by Simon Fraser

What is it?

Tierra aims to study the evolutionary process by the instantiation of evolution in another form, namely in an ecosystem of interacting and competing machine code programs living in the Tierra environment, which emulates a massively parallel computer.

MacTierra is an independent implementation of Tierra, written largely without knowledge of the original Tierra code, but following descriptions of the system given in publications. It is thus, in some sense, an attempt at verifying the results of the original Tierra. Howerver, much effort has been put into the user interface, to make it easier to use, and thus more accessible to people. In addition, it will, in time, diverge from Tierra in the details.


MacTierra aims to present the user with a highly interactive interface, so that simulations can be studied as they are running, saved to a file and restarted later, and the activities of the creatures within them closely monitored. Full use is made of features of the Mac OS, such as Drag and Drop, to facilitate moving creatures around and examining them as they execute instructions.

This makes it very easy to devise and execute a multitude of interesting ecological experiments, and to study the evolution of the system as a whole over time. There is much potential in Tierra-like systems to learn about ecological and evolutionary processes.


You can read the documentation for MacTierra online, which are identical to the docs you get with the distribution.


MacTierra 1.0 for Mac OS X is now available.

MacTierra for Mac OS 9 and earlier is no longer available.

Source Code

Source code for MacTierra is available on Github. It requires Mac OS X 10.5 (Leopard), and developer tools to build.