Yup. That's it. That's everything explained right there.
Where "r" is relatedness...how closely genetically related you ( the subject) are to the recipient (object) of your kindness...
"B" is the benefit this cousin of yours acquires from your sacrifice...
Then if the product of these two is greater than (>) the cost (C) to yourself of that sacrifice or expenditure of energy...
Then you won't eat your grandson at Christmas instead of getting him a book token.
Or, if you're a drone bee or worker ant, it's why you will still contribute to the hive when you aren't, personally/reproductively speaking, going to get anything out of it. You may die but your genes will thrive. To put it yet another way, all social (or familial) behaviour is really nepotistic survivalism in disguise.
This equation was Bill Hamilton's way of accounting for selfless behaviour within the "selfish" paradigm of Darwinian Nature. He came up with it in the sixties, and it's still quite popular.
It's an early highlight for me in my current reading for this project, which is Oren Harman's biography of George Price "The Price of Altruism".
(See that clever thing he did there with the title?)
The first part of the book sets the scene for Price's own work...and strange demise...by an historical survey of the various ways that various minds have tackled this paradox, from Kropotkin's Anarchistic reading of nature as modelling "Mutual Aid" as the answer to all our problems, to the neo-liberal free market in genes offered by Dawkins et al that is our current orthodoxy.
(I know whose side I WANT to be on...I know who I WANT to be right)
But it begs the question - do we really read nature as it is, or do we map our desires and values onto it? Like we used to do...still do...with God? Isn't the word "nature" itself an instance of that?
And a further maybe broader question...which I think will be the theme of our next gathering in the Traverse Bar
(Thursday July 28th 2pm to 4pm- be there or be excluded from kinship selection) -
Can Understanding Nature Ever Tell Us How to Be Good?
I'll try to dig up some interesting stuff to look at...meanwhile, here's some bees.