Tsetse flies: Why evolution and climate change matter

I thought I would give you a sense of my work in science to give a better context for what I do for a living. Plus since it involves both evolution and climate change it gives me a chance to promote two of my favorite topics and the focus of this blog!

So what do I do? I study tsetse flies. Here is a picture:

http://www.dkimages.com/discover/previews/887/20001636.JPG

http://www.dkimages.com/discover/previews/887/20001636.JPG

These flies are rather strange. Unlike most flies which lay gazillions of eggs, these flies lay a single egg within their abdomen that they keep internally until the young larvae is ready to pupate at which time they carefully lay the little tyke in the ground. They can do this at most about nine times, a rather modest reproducer compared to their cousins. Flies that carry their young internally? I bet you didn’t know that! These flies are blood feeders, like vampires, except they can see themselves in the mirror. But they do carry a bit of terror about them. They carry some cracking bad diseases. And the trouble is they have evolved away from most of the medicines that treat the disease. Evolution in action. This is a picture of Trypanosoma brucei the organism carried by the fly that causes sleeping sickness*:

These flies do a lot of damage in equatorial Africa. It’s called the poverty fly. Why? Not only does it cause problems in human health, but it also affects draft animals. Last year, when I travelled through Ethiopia, right at the beginning of the rainy season, people were preparing the ground for crops:

dscn2752

Because animal power is the principal means of growing crops, there are regions where people can’t grow crops because of this fly. If you look at maps you can see patches of Ethiopia where the fly does not hang out. These are generally areas where the fly has been blocked by natural barriers in hilly and mountainous regions. The distribution of the fly is based on elevation because it is very sensitive to drying and cold. If you set a line of traps up an elevational gradient, you can mark a line where they just stop. Unfortunately because of the warming climate the places where the fly can’t reach is changing and the fly expanding its range. This has a direct impact on where people can grow food. Because animal traction is how plows are pulled, this is catastrophic. When people think about climate change they, often think only about the impact that affects Western industrial society. In Africa the changing climate is effecting real changes to people’s lives. They live much closer to disaster. When global food prices doubled last year people in my Utah neighborhood where complaining, but as far as I remember none of my neighbors starved to death. When I was in Ethiopia a news report from a remote village reported that several children had starved to death because people could not afford food (you’ll remember last year corn and rice prices doubled in the course of about a month). Could not afford food. Think about that. This is why Climate Change is an ethical matter, not just a matter of fact (although as far as climatologists are concerned the case of human caused climate change has been made). If there is a chance we can do something, we ethically are bound, to do so. People are dying over it. It’s not just a matter of higher gas prices.

Back to tsetse flies.

How do you get rid of them?

One way is to trap them. These targets (the blue thing in the distance) have a pesticide to kill the fly and a cattle urine bottle to bring them in. No, they don’t look much like cattle, but beauty is in the eye of the beholder and tsetse flies love these blue squres:
dscn2715

Another way is to put pesticide on the cattle directly. The day we were there over 2000 head of cattle were treated:
dscn2817
dscn2820

And still another way is to raise thousands of flies in a fly factory (this one is located outside of Addis Ababa) and sterilize the males and release them into an area. Females only mate one or two times and if they have mated with these sterile males that have had their sperm nuked by radiation then they don’t have offspring. There is what the inside of a fly factory looks like:
fly-factory

(And next time you hear about “Pork barrel” spending on the sex lives of flies, look a little closer. Such research was necessary to produce this sterile fly technology and has not only helped tsetse fly, but has saved the California fruit industry. Really.)

So this is what I do. I’m building mathematical and computer models to help suss out how to best approach combining these practices into a coherent strategy for fighting this fly. “Using real math to make the world a better place.”

