon trapped in soil's organic matter, exacerbating climate change and having grave consequences for life on earth.

What's being done?

As the concern on soils has come to the forefront of public awareness, national and international bodies are moving towards legislation and action. For example, the UK government’s Department for Environment, Food and Rural Affairs (DEFRA) recently published a revised strategy on soils.

Hilary Benn, Secretary of State for Environment, Food and Rural Affairs, explains the importance of caring for soils.

Take it further

Educate yourself and others with the Soil Science Educational Resource.

Join surveys, for example, the OPAL national soil and earthworm survey.

Support those who are working to improve soils situation, such as the Soil Association.

Open University courses

Neighbourhood nature

Environment: journeys through a changing world

Other links

BBC Life

British Society for Soil Science

International Union of Soil Sciences

European Union Soil Thematic Strategy

About the author

Dr Yoseph Araya is a plant ecologist and associate lecturer at the Open University. He works on the biology and conservation of South African fynbos vegetation. Environmental education and the role of the public in research is one of his key interests.

Subscribe to Yoseph Araya's posts

 

A computer lab in Mekelle University, Ethiopia.
[Image © copyright Terri O'Sullivan, some rights reserved]

Work and life is very different to living in Northampton and working at The Open University. It's certainly taken time to adjust to the new organisation, culture and way of working. After arriving with high expectations and a keenness to get moving with the job, work felt slow in the first few months and I didn't feel like I was getting anywhere. However, everything has fallen into place recently. Now I have built up relationships and got to know the working practices, things have really started moving – and the time spent getting to know my colleagues, in particular, is really paying off. Their support and assistance has been vital; without them guiding me through, it would have been extremely difficult to achieve anything.

It also takes a while to get used to the network and power interruptions. The university is fortunate to have a 2Mb broadband connection, which, I believe, is one of the fastest connections in this part of Ethiopia – but we do have to share this between over a thousand staff. We're currently on a “power-sharing” schedule, where, during the working week, the power is off every other day. As you can imagine, this makes conducting IT training difficult. With scheduled powers cuts, you can work around this, but there are also other times when the power will go off for several hours without notice. Recently, some areas of the university have been supplied by backup generators, so this helps greatly, providing you are using the right computer labs. We're hoping this situation will improve once the rainy season is over and the hydroelectric dams are full.

The university has recently started a partnership with Alcala University in Spain to work with the Engineering and Health Sciences colleges, writing an e-learning training programme for selected tutors to attend over the coming semester. During the course, tutors will develop online activities for their students to take part in. Since student access to computers can be very limited, we're building two new computer labs - one for each college - so the students can participate in these activities. As this is pilot project, we're testing out installing thin client labs and using open source software. This is a huge contrast to the usual computer lab setup here, which consists of desktop PCs running Windows. At any given time up to three-quarters of the PCs may be out of action for a number of reasons, commonly due to virus infection, but also hardware failure. The labs then take a small army of IT technicians trying to keep as many PCs up and running as possible. We're hoping that the architecture of the thin client labs will vastly reduce the amount of support time needed, as well as being a more scalable solution, with the added bonus that it will be cheaper to increase the number of terminals.

Although most of my current work is involved in coordinating and managing these new labs and assisting with writing the training course material, I also have a few side projects to maintain. One of these involves showing staff from the Health Sciences college how to use GPSs to map the community health centres and health workers in the rural areas. The college has a number of projects in these areas measuring the impact of government schemes such as the Health Extension Programme - which gives healthcare training to local people so they can better support their communities.

Despite, or perhaps because of the problems, the sense of achievement is much greater than my work back in the UK. Knowing that you are making a real, though perhaps small, difference makes dealing with the life here all the more worthwhile. The Ethiopian people are very friendly, generous and appreciative, making it a highly rewarding and enjoyable experience.

