Looks like a dead thread...
Hamilton's Kin Selection predicts sharing behavior based upon the relatedness of individuals in a population. It can be simply stated by c< b*r where c=cost, b=benefit and r=relatedness
Ultimately the cost of death could be considered to be equal to 1. Thus if a eusocial insect such as a bee dies in the defense of more than one of its sisters, the benefits in this case outweigh the cost since relatedness in bees is 0.75 and the benefit is 2 (1<2*0.75). So a bee would die to protect 2 or more of its sisters. This assures the passage of the original bees genes onto the next generation. (The genes are thus "selfish" in this case. They do not actually care for the individual bee's wellbeing as the bee is nothing more than a vehicle to carry on the particular gene in question.)
For species such as humans where the relatedness of siblings is 0.5, you would then predict that the action of dying to save your siblings would be expressed by 1<3*0.5...so a human could be predicted to give up his/her life to save 3 or more siblings. The process gets a little more muddied in small scale where siblings are generally related by more than 0.5 since the parents are likely to be cousins with relatedness of (on average) 0.125. In this case you can see that the full siblings are related to each other genewise by about .51 and thus when you apply Hamilton's Rule, you get 1<2*0.51 and thus in small scale societies, you would predict that people would be more altruistic towards each other.
Next, there's Triver's Reciprocal Altruism which can be stated by c< b*w where w=the perceived probablility of a payback. In this case you would most often have the costs be somewhat smaller, as in trusting a stranger to hold something of value for you while you go do something else.
So consider the constraints on altruism in real life, as in the scenario where an icecream truck is burning and instead of just one 12 year old...you have 2 and one of them is your nephew...which one to you save first? Hamilton's Rule predicts that you will first grab your nephew and then go back for the other child. It sounds heartless, but in many instances this is exactly the type of thing that happens. People will prefer to act in altruistic fashion with closely related individuals.
This message has been edited by Speel-yi, 02-04-2006 11:38 AM
™ Version 4.2
