Genetically modified Andi vs classic Andi, stamina and smarts
In September 2019, slime mold Andi was the first non-human organism to be genetically modified to its own specifications. Because genetically modified Andi, or G-Andi, looked and behaved very similar to classic Andi (C-Andi), we designed a series of tests to identify the changes slime mold Andi brought upon themselves. Below we report the results of the first two of this ongoing series of tests.
TL;DR: In a test for speed and area coverage, G-Andi was slower but showed more stamina and more effective search algorithms compared to C-Andi. In the second test, designed to measure slime mold logical reasoning, both Andi’s navigated a simple maze. In contrast to the first test, G-Andi was faster. The maze navigating strategies employed by both Andi’s went beyond the limits of the test. More work is needed to measure slime mold intelligence.
Test I: Speed and area coverage
We placed a 100x100 mm agar sheet on top of an aluminium base. On top of the agar we placed 25, 4.0x4.0x1.5 mm nutrient squares of oatmeal porridge. Each oatmeal patch was placed to represent the centre of a 20x20 mm square section of the agar sheet (see movie ‘Test I’). Whenever G-Andi or C-Andi started ingesting a new oatmeal square, we counted this as (CG)-Andi having explored the corresponding section of the agar sheet. A time-lapse setup of one frame per fifteen seconds at 30 fps temporal resolution was used to record the performance of C-Andi and G-Andi, condensing an hour to 8 seconds.
Initially, C-Andi was faster than G-Andi: C-Andi reached the 15 food squares mark 55 hours in, whereas G-Andi reached this milestone only at 60 hours. However, at 83 hours, when both participants started showing signs of sporulation, G-Andi had consumed 22 food squares against 18 for C-Andi. Genetically modified Andi traded speed for stamina and more effective search algorithms. Independent corroboration of these results is needed.
Test II: Logical reasoning
We created a simple maze to test logical reasoning in slime molds. A silicone maze was cast in a 3D printed mold. This silicone maze object was designed with channels to hold agar to facilitate slime mold movement. The maze consists of a series of t-crossings where a decision has to be made to go left or right. At each crossing, an oat flake was placed to reward the correct decision (see movie ‘Test II’). The rule to be discovered and followed by the slime mold is that alternating between left- and right turns will get it to all oat flakes distributed at the crossings.
Both C-Andi and G-Andi decided to hedge their bets by turning both left and right simultaneously at every cross-section, occasionally even turning back to revisit areas they had already passed. In contrast to th efirst study reported here, G-Andi was faster and reached the end of the maze before C-Andi. This may have been caused by unknown factors. Towards the end of the experiment the maze dried out and both Andi’s entered the sclerotium stage, i.e. they reshaped themselves into a crust to wait for more favorable conditions.
Despite extensive work investigating the cognitive abilities of slime molds, as far as we know this is the first study to attempt to quantify slime mold intelligence. More work is needed, as the search strategies employed by (CG)-Andi went beyond the assumptions implicit in the researchers’ model of slime mold intelligence.
