The data on the neoteny (prolongation of youth and retardation of aging) in naked mole rat (Heterocephalus glaber) and Homo sapiens are summarized. Fifty-eight neotenic traits have been described by now in the naked mole rat at the organismal, tissue, cellular, and metabolism levels. Among them, there are traits that increase the lifespan, including mild depolarization of mitochondria that prevents generation by these organelles of reactive oxygen species known to strongly promote aging. Mild mitochondrial depolarization disappears with age in short-lived mammals (mouse Mus musculus) much faster than in long-lived mammals (e.g., naked mole rats and bats). The development of neoteny in naked mole rats has been due to the social organization. These animals live in subterranean colonies, where sexual reproduction is monopolized by the queen and one or several males who are defended and provided with nutrition by numerous subordinates. Humans have achieved a gradual increase in the lifespan first due to neoteny, and then to the technical progress, which can be observed by comparing the lifespan curves of chimpanzees, hunter-gatherers of the Paraguayan Ache tribe, and residents of Sweden from the XVII century to the present day. Significantly different rates of neoteny and technical progress make it possible to discriminate between the contributions of these two longevity mechanisms.