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TWiP 56 letters

Suzanne writes:

Your discussion about technology and fixing things here before we go out into space made me wonder if space exploration might turn out to be like investigative science. In the process of exploring space we might run across the means of fixing our problems here.

Robin writes:

Ecology and parasites

Just as "weeds" are plants that seemingly have no use for us, but interfere with our attempts to cultivate plants in controlled ecosystems set up by us, parasites are organisms that interfere with the controlled ecosystems that constitute organisms, but seemingly have no use in the limited perspective of human timescales.

The parasites may have substantial functions in shaping natural ecosystems, such as in controlling population overgrowth, helping in modulating immune systems (as in preventing autoimmune bowel disease in humans with intestinal parasites, and in building herd immunity - which was lacking in New World humans to Old World viruses, causing New World human populations to be wiped out on contact with Old World humans) and quite possibly other influences as yet unrecognised.

Extermination of wolves - perceived in the same light as parasites - caused an overgrowth of herbivores, altering plant populations and affecting the ecology of streams and rivers.

Parasites can have effects on human social structures, as when the Black Death so reduced serf populations that they brought an end to the structures of mediaeval serfdom in Europe.

We have been around for 200,000 years, and have had an understanding of the organisms we call parasites for but a couple of centuries. Our attempts to reshape natural ecosystems to what we see as our advantage in our timeframes may have unintended consequences on evolutionary and geological timescales.

Parasites and hosts are in a dynamic dance within ecosystems, a dance that contributes to shaping the ecosystems over various timescales of which we see but a few frames, and even a small part within each of those frames.

This is so well exemplified in virology, where we have only recently come to recognise that our very existence now depends on ancient viruses that melded into our genomes.

Parasite ecology:

He also sent:

The Red Queen was Right

Blaine writes:

Hi there Twippies,

I saw this interesting link on the USDA website discussing the work of Eric Hoberg on the origins of tapeworms:

I would love to hear you guys interview Eric or have a podcast discussing the origins/evolution of some of these parasites. I find it remarkable to think about these complex lifecycles and how these parasites require two or more hosts to survive. It just doesn't seem like a great strategy for survival (other than the fact that it does seem to work). This leads to a lot of questions about how or where these things ever came from regarding tapeworms that use domesticated animals as part of their lifecycles.

One more question that you may or may not have hinted on in your podcasts. Do parasites have parasites (or commensals)? There must be bacteria and viruses that infect or live on parasites. Is anyone studying them. Can you comment on this too?


Fort McMurray, AB

John writes:

In TWiP 51 you speculated about the effect of wing muscle modifications on mating success in mosquitoes.

The subject of wingbeats and mating has been studied in the related family Chironomidae. Both families share an enlarged Johnston's organ
(hearing organ) in male antennae. Chironomidae are abundant and don't try to eat researchers, so they make better test subjects.

Males of most species form aerial mating swarms and listen for the wing beat frequency of females of the same species. I doubt females
listen for individual males, because they lack modified antennae. They may hear the swarm, and males could listen to each other to form into
a compact swarm.

A male of one of the larger lake-dwelling species might (metaphorically) say to a female:

"Meet me 5 meters over a contrasting dark object on the sandy beach at dusk when light has dropped below 50 lux. Beat your wings at 370 Hz
adjusted by 10 Hz per degree C of ambient air temperature above or below 20 C. I'll be waiting with a million of my friends."

The combination of swarm marker, altitude, and wing beat frequency is different for different species.


Ogawa and Sato. 1993. Relationship between male acoustic response and female wingbeat frequency in a chironomid midge, Chironomus
yoshimatsui (Diptera : Chironomidae). Medical entomology and zoology. 44(4):355-360.

To tie this back to parasitism, here is a picture I took of some ectoparasitic water mites on a midge (Chironomidae):

Joe writes:

Vince and Dick

As always I love your podcasts. You all made me laugh in TWIP episode 55 With Dick’s comment about the foreign nature of Chemical Engineers’ brains and Vince’s post modern nonsense about the evils of the internal combustion engine and denigrating it because it is was just so cheap.

Well let me take you on brief tour of how this Chem E’ brain sees the world.

The development of mechanical power to replace human and animal power is one of the single most important advances in human history. You may have heard of it, its called the Industrial Revolution. The rise of mechanical power is arguably the single biggest reason for the economic and moral decline of slavery as a viable social model on most of the planet. Slavery was rampant in the birthplace of democracy, ancient Greece, and not seen to be incompatible as it freed up the rich folks to have time to think deep thoughts. Mechanical power ranks right up there with the invention of writing, cities, mathematics and the scientific method as the most impactful events in our history that have enabled us to reach the incredible quality of life we have today. It has certainly had a much greater impact on the world than modern medicine or electronics both of which I value highly!.

