Progress vs. Variation -- Part I

An argument against "progress" and instead for INCREASING VARIATION in evolution, from Full House, by Stephen Jay Gould

1. Life's necessary beginning at the left wall.
The earth is about 4.5 billion years old. Life, as recorded in the fossil record, originated at least 3.5 billion years ago, and probably not much earlier because the earth passed through a molten period that ended about 3.8 billion years ago (the age of the oldest rocks). Life presumably began in primeval oceans as a result of sequential chemical reactions based on original constituents of atmospheres and oceans, and regulated by principals of physics for self-organizing systems. (The "primeval soup" has long been a catchword for oceans teeming with appropriate organic compounds prior to the origin of life.) In any case, we may specify as a "left wall" the minimal complexity of life under these conditions of spontaneous origin. (As a paleontologist, I like to think of this wall as the lower limit of "conceivable, preservable complexity" in the fossil record.) For reasons of physics and chemistry, life had to begin right next to the left wall of minimal complexity -- as a microscopic blob. You cannot begin by precipitating a lion out of the primeval soup.

Progress vs. Variation Part II

An argument against "progress" and instead for INCREASING VARIATION in evolution, from Full House, by Stephen Jay Gould

2. Stability through time of the initial bacterial mode.

If we are particularly parochial in our concern for multi-cellular creatures, we place the division in life between plants and animals (as the Book of Genesis in both creation myths of chapters 1 and 2). If we are more ecumenical, we generally place the division between unicellular and multicellular forms. But most professional biologists would argue that the break of maximal profundity occurs within the unicells, separating the prokaryotes (or cells without organelles -- no nuclei, no chromosomes, no mitochondria, no chloroplasts) from the eukaryotes (organisms like amoebae and paramecia, with all the complex parts contained in the cells of multi-cellular organisms). Prokaryotes include the amazingly diverse groups collectively known as "bacteria" and also the so-called "blue-green algae" which are little more than photosynthesizing bacteria, and are now generally know as Cyanobacteria.

All the earliest forms of life in the fossil record are prokaryotes -- or, loosely, "bacteria". In fact, more than half the history of life is a tale of bacteria alone. In terms of preservable anatomy in the fossil record, bacteria lie right next to the left wall of minimal conceivable complexity. Life therefore began with the bacterial mode. Life still maintains a bacterial mode in the same position. So it was in the beginning, is now, and ever shall be -- at least until the sun explodes and dooms the planet. How then, using the proper criterion of variation in life's full house, can we possibly argue that progress provides a central defining thrust to evolution if complexity's mode has never changed? [Life's mean complexity may have increased, Gould states, but he maintains that modes, not means, are the proper measures of central tendency in strongly skewed distributions such as the distribution of complexity in living organisms. You might have ten kids, nine with no money and one with a ten dollar bill, but that doesn't mean the average amount each kid has is one dollar.] The modal bacter has been life's constant paradigm of success.