Lions

Lions serve as a recurring case in The Selfish Gene for examining how apparently social order and interspecies conflict can be explained through gene-centered selection. They are predators whose interests conflict with those of antelopes, members of prides whose average relatedness can be estimated, and males that may kill cubs fathered by others. Across these examples, the book treats behavior not as service to a species or group, but as the outcome of strategies shaped by their consequences for genes carried by individuals.

Predation and interspecies conflict

The book frames a lion's pursuit of an antelope as a conflict over the same physical resource: meat. The lion's genes benefit when meat serves as food for the lion's survival machine; the antelope's genes benefit when that meat remains part of the antelope's working muscles and organs. Those uses cannot coexist. Predation is therefore not merely a contest between different species in the abstract, but a direct clash between incompatible interests in the antelope's body.

The contrast with conflict among members of one species clarifies the argument. Lions do not normally hunt adult lions for food, the book argues, because a cannibal strategy would be evolutionarily unstable: the target can retaliate, making the danger too great. Such a balance is less likely between species, where differences between contestants can make the encounter asymmetrical. In the lion–antelope relationship, evolutionary divergence has heightened that asymmetry: lions have become proficient at pursuit and antelopes at escape. An antelope that stood and fought would fare worse than rivals that ran.

This example makes escape a conditional strategy rather than evidence that prey simply accept a predator's advantage. When contestants differ in consequential ways, strategies can depend on those differences. The lion and antelope illustrate how opposing adaptations may settle into a form of stability, even while their interests remain sharply incompatible.

Prides and the estimation of kinship

The discussion of lions also turns from predation to the structure of a pride. Drawing on Brian Bertram's long study of lions in Serengeti National Park, the book describes a typical pride as having seven more permanent adult females and two itinerant adult males. About half the females give birth at the same time and rear their cubs together, making it difficult to tell which cub belongs to which mother. A typical litter has three cubs, and the two adult males share fatherhood equally. Young females remain in the pride, replacing older females who die or leave; adolescent males are driven out and later wander between prides in small related gangs or pairs, unlikely to return to their original family.

These details matter because they make a pride's average relatedness calculable even when the relationships of particular lions are uncertain. Bertram estimated that two randomly chosen males in a typical pride have an average relatedness of 0.22, while two females average 0.15. The first figure is slightly below the relatedness of half-brothers; the second is slightly above that of first cousins. Particular lions may be full siblings, but the available evidence does not establish that for any randomly chosen pair, and the book cautions that the lions may not know exact relationships either.

The proposed evolutionary consequence is calibration to the average, not perfect recognition of each relative. If pride life has remained sufficiently consistent over many generations, a gene that predisposes males to treat other males as nearly half-brothers could be favored. A disposition that is too generous, as though all were full brothers, or too ungenerous, as though they were more distant kin, could be penalized. On this account, selection can produce behavior appropriate to the typical degree of relatedness without requiring lions to calculate family trees.

Kinship, rules, and social categories

The lion example belongs to a broader account of how relatedness can inform altruism. The book offers a practical way of estimating relatedness by identifying recent common ancestors and counting the generational steps up to an ancestor and down again to the other individual. It notes that this rough method works in simple cases but breaks down in cases involving incestuous mating and in certain insects. Such calculations provide a framework for thinking about how a gene associated with care or sacrifice might persist through relatives who carry copies of it.

Parental care is presented as one form of kin altruism, not a genetically unique duty. An adult is related to its own child and to an orphaned younger sibling by the same proportion, one half. In gene-selection terms, a disposition to care for a younger sibling could therefore spread as a disposition to care for one's own child could, although the book stresses that this is an oversimplification and that sibling care is much less common in nature than parental care. The distinction is between who receives the care and how relatedness bears on the gene's prospects, not between two fundamentally different kinds of genetic benefit.

For humans, kinship is also a cultural and social category. People identify relations through names, marriage, written records, and memory; kinship customs and family obligations shape social life. The book interprets blood-feuds and inter-clan warfare as readily understandable through genetic theory, while treating incest taboos as presumably connected not to altruism but to the harmful effects of recessive genes appearing through inbreeding. It also warns against treating social kinship and genetic kinship as identical: cultural ideas and institutions help establish who counts as family and what obligations follow.

Care, adoption, and paternal conflict

The book's account of adoption distinguishes apparent care from demonstrated genetic benefit. In groups, an orphan may be adopted by a female who has lost her own young; observers sometimes call such an adopter an aunt, but the label does not establish that she is actually related. The book suggests that some adoptions may be a misfiring of a rule that usually directs care toward kin: an unrelated adopter may spend time and energy that could have gone to her own relatives or future offspring. The account also notes that many orphans are not adopted and are left to die.

A more striking possibility is the bereaved female that steals another female's baby and cares for it. The book calls this a possible double mistake: the adopter invests in a child that may not carry her genes, while the birth mother is freed from the burden of care and may reproduce again sooner. But it does not present the explanation as settled. It identifies unanswered questions about how often the behavior occurs, the likely relatedness of adopter and child, and the birth mother's response, including whether mothers might deceive inexperienced females into adopting their young. The episode is thus framed as a case demanding investigation, not as decisive evidence against gene-centered theory.

Male lions provide another instance of conflict over parental investment. Newly arrived males in a pride sometimes kill existing cubs, which the book presents as presumably connected to their not being the males' own offspring. This example sits alongside the broader discussion of deserted females and potential step-children: a new male may benefit reproductively if a female is no longer raising another male's young. The proposed explanation concerns conflicting reproductive interests; the account does not establish that every new male behaves this way or that the behavior has only one cause.

What the examples establish

The lion material connects several scales of analysis without treating the group as an agent with a single interest. Predation reveals conflict between the uses different species make of the same resource; the stability of avoidance and escape turns conflict into conditional strategies; pride structure supplies a basis for estimating average kinship; and adoption and infanticide show how care can be entangled with reproductive costs and competing interests. The examples support a gene-centered way of posing questions, while the book distinguishes proposed interpretations from established observations and flags cases where more evidence is needed.

The broader argument is not that lions consciously calculate genetic returns, nor that apparent care must always be a disguised calculation. Behavioral rules can have consequences for gene survival without an animal knowing the relevant kinship or evolutionary history. In this account, the pride's social pattern is not explained by an independent benefit to the group: it is analyzed through the different strategies individuals may adopt and the conditions under which those strategies persist.