You scratch my back and I'll scratch yours.

Filippo Simini is a postdoctoral research associate in the Center for Complex Network Research, led by Distinguished Univeristy Professor AlbertLászló Barabási. Photo by Mary Knox Merrill. Sup !pose you held in your hands a bunch of indi !vid !uals from dif !ferent species, sort of like a minia!ture Jumanji set. You have some cows, some bac !teria, some plants, some bugs, and a whole bunch of other living things. You throw the lot up in the air and let them land where they will, ran !domly posi!tioning them!selves next to one another.