Posts Tagged «cognition»

The evolution of cognition is the story of an ever accelerating fitness optimization process. A short introduction can be found in my paper on friendly AI theory and a longer explanation is provided in Valentin Turchin‘s book – The Phenomenon of Science.

Applying metasystem transition theory the evolution of cognition can be understood as having went through the following stages:

  • position
  • movement controls position
  • simple reflex controls movement
  • complex reflex controls simple reflexes
  • associated learning controls complex reflexes
  • imagination controls associated learning
  • conscious thought controls imagination
  • beliefs control conscious thoughts
  • charisma and science control beliefs

The roots of our animal urges – such as cravings for cheeseburger with fries – have probably evolved on the level of the complex reflex in a scarce caloric reality. So what is keeping (some of) us from constantly overindulging and satisfying this and other animal urges? It is of cause our realization that overeating – once necessary to prevent starvation should the next harvest not go so well – will not be worth the negative side effects in our post caloric scarcity society.

Our beliefs such as ‘overeating is bad for me’ are controlling our lower level complex reflexs such as ‘must eat good food’ and so we diet and exercise. That’s how evolution has put mind over matter – easy as pie.

As touched upon earlier genetic evolution is complexity bound. To be exact to about 25 megabytes because roughly speaking, genetic evolution isn’t going to support more than 10^8 meaningful bases with 1 bit of selection pressure and a 10^-8 error rate.

Reflecting on this complexity boundary in genetic evolution I was wondering what cognitive evolution’s complexity boundary might be in humans. As basis I will assume that:

1) cognitive evolution in humans is taking place on the level of beliefs (a brief summary can be found in my paper on friendly AI theory)

2) beliefs are stored in the neural structure of the brain

3) the informational complexity of the neural structure of the brain that stores beliefs is equal to cognitive evolution’s complexity boundary in humans

Being a friend of Google I quickly came across this interesting estimate of the informational storage capacity of the human brain:

“The human brain contains about 50 billion to 200 billion neurons (nobody knows how many for sure), each of which interfaces with 1,000 to 100,000 other neurons through 100 trillion (10 14) to 10 quadrillion (10 16) synaptic junctions. Each synapse possesses a variable firing threshold which is reduced as the neuron is repeatedly activated. If we assume that the firing threshold at each synapse can assume 256 distinguishable levels, and if we suppose that there are 20,000 shared synapses per neuron (10,000 per neuron), then the total information storage capacity of the synapses in the cortex would be of the order of 500 to 1,000 terabytes.”

Staying on the safe side I will assume that this estimate is off by two orders of magnitude and that only one percent of the human brain is actually involved in storing beliefs. As a result I estimate that human cognitive evolution on the level of beliefs is bound by a complexity of no less than 100 gigabytes or at least 4’096 times higher than that of genetic evolution.

Evolution – meaning the process of chance mutation and non-chance retention by natural selection – is a slow, tedious and complexity bound process on the genetic level as pointed out brilliantly by Eliezer on the overcomming biases blog. Genetic evolution as an optimization process is full of flaws, drawbacks and dead ends. Genetic evolution is blind and if genetic evolution has a goal it can only be seen in the implicit goal of increasing fitness.

Human cognition is a far better optimization process, yet by far not as well understood as genetic evolution. The crucial point of genetic evolution however is, that it is the only naturally occurring optimization process. Having taken 3.5 billion years to evolve the superior optimization process of human cognition one might argue that genetic evolution has done its duty and can retire and leave increasing fitness further to its successor: human cognition.