Ulla Mattfolk they aren’t separate today.
However, it is reasonable that many of their early evolutionary behaviors will remain.
For example, the gene expressions of neurons may be more specialized now but were probably more multipurpose in their evolutionary past.
So it might be worth asking if some of the genes currently can be more expressive in some situations than give credit for.
So if we study evolutionary cousins, we may find certain behavior that we may have been interpreting in a purely physical manner may be the result of individual or collective intelligent behaviors.
That is, perhaps neurons “make us smart” because groups of eukaryotes are smart.