isolation reveals the true natures of the students as individuals, but it also demonstrates some of the constants of human existence as a social animal. Its underlying themes run counter to those in Lord of the Flies, however, in that it shows a belief in the inherent strength of humans as proto-adults who can self-organize rather than descend into barbarism. Some of the students fall victim to their own foolishness, and others turn out to be thugs, but that is a part of human nature, just as the counter-trends take the group as a whole towards the beginnings of a stable society. The numerous political crises of the fledgling colony illustrate the need for legitimacy in a government appropriate for the society it administers, another common theme in Heinlein's books. In both its romanticization of the pioneer and its glorification of Homo sapiens as the toughest player in the Darwinian game, it presages themes developed further in books like Time Enough for Love and Starship Troopers. Unusual for science fiction at the time, but quite typical of Heinlein's works, the novel portrays several competent and intelligent female characters. The earlier part of the book makes a reference to a war - some generations before the book's plot begins - in which China conquered and colonized Australia. The remnants of Australia's original population - evidently referring to both Aboriginal Australians and European-descended Australians - were evacuated to New Zealand. The Chinese then engaged in a giant engineering project to reclaim Australia's central desert, but it soon became a vast overpopulated slum. In the book's present, the Chinese are colonizing marginal planets with harsh conditions, which nobody else wants, miserable peasants forced to move there against their will. All that has little bearing on the book's main plot, serving mainly to demonstrate the strong Malthusian pressures which inflicted Earth until the way to colonize other planets by matter transmitter was found. Rod's ethnicity Heinlein Society member and researcher Robert James has noted that Heinlein wrote a letter in which he "firmly states" that Rod Walker is black. According to James, "The most telling evidence is that everybody in 'Tunnel' expects Rod to end up with Caroline, who is explicitly described as black." In recognition of this, the cover illustration of a Full Cast Audio version of the work was revised to "show Rod with his correct ethnicity." Rod is at one point