How you can get involved

In my opinion, simply supplying more computers and hardware doesn't really help get to the core of the problem of IT development here: although more hardware will never be refused, IT training and staff development plays a greater role in development. Many staff - not only in the university but also teacher training colleges - lack the IT skills to maintain and make best use of the equipment available to them. Even computer science students arrive having hardly used a computer so a lot of time is spent developing basic skills, including how to operate word processors and spreadsheet packages. As has been reported elsewhere, viruses are a huge problem, damaging the tools that could help Ethiopia to develop. Training staff in how to install and, crucially, update their anti-virus software therefore has a significant impact.

My volunteering here is something I wish I’d done sooner. As a software developer by background, I'd often put off applying as I was unsure I had the skills needed to work in a developing country. It is a big commitment to give up a well-paid, comfortable job in the UK, but I haven't looked back. Not only have I been sharing my existing IT skills, but I have also developed new ones in terms of training, hardware and network maintenance. I'd definitely recommend other IT professionals to come and experience living and working in a developing country.

Kat Arney: They do say a rose by any other name would smell as sweet, but what does make us think that a rose smells nice but my feet smell bad? My feet don’t smell that bad. But until now scientists have known relatively little about how the smelly molecules, known as odorant molecules, are recognised by the receptors in our noses. But new research by Harumi Saito published in the journal Science Signalling this week could shed some light on this mystery.

Chris Smith: So come on then, tell us why does a rose to me smell like a rose and your feet smell, well let’s not go there.

Kat Arney: Well our sense of smell is an amazing thing and our noses have hundreds of olfactory receptors, each of which can pick up a different smelly molecule and this then sends a signal into the brain which gets interpreted as a smell. But we only know around about 50 of these smelly molecules and that somewhat limits our understanding of the whole system.

Chris Smith: So what are the researchers actually doing in this study to try and home in on what’s going on?

Kat Arney: Well they used a technique called high throughput screening which allowed them to carry out many, many experiments in a short time, and this allowed them to test 93 different odorants, these are the smelly molecules, against a panel of 464 different olfactory receptors, and they picked up 52 specific odorants that activate mouse receptors and the screen pulled out 10 new odorants that activate human receptors.

Smelling a flower.
[image © copyright Jupiterimages]

So this has, you know, made a big increase on what we know about the number of specific molecules that interact with the smell receptors. And the scientists used the knowledge from their screen to then develop a computer model that can help to predict what kind of odorant molecules might fit with different olfactory receptors.

Now it’s probably possible to look at a whole range of smelly chemicals and try and predict which olfactory receptors they might bind to. So this is basically going to speed up the process of research in this area so scientists will have better ideas of which routes to follow rather than just taking shots in the dark.

Chris Smith: It’s interesting because before Christmas I spoke with a perfumer who makes smells for a living, nice smells, and he had the chemical equivalent of synaesthesia, he could imagine a smell and see the molecule in his mind’s eye that would smell like that, so I guess he’d be very interested in a function or a model like that.

Kat Arney: Absolutely. Fascinating.

Listen to the whole programme, originally broadcast on BBC Radio Five Live, February 2009

Chris Smith: Hello, I’m Chris Smith and this is Breaking Science, which is produced in association with the Open University.

First, with news from across the scientific globe it’s time to join our science reporter, Dr Kat Arney. To kick us off, Kat, the headline in Science is quite funny but it only really works with an American accent which is ‘from oral to moral’, scientists are saying that the way we react to things that we find objectionable is all based originally on foods that we don’t like the taste of.

Kat Arney: Yes, we often use the phrase ‘it left a bad taste in my mouth’ to describe an activity or a situation that we find quite unpleasant. But now researchers writing in the journal Science have shown that there may actually be more to this metaphor than meets the eye.

Chris Smith: Pray tell why?

Kat Arney: Well the researchers, led by Hannah Chapman, wondered if there was any kind of link between the facial movements made when we eat disgusting food, you know, that sort of ‘urgh’, and when we see disgusting pictures or when we experience really unpleasant behaviour so they carried out some intriguing experiments using volunteers.

Chris Smith: I thought you were going to say for a moment you’ve been sampling my mother’s cooking. But go on, tell us, what did they do with their volunteers?

