Playing With Evolution In Artificial Life

Posted February 17, 2015 by Joshua Nahum in Information, Review / 3 Comments

One of my stepping stones towards becoming an evolutionary biologist was playing with engaging programs that combine evolution and artificial life. Although these “games” are often neither intended for educational or research purposes, I found them instrumental in developing an appreciation for the power and creativity of evolution by natural selection. Here is a collection of my favorites in no particular order:

The body plan for an organism from the Bitozoa program.
The body plan for an organism from the Bitozoa program.

The Bitozoan program models the evolution of both herbivores and carnivores in a simplistic 2d world. The organisms evolve more complicated behaviors using their eye sensors, neural net, and flagella. In tens of minutes, you can see the emergence of cautious herbivores, ambush hunting by carnivores, and territorial behavior. There are dozens of parameters to play with that affect the evolutionary trajectories of both species!

Disney meets Darwin
Disney Meets Darwin - Watch and participant in the evolution of gaits (types of walks)
Disney Meets Darwin – Watch and participate in the evolution of gaits (types of walks)

This is a simple in-browser program to watch the evolution of gaits. After a few minutes of selecting the best walkers (either manually or by a set of criteria), the population will be able to move at an appreciable speed. When that loses its excitement, you can adjust the body plan to add more legs or art style. A nice diversion for ten minutes.

Gene Pool – Swimbots

Swimbots is a simulation of hundreds of “swimmers” living in a 2d world. They eat spontaneously generated food particles by swimming in close proximity to them. Swimmers can also mate with each other, provided they have accumulated enough energy (from eating). Each organism’s body plan and swimming style is genetically determined. In addition to the need to be an agile swimmer, each organism has a sexual preference that determines what they find attractive and will seek to mate with. By adjusting what criteria the swimmers prefer, you can watch the evolution of very different organisms. Often, you can observe speciation happen. A very fun and addictive game.

Primordial Life
A population of organisms in Primordial Life (from
A population of organisms in Primordial Life (from

In this 2d world, organisms are composed of symmetrically placed line segments, the color of which determines its function. Green segments generate energy from the sun’s radiation. Red segments consume other organism’s line segments, and hence generate energy in a predatory manner. Dark blue are armor, light blue provides motility, and other segments allow for sexual recombination. A fun simulation that can demonstrate the diversity of forms natural selection can generate.

Screenshot from Darwinbots.
Screenshot from Darwinbots.

Darwinbots is the most complex of evolving worlds on this list. Organisms are composed of cells that can bind together to form multicellular creatures that can both be herbivores and carnivores. They can eat each other in two ways: by spitting digestive enzymes, or binding and sapping energy directly. They can generate motile force, or rely on the jostling of others. Often, I add two different species and compete them to see how they adapt to each other. Evolution is particularly slow in this complicated world, and population sizes are often small. But if you are willing to devote the time, Darwinbots can be quite enjoyable.

Image Evolution
Image of Darwin, composed of 50 polygons, selected by their similaity to a portrait of Darwin.
Image of Darwin, composed of 50 polygons, selected by their similarity to a portrait of Darwin.

This website allows you to select a photo to be the target of evolution. After clicking start, a random image composed of dozens of polygons appears. The location of vertices or the color of a polygon is mutated, and if the new polygon-composed image better matches the target photo, it becomes the new best (from which mutants will be generated). In seconds, patterns from the target photo will be represented by the massed polygons. Although this website doesn’t have populations and other biological similarities, it still provides a nice demonstration of the power of combining selection with mutation.

Avida ED

Avida ED is the educational version of the Avida platform that our lab uses for research. It is simplified and contains an colorful user interface that lends itself to both education and play. Like Avida, organisms are simple computer programs that can evolve to perform tasks that enable access to faster growth. Over the course of minutes, you can witness the spread of organisms containing beneficial mutations that increase their competitive ability. By changing parameters like mutation rate or which tasks are rewarded, you can watch different evolutionary scenarios take place. As Avida ED is under active development, we hope to see new and engaging features added as more students and teachers use Avida in their classrooms.

That’s all from me! If you have found other fun systems demonstrating evolutionary principles, let me know in the comments.

Joshua Nahum

I am a postdoc in the Ofria Lab and BEACON, with an interest in the interplay between environments and the organisms that evolve there in. I'm also an enthusiast in computer science and software development, despite my PhD in Biology.

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3 responses to “Playing With Evolution In Artificial Life

  1. I also like following:

    boxcar2d and its HTML5 clone – Evolves cars made up of polygons connected to wheels by selecting the ones that go farthest along a randomly generated track. The simulated physics makes this a very fun one to watch. The HTML5 clone has a number of cool additional features, such as allowing you to alter the gravity of the environment. also has a fun example of evolving bipedal walkers by selecting the ones that go the farthest.

    Picbreeder is another fun system in which you get to select images to serve as parents for the next generation. People have managed to evolve a number of interesting pictures, both representational and abstract. BEACON even hosted a competition on Picbreeder to see who could evolve the best lighthouse.

    The Ladybug Game is also a fun and accessible demonstration of natural selection, more aimed towards kids. It clearly illustrates the three ingredients necessary for adaptive evolution and how if they are all present adaptive evolution will occur. For a more thorough description, see this post on the BEACON blog.

  2. Hey Josh, great writeup!

    As someone who has been diving into artificial life a lot in the last year, this and other recent posts are right up my alley.

    You might be interested in checking out some of the a-life visualizations I’ve built at There are currently 10 mini-projects (and more on the way) and they’re all done in JavaScript so you can check them out right in your browser.

    I’m looking forward to exploring these other sites – thanks!


    • Thanks Matt,

      Emergent Mind does indeed look interesting. And I must confess, “Forming a Planet” consumed more time in fiddling with than I’d like to admit. I’ll be keeping an eye on what you do in the future.

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