The Genetical Evolution of Social Behaviour 2 on Superphysics

Mon, 01 Jan 0001 00:00:00 +0000

Grounds for thinking that the model described in the previous paper can be used to support general biological principles of social evolution are briefly discussed.

Two principles are presented, the first concerning the evolution of social behaviour in general and the second the evolution of social discrimination. Some tentative evidence is given.

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

In the previous paper (Hamilton, 1964) a genetical mathematical model was used to deduce a principle concerning the evolution of social behaviour which, if true generally, may be of considerable importance in biology. It has now to be considered whether there is any logical justification for the extension of this principle beyond the model case of non-overlapping generations, and, if so, whether there is evidence that it does work effectively in nature. In brief outline, the theory points out that for a gene to receive positive selection it is not necessarily enough that it should increase the fitness of its bearer above the average if this tends to be done at the heavy expense of related individuals, because relatives, on account of their common ancestry, tend to carry replicas of the same gene; and conversely that a gene may receive positive selection even though disadvantageous to its bearers if it causes them to confer sufficiently large advantages on relatives.

Mon, 01 Jan 0001 00:00:00 +0000

just previously. Now, using other examples, we indicate some other kinds of argument which it may be useful to apply to these situations.

CO-OPERATION

In certain ants, notably Lasius flavus and L. niger (Waloff, 1957), it is known that companies of several queens will cooperate in excavating the initial nest. Since these have just come to earth from a vast mating-flight they are un- likely to be close relatives. According to Waloff, the queens of L. flavus usually cohabit peacefully in the nest-chamber and even keep their eggs in a common pile, but about the time cocoons are first formed they tend to separate, some taking a portion of the brood (not necessarily a very fair one it seems) to a particular corner of the nest. There is evidence that the queens so separated tend to control distinct sectors in the developing nest, each having its own worker population; and whether by death of queens-by fighting or otherwise or by migration of a “sector”, most nests of L. flavus end up haplo- metrotic. In L. niger fighting between the queens is regular and generally only one survives in the initial nest chamber.