Close-up of dog taste buds.
[image © copyright Jupiterimages]

Kat Arney: Well to start with the researchers gave the volunteers different drinks, they were either neutral tasting, sweet or bitter, and then they took close up video images of their faces. And in particular they focused on the actions of a group of muscles called the levator labii, and these are the muscles that make us wrinkle up our noses and raise our upper lips when we taste something nasty. Now unsurprisingly they found that the bitter taste caused a big movement of these muscles compared to sweet or neutral tastes.

Chris Smith: Yes, but how does the disgust at things and the behaviour bit of it come into this?

Kat Arney: Well next the scientists showed people pictures of disgusting things, including poo, injuries, insects, things like that, and they compared these with pictures of sad things and then some neutral pictures for contrast, and the team found that only the disgusting pictures led again to the movement of these levator labii muscles, and the stronger the disgust that the person felt the more their muscles moved. So this is quite intriguing, and the team went on to look at situations where people experienced unpleasant or unfair situations. These were met with these same facial movements of disgust, say, seen with a nasty liquid or unpleasant pictures.

Chris Smith: So give us the bottom line, taking a financial analogy then, what does this mean in terms of how this behaviour maps onto what we actually do in real life?

Kat Arney: Well, the researchers think that this means that moral disgust and outrage actually has similar evolutionary roots to physical disgust, and they think that this physical response to something nasty has probably been co-opted during our social evolution to express our disgust at social and moral situations that we don’t like.

Chris Smith: Indeed.

Listen to the whole programme, as broadcast on BBC Radio Five Live February 2009

In an average year, we would expect about 20 quakes exceeding magntiude 7.0, so naturally the news media got rather excited as to whether the two quakes were linked. Had the Samoan quake caused the Sumatra quake? I spent quite a while on Wednesday evening talking to various print and broadcast journalists by telephone and on Skype, and was chauffeured down to London at 4am on Thursday to do a live interview on GMTV just after 6am. Some journalists also cottoned on to a magnitude 5.8 quake in Peru nine hours after the Sumatra quake, and looked for a link between all three...

The answer is that the events are most unlikely to be linked. Look at the map below: the epicentres of the Samoan and Sumatra quakes are more than 7500 km apart, and they are not even on the same plate boundary. The Samoan quake occured in what is popularly called the 'Ring of Fire' This (almost) circles the Pacific ocean, and is a system of trenches where the Pacific ocean floor is being subducted (pushed down below) continents or island arcs, running from New Zealand, northwards past Tonga (where the ocean floor is being subducted westwards, and hence the Samoan quake), thence onwards to the Philippines, Japan, Kamchatka, Alaska and down the west coast of the Americas to Chile. The magnitude 5.8 Peru quake was on the 'Ring of Fire' too, where the ocean floor is being subducted east below South America) and was entirely unremarkable because we expect three or four quakes exceeding magitude 5.0 somewhere in the world every day. Melting processes in subductioin zones, not directly related to earthquakes, feed the volcanoes that give the 'Ring of Fire' its name. An earthquake happens when strain that has built up over decades or centuries is released by the sudden, violent, slippage of a fault. The most that can be said is that a distant quake might be capable of precipitating a quake that was going to happen soon anyway. It certainly cannot cause one that was not fairly imminent.

Strictly speaking, the Sumatran quake was not on the 'Ring of Fire', despite what you may read or hear in many new reports, but was caused by the same sort of process. Here, the Indian ocean floor is being subducted northeastwards below Sumatra and Java. It was a large quake further along this plate boundary that caused the 26 December 2004 Indian ocean tsunami that claimed nearly 300,000 lives, and a smaller (magnitude 7.7) quake just offshore of Java that caused a smaller tsunami in July 2006.  There was a very intelligent report about many of these issues on the BBC's Newsnight on Thursday.

