Can you explain to me what is basically meant by "selfish genes/chemicals"? Is it just giving a catchy label to something that doesn't really have anything to do with "being selfish"? Or is there more to it? Why was the label 'selfish' chosen to describe such things?
Selfish genes was just chosen as a eye catching title for a pop-sci book. As is often the case in science, catchy names stick - even if they cause confusion. The pupose of the book was to explain
selfless behaviour in individuals with regards to evolution as the behaviour of utterly selfish behaviour of genes.
It's a good book - worth checking out (and the most recent version has a pile of footnotes with up to date info and expansions on those sections and terms people had apprehensions about over the thirty years since it was first published.
The basic thesis is that genes do whatever they can to replicate. Almost all of the time this has the side effect of benefiting the individuals that inherit them, and some times it has the side effect of benefiting the populations that are composed of individuals that have inherited them. But no matter how selfless the populations or the individuals...the genes remain entirely and completely 'selfish'. They only 'care' about getting themselves replicated.
I think that the point is particularly saliently demonstrated with intragenomic conflict: sometimes, and seemingly paradoxically, the genes manage to increase in frequency even though they are, on the whole, detrimental to the health or wellbeing of the individual that possesses them.