EXAMPLE OF EVOLVING ARTIFICIAL LIFE FORMS

Phenotype:

body

type, x, y, z, width, height, depth of block 1

type, x, y, z, width, height, depth of block 3

type, x, y, z, width, height, depth of block 2

.... type, x, y, z, width, height, depth of block 9

brain

sensor1 excites neuron 1, weight 5

neuron1 excites neuron 6, weight 6

sensor2 excites neuron 2, weight 4

neuron2 excites neuron 4, weight 3

neuron2 inhibits neuron 5, weight 0

sensor3 excites neuron 3, weight 8

.... neuron 3 excites neuron 9, weight 4,

output of neuron 9 to muscle4

Genotype:

Chromosome 1

11

11010110

10101101

10101110

10011010

01101010

01101010

...

10001010

10001010

10001010

type1

xpos 1

ypos 1

zpos 1

width 1

height 1

depth 1

...

width 9

height 9

depth 9

Chromosome 2

0000

10

1001

1

0110

1

...

1110

neuron1 marker

neuron1 type (in/intl/out)

neuron1 link1

neuron1 link1 type (ex/inhib)

neuron1 link2

neuron1 link1 type (ex/inhib)

...

neuron9 link2

Figure. Evolutionary Artificial Life Form.

To illustrate this type of Evolutionary Design, we return to the 'table' example one final time. However, instead of a static table, we now require a robot / virtual creature / animat capable of carrying objects around - a robot waitor, perhaps. The figure shows the dual nature of these designs: Evolutionary AL-Forms typically involves the evolution of the form (or some aspect of the form) and the brain. In this example, the form, or 'body' is defined by a collection of variable-sized blocks (which may be 'sensors', 'body' or 'muscles'), the 'brain' is defined by a network of neurons which receive input from 'sensory blocks' and produce output to the 'muscle blocks'. Each part of the phenotype is encoded as a variable-length chromosome in the genotype. The fitness function judges phenotypes on their ability to move whilst keeping the flat upper surface level. Over time, evolution will co-evolve both chromosomes in individuals to generate a virtual creature capable of supporting objects and movement in a virtual world.