Arnold Toynbee attributed the fate of Sparta to excesses of specialization. In making his point, Toynbee invoked the dystopian novels of the day, writing of Huxley’s Brave New World, and Wells’ First Men on the Moon, both of which feature dehumanizing degrees of specialization. He does not neglect to compare human excesses of specialization to complex insect societies, drawing parallels between insect castes and the human social engineering that constrains the specialist. At the time, it was believed to be the nature of social insect instincts to be exquisitely adapted, but perfectly inflexible. In human affairs, Toynbee warns, “from such inflexibility it is a short step to folly” (Toynbee, A study of history, 1951; volume I). Policies, intelligently designed procedures, instructive mannerisms, and productive practices of all kinds can become instilled into a society long after their original object has disappeared. Inertia of rigid forms results. In this ninth chapter, Sparta is discussed as an archetype of the extremely group-selected society and analyzed empirically so as to ascertain whether, as Toynbee asserted, martial specialization cut both ways, first creating Sparta’s legendary power, and then undermining Sparta’s continued competitiveness. Although there might be some historical validity to Toynbee’s position, this single explanation is incomplete. We examine the analogy to social insect societies in greater detail and determine whether and to what extent it is predictive of the rise and fall of Spartan military success over the span of several centuries. Nevertheless, we will also examine certain confounding biodemographic factors as alternative, if not mutually exclusive, hypotheses.