> So you don't have to be convinced that any given species will expand, just accept that some might. You'd have to accept the other assumptions that the author

> So you don't have to be convinced that any given species will expand, just accept that some might. You'd have to accept the other assumptions that the authors make as well. One is that the grabby species is capable of travelling at a significant fraction of lightspeed. Another factor is unlimited lifetime of civilisations. > Expansion is selected for in biological evolution, so it's fair to assume that most pre-civilization species are expanding on their planet. Hm. I'm not sure that biology is the right angle to approach this. There are plenty of examples in human history (and even today) where expansion was not at all favoured by civilisations and human communities. Isolated tribes on islands and in rain forests are a counter-example, as well as isolationist phases of civilisations such as feudal Japan in the Edo period. To me the model is basically just another hypothesis based on the Spherical Cow.