The epicentres of the Sumatran (on the left) and Samoan (on the right) quakes.  They are more than 7500 km apart, and a very complex system of tectonic plate boundaries lies between. [Map made in Google Earth]

Attention now must focus on rescue efforts, but I hope it will subsequently switch to enquiries into why buildings in Padang were not better able to withstand the shaking caused by the earthquakes. It seems that hospitals and schools collapsed. These are buildings with large rooms, and hence large extents of unsupported roofs and ceilings, but it is well known how to make such structures earthquake resistant. All too often, it turns out that seismic building codes have been flouted. I have blogged previously about shoddy school buildings in regions at risk from earthquakes, for example in the magnitude 7.9 quake in Sichuan, China on 12 May 2008 . Fortunately the local time when the quake struck Padang was after 5 pm, so presumably the schools were fairly empty - but not so the hospitals.

Take it further

Volcanoes, earthquakes and tsunamis   ⁸

Teach Yourself Volcanoes, Earthquakes and Tsunamis by David Rothery
published by Hodder Education

About the author

Dave Rothery is a volcanologist and planetary scientist at the Open University. His current research includes studying volcanic eruptions on the Earth and characterising planetary surfaces, especially Mercury.

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Like those, this tsunami was caused by an undersea earthquake, at a subduction zone where one tectonic plate is being pushed down below another. In this example, the floor of the Pacific ocean is being pushed westwards below the Tonga island arc. Plates do not slide past each other smoothly. Instead, strain builds up until the deformation is relieved in a major jerk. In this case, the 'jerk' began at a relatively shallow depth of about 18 km, and the seafloor above it was probably jolted upwards by several metres. This sudden displacement caused a series of waves on the sea surface, which became higher and steeper when they ran ashore. Local reports speak of waves reaching more than 5 metres above sealevel and rushing 100 metres inland.

Unlike the situation in the Indian ocean back in 2004, the Pacific ocean has a pretty good tsunami warning system, and evacuation of Samoa's capital, Apia, did occur although I am not sure whether this was achieved before any tsunami waves were likely to hit it, because the earthquake was so close by that the waves would arrive in less than an hour. Also the earthquake happened so early in the day, just before 7am local time, that many people may not have been aware of the situation.

Students of the Open University short course Volcanoes, earthquakes and tsunamis , which is supported by the book Teach Yourself Volcanoes, Earthquakes and Tsunamis will doubtless soon be discussing the issues and implications raised by this event. There are many current news reports, and already a rather good entry on Wikipedia.

Samoan region of the Pacific ocean
[data courtesy of US Geological Survey]

Earthquakes in the Samoa region in the 24 hours before the time stated at the top (there were none in the previous week). The largest blue square locates the epicentre of the magnitude 8.0 quake that caused the tsunami. The others are smaller aftershocks.  Samoa is the group of islands north of the earthquake swarm, Tonga lies to the south, and the outlying islands of the Fiji group are visible near the western edge of the map. The map covers a 10 by 10 degree block, approximately 1000 km across. Data courtesy of USGS.

Take it further

Volcanoes, earthquakes and tsunamis

Teach Yourself Volcanoes, Earthquakes and Tsunamis by David Rothery
published by Hodder Education

About the author

Dave Rothery is a volcanologist and planetary scientist at the Open University. His current research includes studying volcanic eruptions on the Earth and characterising planetary surfaces, especially Mercury.

Subscribe to Dave Rothery's posts

 

Chris Smith: In some countries it’s traditional to woo or serenade a woman by singing beneath her balcony. Well now it turns out that things aren’t so different in the insect world. Here’s Lauren Cator.

Lauren Cator: I’m interested in how mosquitoes choose their mate, and my hypothesis is that they may use flight tone as a way to get information about the quality of potential mates.

Chris Smith: So in other words how fast the wings are flapping?

Lauren Cator: It’s not a direct relationship but that sound that’s created by the wings flapping, yes.

Chris Smith: So what was the big unknown then that you were trying to investigate here?

Lauren Cator: There was a paper published in 2006 by Gibson and Russell, and they found that in Toxorhynchites, a large non-blood feeding mosquitoes, that a similar behaviour was occurring, and, as a medical entomologist, I was interested in seeing if medically important mosquitoes, mosquitoes that feed on human blood and transmit pathogens that infect people, were doing similar things.

