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I think we’re all biologists on this bus: two quickies

November 8, 2005 at 10:21 am · Filed under Uncategorized

[You have insufficient information to know this, but my biologically-themed posts tend to arise from days when I ride the bus to work. It's what you get from my two hours of sitting still, looking quietly out the window, and meditating, instead of poring over linear programming problems, old texts, politics or the sorry future of Operations Research. 'Twas a bus day today.]

First: It is noted that, during autumn, many fallen leaves are observed roughly evenly distributed over the neighbors’ and University’s lawns, but that there are almost no leaves to be found immediately under any trees. Pick your favorite hypothesis, or add another in the comments::

  • The leaves of many trees curl when they dry before falling, making an aerodynamic shape that allows them to glide far away from the tree they grew on.
  • Lawn, being dark and relatively short, tends to accumulate more dew than other surfaces on the cool nights of autumn, which dew adheres the blowing leaves more fully than other flat surfaces.
  • The action of dogs and squirrels around the base of trees tends to shift and fluff up piles of leaves that might be there, allowing them to dry more fully and blow away more quickly than those in other parts of the lawn.
  • Winds tend to form vortices around the trunks of trees, which in turn lift the leaves up away from the ground more than leaves in large flat expanses, where the wind is more laminar.

(I actually hold a different one, related to one above but involving bare soils and allelopathic chemicals.)

Second: How long until consumer protection groups start to sue makers of antibacterial soaps, for failing to act on their understanding of the process of natural selection, which will lead to resistant strains of bacteria and an increase in the prevalence of life-threatening diseases? How will the ID people respond to such a suit? Will the soap-makers take the stance that it is not their place to take a stance on a controversial issue? Will they say they “never considered” the ramifications of ubiquitous but gentle selection pressure?

Branko Collin said,

November 8, 2005 @ 9:11 pm

I think the only logical hypothesis is that leaves fall from heaven, but trees protect the ground from the leaves with their branches. After all, if you emptied a bucket of m&ms over my head while I held an open umbrella up, the m&ms would least likely end up directly in the space shaded by my umbrella. I think. I’ve never actually tried this. Do you think an experiment like that would be grant material?

Bill said,

November 8, 2005 @ 11:27 pm

You know, there was a day one autumn I recall vividly. It was a warm clear day, just after the first few cold days in fall that year, and I was walking along a quiet street on a campus, near a sports field. I noticed something odd, and looked up, and there was a silent, towering dust devil, maybe 5 meters across and 500 meters tall (what I could see of it). I saw it not because of the dust, but because of the leaves it picked up as it wandered along the ground.

It was slow, and I walked over to it and walked along inside the vortex for a while, until it hopped a fence I couldn’t cross. Very memorable, spending ten minutes or so in the midst of a gentle whirlwind.

Anyway: add dust devils and/or small whirlwinds to the umbrella hypothesis, and we have the “leaves from heaven”.

Maynard Handley said,

November 12, 2005 @ 9:40 pm

It was my understanding (correct me if I am wrong) that anti-bacterial soap is not really a big issue because the mechanisms used by such to kill bacteria can be pretty damn blunt (and thus pretty damn difficult to evolve around), simply because soap is for external use, so a blunt mechanism that also (in some mild way) hurts human cells is OK.

Antibiotics, on the other hand, are much trickier because now you have to find something to attack that is specific to bacterial cells and not part of human cells.

Given the horrifying statistics I saw on some blog a month or two ago (37% of US doctors don’t believe in evolution, and let’s face it, probably a large number of those that do probably can’t put two and two together), the real issue here would appear to be the medical profession. A third possible villain (I don’t know enough about this) is antibiotics routinely pumped into animal food.
I suspect both of these are far more important than anti-bacterial soap.

Bill said,

November 14, 2005 @ 11:42 am

Anti-bacterial soap contains compounds that do, indeed kill bacteria more effectively. Sure, it may be true that some ways of avoiding selection of and exposure to dangerous bacteria may be better than others. But, who told you that killing bacteria not on your hands was a good thing?

If people use small enough amounts of anti-bacterial products, so that they are not washing most of it off into the sewers, then they may be imposing a powerful but incomplete selection pressure for bacterial resistance. Remember that strong acid, high temperatures, and radiation and the harsh vacuum of space are all also very good at killing bacteria.

Oh, wait — there are bacterial species that survive quite handily in all those environments. Are they pathogens? Naaah. But they can do it. As my old colleague Ian Malcolm at SFI once said, “The history of evolution is that life escapes all barriers….”

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