This last month I travelled to Senegal to assist in their efforts to control tsetse fly. Senegal has some of the same challenges with climate change, as well an additional change. Animal traction is still used to prepare the soil (I’ve never once seen a tractor in the regions I work in Africa), but the desert is creeping into larger and larger areas of Africa. The ‘sub’ is getting smaller in Sub-Saharan Africa as the ‘Saharan’ part gets bigger. It’s getting drier every year.
sale

But the fight goes on. Here I directly engage with the beast. That’s a real tsetse fly. I didn’t let it bite me:
me-and-tsetse

Here the research team sets up monitoring traps:
research-team

We catch some:
we-caught-some

So that’s what your intrepid blogger does in his spare time. And that is why I care about evolution and climate change. I see it affecting people. I see it happen in my work. I use evolution constantly (Note here, because I can see it coming: Creationists have glommed onto a funny concept. There is a heuristic used by evolutionary thinkers made between micro and macro evolution. This is used only to make timescales of interest distinctions, not biological ones. Creationists will sometime claim to allow micro, but not macro evolution, which to a biologist’s ear sounds a bit like, ‘I believe in inches, but not miles.’ Macro is just micro over a long time. Once you start thinking of species as strings of DNA rather than fixed species the distinction gets silly).

Now lastly, one aspect of international research is that you get to see all kinds of interesting species, like this slipper lobster,
slipper-lopster

and then eat them:
cooked

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23 comments to Tsetse flies: Why evolution and climate change matter

  • You point out that “creationists will sometimes claim to allow micro, but not macro evolution, which to a biologist’s ear sounds a bit like, ‘I believe in inches, but not miles.’”

    A cogent analogy. I’ll have to add that to my own bag of explanatory tricks. Thanks.

  • From a Stay-At-Home Mom in Zion, I say: keep up the good work and thanks for your insights on global warming as an ethical problem.

  • Have temperatures in Africa been rising over the past ten years while those in North America have held steady or declined?

  • The kinds of evolution actually observed by modern scientists have involved switching on an off existing mechanisms in the DNA design files of living creatures. This is generally all that is needed to confer immunity from certaih antibiotics, for example. What has not been documented is the creation of original complex mechanisms. If that had in fact been observed, it would be widely publicized as convincing proof of the creativity of random mutation and natural selection or other non-purposeful causes of evolution. This is not to say it is not possible such an example could arise in the future, just that it hasn’t shown up yet. For this reason, the assertion of the Darwinian synthesis that materialist causes can completely explain all mechanisms in living things is still an inference rather than a simple observed fact.

    Just as Newtonian physics has come to be seen as a theory that works in many cases but not all, the neo-Darwinian synthesis may be a theory that explains many aspects of life, but not all of them. Just as Newtonian physics is still used in many practical applications, evolution can continue to be used and useful in innumerable applications, even if it is not quite as comprehensive and exclusive an explanation for the nature of living things as many people want it to be. Those like Richard Dawkins who insist it must be the sole explanation are actually reasoning from their belief that only observed material causes can have ever affected the development of life over the earth’s billions of years of existence. He continues to maintain this, even though it is clear that biologists are already starting to make purposive changes in living things, and are driving toward the goal of creating new and original mechanisms in living things, the most promising area of “nanotechnology”. It is not unreasonable to think that, a century from now, if we see an unusual and complex mechanism in a living thing, it will be a legitimate question whether it came about naturally or through intentional manipulation by a (human) intelligence. The only reason to reject the second possible cause right now is the belief that there did not exist until now an intelligent being on earth that was capable of doing such intentional genetic manipulation. But if random Darwinian mechanisms of evolution lack the creative power to do the job, the existence of such complexity in life is a candidate to serve as evidence of precisely the existence of such a prior intelligence.

  • Tim

    Raymond,
    Please elaborate on this sentence: “What has not been documented is the creation of original complex mechanisms.”
    What does “original complex mechanism” mean? Could you give an example? And what level of documentation would you require?

  • Tim

    By the way, Steve, I particularly appreciated this example of science in action, and why all of this stuff actually matters. Thanks.

  • Jeremy

    Wonderful. Thank you.

  • SteveP

    #4, “The kinds of evolution actually observed by modern scientists have involved switching on an off existing mechanisms in the DNA design files of living creatures. ” This is not true of insecticide resistance in general.

    It is also incorrect to assert that because we can manipulate genes means that an intelligent agent manipulated it in the past. The story is written in the genes we can see it. It’s not a story of manipulation. Can you cite one peer paper to support your view (that’s not out of the discovery institute).

    The new science of evo-devo which combines an understanding of natural selection and embryonic development as done nothing but strengthen the case of evolution by natural selection. I know of no currently publishing biologist that thinks differently. Yes, we are adding complexity to the story, but evolution by natural selection is still in operation fully. In fact it’s what makes Evodevo make sense.