The internal combustion engine in its various forms (2 stroke, 4 stroke, gas and diesel) is one of the single most successful inventions in history. It has beat out water power, steam power, coal fired boiler power or any other options in almost all applications with a few notable exceptions like centralized electricity generation. It is dependable, cheap, easy to repair, durable and scalable. This is the highest praise an engineer can give.

It has filled every available power generation niche in almost every conceivable human habitat and pushed its competitors to extinction. Here is a short list: weed whackers and leaf blowers, motorcycles, cars, buses, trucks, tractors, trains (diesel electric locomotives), ships, airplanes, portable generators, portable pumps and air compressors, One of the amazing things about the IC engine is that it has dominated applications where capital outlay is small with accompanying higher high operating costs (small engines) right on up to those larger applications where capital outlay is very high with relatively lower operating costs (locomotives, semi trucks and medium sized ships) Only at the very largest scales where turbine engines have an advantage do they lose out. Think E coli the size of an elephant for comparable biological example!

Imagine life in any large city without the IC engine. The quality of life drops dramatically. Public transit, food delivery, waste disposal, etc. all depend in the IC engine. I leave it to Dick to discuss the health and comfort impacts of all of us going back to horses. Don’t mind the flies and careful where you step!

Yes I know fuel cells and hybrids are so much cooler. Some day they may be one tenth as durable and successful as the IC engine. Some personal history will give some perspective, I started in a industrial R&D department in 1981 fresh out of college and I thought it was really great that about half of the R&D budget for this chemical company was going to developing membrane technology (AKA microporous separators) for use in electro chemical cells, which are essentially fuel cells running in reverse. We all saw the promise of the technology even then. They finally gave up years and many $$ later with little progress. The state of field has changed little since then and you can make the argument that this is a problem on the order of difficulty of our efforts to cure cancer. The devil is most certainly in the details. We engineers will keep working on these new technologies because that is how our brains are wired and there are some incredible advantages if we can ever make them work. But don’t disparage the IC engine until you can show me one of these new solutions going 200,000 miles over 10 years without several major rebuilds like so many old trucks and cars do ever day. Realize that the telling measure is that people only shocked when an IC engine breaks down much sooner.

If you stop and think about it, we all literally depend on IC engines on a daily basis in many ways. So the only real question is; “Have you hugged your engine today?”

All my best. You folks make my daily ride behind my IC engine a treat and are greatly appreciated!


PS. Yes machines are alive, just like viruses!

EH&S Manager

Amanda writes:

Hey guys!

Avid fan here, love all your podcasts, weather updates, and especially Dickson's digressions.

Just a teeny correction from TWiP #55. A listener (Jessie) picked the board game Pandemic. Unfortunately, you confused the board game with the flash internet game Pandemic 2. Minor, I know, but I don't want you, or any listeners, to miss out on the board game by thinking it's the same as the flash game. The two games, while equally awesome, are completely different.

In Pandemic 2 (The internet flash game and iPhone app) you build your pathogen and try to decimate the world through disease.

In the board game Pandemic, you work with 3 of your friends to eliminate 4 different diseases - developing cures and thwarting outbreaks. The game has a few levels of difficulty, and the expansion brings new elements like a mutated strain, a bioterrorist role, and even petri dishes to keep your game pieces in.

I highly recommend it! I was wary about the cooperative element, but it's a blast.

If I may, I'll submit the expansion as a listener pic: Pandemic: On The Brink
Also, for those that love Pandemic 2, there is an iPhone/iPad/iTouch app out there called Plague Inc that is very similar, but with a slightly nicer interface: Plague Inc

15 degrees Celsius and rainy here in Halifax, NS, Canada.


Post-Doctoral Fellow
Canadian Center for Vaccinology
IWK Health Centre
Halifax, NS

Judith writes:

My husband discovered TWIM for me. It was love at first podcast. I am retired after a wonderful and exciting 40+ year career in Public Health in San Luis Obispo, CA.

I have tried to keep up with Internet articles but your podcasts bring me back into the latest happenings in such an entertaining manner. Having gone through all the TWIM's I am now into the TWIP's. I love all of the regulars & am amazed at the collective depth of knowledge.
I have a strong background in evolution and ecology and love when you put the pathogens in their "places" in the big picture.
Mycology was my greatest love ... would enjoy a "TWIF"! Maybe you could clone yourself Vincent!

Question: Why TWI Parasitism rather than This Week in Parasitology for uniformity ?

I just found this article ... It is heartening that microbes are working hard to fix our messes.

Many thanks for all the hours of enlightenment! ... Judy


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