Survival of the fittest
At its core Pandorum is post-apocalyptic science fiction centering around ecology and methods of survival. Ecology is the study of interaction among organism and their environment with topics of interest is the number of organisms(population), competition between them, evolution, adaptive behavior, and predation. As one of the characters state "It's just survival of the fittest...Or maybe it's the brightest", a phrase is widely used as a catchphrase for any topic related to evolution by means of natural selection. It has also be used as a synonym to other dialogue mentioned in the film such as "every man for himself" and "dog eat dog" both which describe egoistic competitive situations. They're all summed up as the The Law of the Jungle which some believe should apply to humans believing that social process resulted from conflicts in which the fittest or best adapted individuals, or groups, would prevail. Such a philosophy is referred to as Social Darwinism. Earth was overpopulated causing humanity to try and establish civilization on Tanis to ensure survival. Paranoia is a survival mechanism as its the fear of potential threats, that and with accelerated evolutionary survival of the fittest created a species with troglofaunal adaptations and characteristics such as albinism and heightened sense of smell due to the ship's low sunlit environment that live by the ideological form of survival of the fittest.
Its not just these creatures who are hunters but survivalist such as the mugger Nadia and the cannibal Leland who survived as long as they did by programming themselves to be savages in their hostile environment where it is every man for himself. As Leland states "I'm a little too old & too tired for the honorable way of hunting game". They had be egoistic savages in order to prevail or as Leland put it "I wouldn't have survived this long if I had a heart", heart meaning capacity for sympathy which leads to altruistic behavior. An example is shown with Mahn, who remained altruistic and died because of it, evoking the "kill or be killed" theme. This reflects Gallo's view, that a civilized state conflicts with survival while a wild state is perfect, as our moralistic altruism are chains that holds us back from what is, dog eat dog (or life eats life as he puts it) because that hunter/prey dynamic has kept the population in wildlife in check and that is what the hunters present. In contrast to his view is solidarity, unity of sympathies among a group which Bower believes goes a long way when it comes to survival. This is reflected through Leland, who died as a result of his of selfishness and the fact that humanity survived due the sympathies Mahn and Nadia displayed. The film is addressing the positives and negatives of moralist altruism and egoism in regards to survival.
Gallo's paranoia caused him to see human civilization as a threat and the movie ends showing the population of Tanis being "1213" with an ellipsis appearing after it implying that numbers is going to grow and history is going to repeat itself. Christian Alvart did state that he wanted to rise questions about humanity with this film and this seems like partially a Malthusian commentary if you ask me. The ending echos the beginning showing the "technological evolution/ symbolic foreshadowing)" of space travel and showing the human population number evolving, growing. Throughout history, populations have grown slowly despite high birth rates due to the population-reducing effects of war, plagues and high infant mortality. During the 750 years before the Industrial Revolution, the world's population increased very slowly, under 250 million. The population reached a billion by the beginning of the 19th century. Technology is another aspect of civilization which as it grows so does living conditions, which leads to a growing population, Malthusian trap as its called. Malthusianism is the theory that population tends to increase faster than resources unless things such as moral restraint keeps the population growth in check or war reduces the population, called Malthusian catastrophe. Social Darwinism happens to be based on the Malthusian concept that humans require competition in order to survive in the future and the film seems to be a metaphor that ideology.