    “What has not been documented is the creation of original complex mechanisms. If that had in fact been observed, it would be widely publicized as convincing proof of the creativity of random mutation and natural selection or other non-purposeful causes of evolution.”

    Lenski does it here:

    http://rationalwiki.com/wiki/Lenski_results_challenge_creationism

    there are many examples. Somehow the creationists still aren’t convinced.

    Read the other entries in almost every entry in this blog that show why ID is a bad science and bad Faith and unnecessary to LDS thought, faith, and belief.

  • Kari

    Steve,

    Excellent post.

    I’m always astounded by the lack of understanding in evolution that folks like Raymond show when they expect an new organ like a pancreas, liver, or eye to develop or been seen to develop in the infinitesimally short time that science and scientists have been observing and studying natural selection and evolution. Or that will be observed in our life span.

    We’ve been at this for a hundred years. The age of the universe is what, 13 Billion? With life thought to have been in existence on earth for 4 billion.

    By my simple calculation we’ve been watching nature evolve for all of 0.0000025% of the span of time life has existed on earth. Does Raymond really expect to see a change in a hundred years that took billions in the past?

  • Eric Chambers

    As an LDS biologist currently involved in a project concerning the control of lymphatic filariasis I found this post to be very interesting.

    I’m curious. How long has the integrated control program you outlined been in effect? Has there been any measureable impact on disease transmission? Or is it still too early in the study to know?

  • Eric, Yes indeed. In the Ethiopian project (it’s just getting started in Senegal) we do see a reduction in disease!

  • Dave

    Steve, are you also considering in your models approaches that try to prevent the trypanosomes from completing their development in the flies, rather than just killing flies? Using the symbiotic bacteria in the tsetse flies to express anti-trypanosomal proteins for instance, and then spreading these paratransgenic flies to replace the native flies, in conjunction with the sterile male approach seems like a good idea.

  • Jeremy Foote

    I’m sorry to post off-topic, but I just wanted to tell you that I have deeply enjoyed your blog (other than your truly horrific spelling – :) ), but there are a few issues that I have been pondering about, and I was wondering about your opinion on the following:

    1. Given evolution, who is Adam? The LDS theology seems to argue for an actual individual that was the “first man” in some sense.

    2. How are we created in the image of God? Do you think that evolution is directional (i.e., at some level, God directed mutations to result in beings that look like him)?

    Many thanks!

  • SteveP

    Dave, They’ve tried several approaches but when things do work, the trypanosomes have evolved mechanisms to overcome them. There are medicines, but there haven’t been any new ones, and resistance has developed quickly and is spreading. Only about five years ago people thought that medicines that target the trypanosomes would be all we need, it’s swung back to the best approach being vector (tsetse fly) control.

    Jeremy, yea my spelling is disastrous! See this.

    On the Adam question look at this post, and on direction of evolution question look at the four-part serious that I just did a few posts ago. It will answer many of your question (keeping in mind there are many things we just don’t know).

  • kevinf

    Thanks for broadening my worldview a bit. You do good work. Keep it up, and we’ll try to keep the pork coming from Washington DC so you can continue.

  • Kari

    Happy blog birthday Steve. One year old today. Congratulations.

  • SteveP

    Oh, My Heck Karl! Thank you! I did not even notice! Thank you, it’s been a fun year for me. My baby. One year old. I can’t believe it!

  • [...] “And that is why I care about evolution and climate change. . . I see it happen in my work.” [...]

  • I was talking with a simulationist this week-end. He said that given that there is global warming on Mars and additional growing seasons in Greenland, it was pretty much well past theory that things were warming.

    His only thought was that if we could get the oceans circulating again, Antarctica would go back to being fertile like it was.

    All that aside, I really found this interesting.

  • SteveP

    Stephen M (Ethesis), And if we could get to work terraforming Mars we would be really moving forward!

  • JDD

    Nice blog. I suspect it’s just a type-o, but the name of the organism that causes African Sleeping Sickness is “Trypanosoma brucei.” The only reason I know is because it’s been one of the focuses of my own research. Keep up the good work!

  • John Mansfield

    Sitting down with Physics Today last night, I came across an exchange that reminded me of this tsetse fly post. If interested:

    http://ptonline.aip.org/journals/doc/PHTOAD-ft/vol_62/iss_4/8_1.shtml

  • SteveP

    Thanks JDD, I corrected it in the Post!

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