How Biology Is, Or Is Not, Different: Thoughts from Ernst Mayr

Ernst Mayr was one of the leading figures in modern biology. He was the last surviving architect of The New Synthesis of evolution. And he kept writing books until he died at age 100 in 2005. Because of his age, his writing is fairly clear: he knew he did not have time to go off onto tangents. He had to get to the point, since he knew any sentence might be his last.

One of his main points (expressed in two books, This is Biology and What Makes Biology Unique?, which are very similar but not quite the same) is that biology cannot be judged by the same standards of scientific rigor as the physical sciences. Yes, we all know that biological systems (such as organisms) follow natural laws. But each biological phenomenon is the result of such a prodigious number of interacting natural laws that you can never exactly predict what is going to happen. The best example is evolution. Immanuel Kant said that there would never be a Newton for a blade of grass. Several writers have noted that Darwin became that very person.

But Darwin was a “Newton for a blade of grass” because he changed our view of biology the way Newton changed the view of physics. What Darwin did not do was to establish a system by which the exact course of evolution could be predicted. One reason for this is that each organism is unique, while each electron is the same as every other electron. It is true that the molecules in a glass of water are different from one another; each has its own kinetic energy, and some of them have hydrogen and/or oxygen atoms with extra neutrons. Although one could say that a glass of water has a “population” of molecules, they do not differ from one another in the extreme way that organisms in a population do.

I will let you read Mayr’s books, if you wish. But I want to remind all of us that there are some laws of nature that biological systems always follow. They include:

• The rate of diffusion (of molecules, heat, electrons, etc.) is proportional to the concentration or energy status divided by the resistance. One of the components of resistance is distance; it takes a molecule four times as long to diffuse twice as far. This is why diffusion is rapid over short distances, such as a synapse, and slow over long distances, such as a room. This is true everywhere in biology. This is why leaves and animal tissues both have numerous, tiny vessels. I am aware of no exceptions.
• A related concept is that an increased surface-to-volume ratio increases chemical activity. This is why kindling burns faster than a log, and why bacteria can metabolize so quickly. Any exceptions?
• A third example is from fluid dynamics. The rate of fluid flow is proportional to the fourth power of the diameter of the vessel. This law is always true for laminar flow, such as in blood vessels and xylem. Any exceptions? For larger things, such as water pipes, gas pipes, and rivers, it is almost true, but turbulent flow (when the fluid starts roiling around) slows the fluid down.

Most scientists agree with Mayr. This is the main reason that I am seldom interested in mathematical models of biological phenomena. A few decades ago, various botanists figured out equations for how much transpiration was needed to cool a leaf off, and how big or small a leaf should be to keep from overheating, and other such things. The equations gave a verisimilitude of precision. Actual leaves may or may not follow these equations precisely. They are good generalizations, but no more than that.

I recommend the writings of Ernst Mayr, even if you are not a professional scientist. Even at age 100 he had an all-encompassing mind.

Does Science Kill the Spirit?

Just posted: a Darwin video about global warming, soil, with a mole joke at the end.

Some people in the humanities perceive science as a threat. They think that it turns all human creativity into the mere operation of neurons, the product of a complex brain computer. A scientific explanation of creativity, in terms of action potentials and neurotransmitters, may, they fear, kill the spirit.

When I was an undergrad, I took music theory courses. I learned about the overtone series, and how the notes of major chords blended together within that overtone series, whereas the notes of a minor chord created discord because they differed from that series. An overtone series occurs when the vibrations at a certain frequency, say 256 Hertz for middle C, also create resonant harmonies at higher frequencies, first at the octave (512 Hertz, or twice that of middle C), then the fifth above that (G), then another octave (high C, at 1024 Hertz), then the third above that, which is E. C major contains C, E, and G, while C minor contains C, E-flat, and G; the E-flat grates against the natural overtone of E. Major chords make us feel at peace, while minor chords make us feel on edge. This is usually interpreted as happy and sad. This is not quite true; Andean music, for example, consists largely of minor-mode melodies that are happy. Even if you do not know anything about chords, your emotions can be affected by hearing these chords. One could say that the human mind, with all its happiness and sadness, is the plaything of the laws of physics, particularly the overtone series of vibrations.

Furthermore, the overtone series can explain the differences in what musicians call timbre, which can be figuratively described as the color of the sound. A flute and a trumpet playing the same note, for example 512 Hertz, sound very different, because the trumpet has more of the high, piquant overtones than the flute. So also, the overtone series explains why you need to avoid certain compositional mistakes, such as doubling your leading-tones or having parallel fifths.

I learned this, and knew it, yet at the same time I was able to participate in the near-magic of musical experience. I knew that all of music could be explained by the mathematics of vibrations and by the human brain’s response to them. But I still imagined music as magic. At the time, I was a creationist, and believed that music was literally divine. It never occurred to me to worry that my knowledge of the physics of sound might destroy the magic of musical experience. I knew just enough about music to be able to write some mediocre stuff of my own, and just enough to be frustrated when I heard works of true genius, such as those of Mozart. You think Mozart’s music is nice; I understand why it is not only nice but profound. (You’ve never heard my “Emmaus Road” symphony of 1977? Thank God it was never performed or recorded.)

And so it is with all of science. A biological explanation of the working of the human brain in no way destroys the wonder of human creativity. Explaining religion in terms of stimulation of the right temporal lobe does not negate the transcendent experience of religion. Franz Schubert put the poetry of Wilhelm Muller to music in Die Winterreise, proclaiming that all our joys and all our sorrows, “alles eines Irrlichts Spiel,” they are all the playthings of illusion. Everyone who has sung Die Winterreise, including the late great Dietrich Fischer-Dieskau, could experience the transcendent beauty of this line of music, even while proclaiming that this beauty is a mere illusion of the mind. You see, when we are participating in music, or in the world of nature as explained by science, we are inside of it, and the mathematical and physical explanations do not destroy the evolved capacity to experience them as transcendently inspiring experiences. We can analyze our animal evolution, but we are still animals, exulting inside of those experiences.