Discussions to date about communicating concepts of altruism to extraterrestrial intelligence (ETI) have focused on examples of altruism between members of the same species. However, because ETIs belong to species different from humans, analysis of yet another dimension of human altruism, the one which encompasses not only the non-human living world, but also non-living components of nature such as rivers, forests, mountains, and the like, is essential in light of the concepts and theories of evolutionary sociobiology. Because these beings have evolved independently, notions of kin selection would not guide their relations with humans. Similarly, given the vast distances of interstellar space and the long durations of round-trip exchanges of information, notions of reciprocity might also be irrelevant—at least at the level of biological individuals. We might, however, gain some clues to possible motivations for interstellar dialogues by considering altruism as revealed by human biophilia, or the affinity for other forms of life. Humans exhibit altruism towards others, including non-humans, because they assign some value to the receiver who may be a relative, a non-relative, a non-human plant or animal, or even a non-living river, mountain, or forest. Such value could be of two basic types, viz., extrinsic or instrumental value, which derives from the use value of a given subject, and intrinsic or inherent value, which exists regardless of utility. Altruism or cooperation appears to be a characteristic feature of mature and advanced societies, and is expected to be possessed by highly-advanced ETI societies. I argue in this chapter that the phenomenon of biophilia, which is perhaps a remnant of the nature-religions practiced by hunter-gatherer societies and is still practiced by indigenous ethnic groups all over the world, provides the basis for our ability to extend cooperation to ETI. If nature-religions are perceived as a meme-complex, the rites and rituals accompanying nature worship could form just one such meme in this meme-complex. The other memes in this complex may include an ability to appreciate nature’s beauty and bounty, recognition of an intrinsic value in nature, and a general feeling of biophilia. As we contemplate the possibility of communication with extraterrestrial intelligence, the meme-complex of biophilia may provide insights into a plausible prerequisite for interstellar discourse: altruism that extends far beyond the care of conspecifics.