They actually did implement what they needed straight into the genome,
3.4 Implementation details
For the environment generation the following tools were used: Creatures Map Editor
1.08 for the world edition, gimp to develop .bmp images, and sprite builder to convert
them into the frame format. Creatures or agents living in the virtual world are
composed of images, scripts and genome. Since our goal was not to develop a new
world for entertainment purposes but to study social interactions between agents, we
have used already developed creature images obtained from Creatures 3. To develop
creatures’ behaviour, scripts were modified by adding new actions and behaviour
rules described above. For implementation, CAOS (Creatures Agent Object Script)
1.002 and Creatures Engine 2.286, which enable the execution of our world in
Creature 3 and Docking-Station were used. The creatures’ brains (neural network)
and their biological structure defined by the genome (.gen) were generated using
Genetics kit for Creatures 3 1.16.4 enabling adding initial knowledge, states, goals
and actions.