From Bacteria to Bach and Back

Part I: Turning Our World Upside Down

1. Introduction

• How come there are minds?
  • Minds evolved and created thinking tools that eventually enabled minds to know how minds evolved, and even to know how these tools enabled them to know what minds are.
  • What thinking tools? The simplest, on which all the others depend in various ways, are spoken words, followed by reading, writing, and arithmetic, followed by navigation and mapmaking, apprenticeship practices, and all the concrete devices for extracting and manipulating information that we have invented: compass, telescope, microscope, camera, computer, the Internet, and so on.
  • These, in turn, fill our lives with technology and science, permitting us to know many things not known by other species. We know there are bacteria. Even bacteria don't know there are bacteria.
  • Our minds are different. It takes thinking tools to understand what bacteria are, and we're the only species (so far) endowed with an elaborate kit of thinking tools.
• A birds-eye view of the journey:
  • Life has been around on Earth for around 4bn years. The first 2bn were spent optimizing the machinery for self-maintenance, energy acquisition and reproduction, and the only living things were relatively simple, single-celled entities - bacteria or their cousins, archaea: the prokaryotes.
  • Then an amazing thing happened. Two different prokaryotes collided and instead of one eating the other, it let it go on living, and, by dumb luck, found itself fitter, more competent in some way that mattered, than it had been before. This was perhaps the first successful instance of technology transfer. A fortuitous mutation almost never happens, but evolution depends on those rarest of rare events. This is the birth of the eukaryotes
  • Every living thing big enough to be visible to the naked eye is a multicellular eukaryote.
  • The Cambrian Explosion, which occurred over several million years about 530m ya, saw the sudden arrival of a bounty of new life forms.
  • The "MacCready Explosion", at the dawn of human agriculture, about 10k ya, transformed the terrestrial vertebrate biomass (excluding insects, other invertebrates, and marine animals). At the beginning, humans plus their livestock and pets make up only 0.1%, and now we make up 98% (mostly cattle). This explosion is based on three factors - population, technology, and intelligence (our so-called native intelligence depends on both our technology and our population numbers).
• Dennett identified the "romantic" and "killjoy" sides of the duel over the stature of animal minds. We are not the God-like geniuses we think we are, but animals are not so smart either, and yet both humans and other animals are admirably equipped to deal "brilliantly" with many of the challenges thrown at them.

2. Before Bacteria and Bach

• until there were systems that could be strictly called reproducing systems, the processes at work were only proto-evolutionary, semi-Darwinian, partial analogues of proper evolution by natural selection; they were processes that raised the likelihood that various combinations of ingredients would arise and persist, concentrating the feedstock molecules until this eventually led to the origin of life.
• A living thing must capture enough energy and materials, and fend off its own destruction long enough to construct a good enough replica of itself.
• The reverse-engineering perspective is ubiquitous in biology and is obligatory in investigations of the origin of life. It always involves some kind of optimality considerations: What is the simplest chemical structure that could possibly do x? Or would phenomenon x be stable enough to sustain process y?
• Orgel's second rule: "Evolution is cleverer than you are."
• Here is an example of a possible gambit in the origin of life:
  • It is tempting to assume that the very first living thing capable of reproducing must have been the simples possible living thing (given the existing conditions on the planet at the time).
  • Make the simples replicator you can imagine and then build on that foundation.
  • But this is by no means necessary. It is possible, and more likely, I think, that a rather inelegantly complicated, expensive, slow, Rub-Goldberg conglomeration of objets trouvés was the first real replicator, and after it got the replication ball rolling, this ungainly replicator was repeatedly simplified in competition with its kin.
  • Many of the most baffling magic tricks depend on the audience no imagining the ridiculously extravagant lengths magicians will go to in order to achieve a baffling effect. If you want to reverse-engineer magicians, you should always remind yourself that they have no shame, no abhorrence of bizarre expenditures for tiny effects that they can then exploit. Nature, similarly, has no shame - and no budget, and all the time in the world.
• Adaptionism is alive and well; reverse-engineering is still the royal road to discovery in biology.