Lecture 6 ANTH 170c1 Outline of Last Lecture I Types of Social interactions II Altruism III 1st Kins Selection IV The reproductive success of a gene V Theory of Kin Selection VI W d Hamilton Outline of Current Lecture I Altruism II W D Hamilton III Why Kin Selection revolutionized our thinking IV Behavioral tendency is not he comprehension of selective benefits V Requirements for Kin Selection VI 2nd Evolutionary explanation for altruistic behaviors VII Examples of reciprocity VIII The group selection fallacy IX Cooperative behaviors and reproductive fitness X Does group selection occur XI Group Selection conclusion Current Lecture Title Kin Selection I Altruism A The apparent cost to the donor and benefit to the recipient B Hard to explain why this would be selected for II W D Hamilton A rb c B E g if the receiver is a full sibling r 0 5 III Why kin selection revolutionized our thinking A Before we didn t understand why all the seemingly costly behaviors were not selected out of the population B In theory vs in practice 1 In the abstract great 2 Practice very difficult to task IV Behavioral tendency is not he comprehension of selective benefits A selection for behavior does not require that an individual understands that ad aptive value of behavior V Requirements for kin selection A Interaction with kin B Is ti necessary to be able to recognize kin 1 If both kin and non kin are present individuals better able to distinguish kin And preferable direct benefits towards kin will tend to pass on more genes nd VI 2 Evolutionary explanation for altruistic behaviors A repeat interactions over time B the ability to keep track of interactions C provide support conditionally to those who support them in return 1 otherwise will get taken advantage of decreased fitness VII Examples of reciprocity 1 baboons and fighting partners 2 capuchin food sharing VIII The group selection fallacy A Also known as the species benefits B the idea that behaviors that help a species survive at a cost to the individual should be adaptive Natural selection nonrandom differential reproductive success IX Cooperative behaviors and reproductive fitness A Help kin can pass on more genes X Does group selection occur A Almost never the best explanation for behaviors B Requires conditions that are very rare XI Group Selection conclusion A Individual and kin selection are generally better explanations as to why a traits is ad aptive B Challenge try to think a behavioral trait that requires group selection because it can t be explained by individual selection such as reciprocity or kin selection