Friday, 23 November 2012

Tim Tyler: Positional inheritance


Hi. I'm Tim Tyler, and this is a video about positional inheritance.

In universal Darwinism, copying is found ubiquitously in nature, from spreading ripples to propagating cracks, from growing crystals to scattering radiation. Copying - in conjunction with variation and selection - forms the basis of Darwinian evolutionary theory.

The copying in universal Darwinism includes DNA, culture, and a whole bunch of other aspects of the environment. To give some examples of environmental inheritance, rabbits inherit rabbit warrens, corals inherit their coral reef - and so on. The most common form of environmental inheritance is positional inheritance. To give some examples of this:

  • Raindrops - split and produce offspring that inherit their parents' position.
  • Cracks - have dividing tips and offspring crack tips start their lives near to their parents.
  • Atoms - split during nuclear decay - and the offspring particles originate near the parent atom.
Because of the property of physics known as locality, any form of inheritance is also accompanied by positional inheritance. That makes positional inheritance the most widespread form of inheritance in existence.

The products of positional inheritance often form tree-like structures. The roots and branches of plants resemble trees - and actually are phylogenetic trees of plant cells, laid down in order during development - in a combination of phylogeny and ontogeny. Similarly, lightning, propagating cracks, fractal drainage patterns, and crystalline dendrites are all associated with prominent visual trees. In each case, these are family trees, that show the path of descent. Sometimes the associated phylogenetic trees are less obvious. For example, in a landslide, each moving boulder has been pushed into motion by collisions with one or more parent boulders. Though each boulder can trace its ancestry back to the first falling stone, the resulting family tree is not obvious to casual observers. It's the same with raindrops in clouds and vortices in turbulent fluid flow.

Positional inheritance also results in adaptation - another hallmark of Darwinian evolution. Cracks adaptively seek the weakest path through matter, streams adaptively trace out the boundaries of their associated drainage basins and turbulence selectively forms where there is the most energy to feed it.

One thing that evolving systems typically need, in order to exhibit complex adaptations, is high-fidelity copying. Excessive noise often results in inherited information getting lost - and this leads to the disintegration of complex adaptations. However, positional inheritance often has pretty high fidelity - allowing complex adaptations based on it to remain stable.

Though positional inheritance is a pretty central concept in Darwinian evolution, it is a curiously neglected idea. While some seem to appreciate that organisms inherit their parents' environment as well as their genes, simple inheritance of position gets practically no recognition as a component of evolutionary theory. Sad times for Darwinism.


Note: This is an expanded version of a previous post on this topic. See also: velocity inheritance.

1 comment:

  1. Good point! It reminds me that I need to learn more about universal Darwinism. :)