Chris Smith: Well this seems like a very good time to bring in Ben Arthur who’s another researcher on this paper. Ben, how did you actually investigate what was going on with these mosquitoes to see how they were tuning into each other’s wing beat frequencies?

Ben Arthur: Well it was a two-part study. We had behavioural methods and some physiological data as well. In the behavioural data, what we did was we tethered individual mosquitoes to a fine insect pin with some glue and positioned them next to a special microphone which could sense the wing flight tone very finely and just listened to what they were doing.

[Sound of mosquito]

So what you’re listening to right now is a male mosquito singing along at around 600Hz, and he’s next to a microphone. And we’re going to bring in a female here.

[Sound of mosquito]

And she’s singing at 400Hz. And the higher harmonics at 1200Hz, the shared harmonic, if you listen real close, you can hear the beats produced because those two frequencies are so close together. And that’s what’s happening when they’re courting.

Chris Smith: So which sex is changing its wing beats in response to the other?

Ben Arthur: They both do. So if the male’s relatively stationary and the female comes in she’ll modulate her tone up or down to match his, or if the female is stationary and then the male can move his and they’ll just synchronise to actively both match each other.

Chris Smith: You’re saying it’s not actually the frequency the wings are beating at, but the harmonics, the multiples of the frequency the wings are beating at, which seems to be important?

Ben Arthur: That’s right. So the natural occurring frequency of the female wing beat is at 400Hz and that of the male’s at 600 and those are different enough that they don’t try to match the fundamental but rather the shared harmonics are the integer multiple at 1200Hz.

Chris Smith: How does the mosquito that’s the recipient of these frequencies, how does it actually detect them, and how do you know that it’s actually responding to the frequencies, and then how does it then know, right now I need to mate?

Ben Arthur: Right, well it has these very plumose antennae, and these antennae sense the movements of the particles in the air, and there’s a sensory organ at the base of the antennae called the Johnston’s organ which transduces that movement of the antennae into an electrical voltage that the nervous system can then use to detect where the sound is, and what it is and whether it’s a mate or not.

And the second part of our study then recorded from the Johnston’s organ and saw these electrical voltages and we found that we could measure electrical voltages all the way up to 2kHz which includes that shared harmonic at 1200Hz.

Chris Smith: Wasn’t there some claim previously by other people though that mosquitoes a) were deaf anyway and b) that they couldn’t hear sounds that high in frequency, so you’ve really scuppered both those myths haven’t you?

Ben Arthur: That’s right, exactly, and we’ve shown it with both behavioural data and physiological data in the same paper.

Chris Smith: Lauren, what do you think that the major impacts - apart from obviously this being academically very interesting - what do you think the main other impacts are from a medical point of view?

Easy to repel - but how would you attract a mosquito?
[image © copyright Jupiterimages]

Lauren Cator: Well just generally we know very little about mosquito mating behaviour, and we have no idea who’s choosing who or how they’re choosing them, and one of the control strategies that’s been proposed is to create transgenic mosquitoes - so mosquitoes that through genetic manipulation are either unable to transmit pathogens or are sterilised. The idea would be that if you release these into the wild that males carrying your desired genotype would be able to compete with wild males for female mates, and drive the genotype through the population. Unfortunately we have no idea what constitutes a sexy male mosquito.

Chris Smith: Hopefully they’ll find out soon. That was Lauren Cator and before her Ben Arthur. They’re both based at Cornell University, and they’ve published that work in this week’s edition of the journal Science. And if you’d like to read a bit more about how animals use sounds to track down a mate or find their way around there are links to a number of articles about those subjects on the Breaking Science website.

You can hear the mosquitos - and the whole programme - on the Breaking Science website. This interview was originally broadcast in January 2009 on BBC Radio Five Live

Find out more

Margi Clarke explores the science of love

How can you research animals we can’t see or hear?

How do we listen in to the animal kingdom?

How do mosquito repellents work?