Alternative Animal Models of Aging Research

Most research on mechanisms of aging is being conducted in a very limited number of classical model species, i.e., laboratory mouse (<i>Mus musculus</i>), rat (<i>Rattus norvegicus domestica</i>), the common fruit fly (<i>Drosophila melanogaster</i>) and roundworm (<i>Caenorhabditis elegans</i>). The obvious advantages of using these models are access to resources such as strains with known genetic properties, high-quality genomic and transcriptomic sequencing data, versatile experimental manipulation capabilities including well-established genome editing tools, as well as extensive experience in husbandry. However, this approach may introduce interpretation biases due to the specific characteristics of the investigated species, which may lead to inappropriate, or even false, generalization. For example, it is still unclear to what extent knowledge of aging mechanisms gained in short-lived model organisms is transferable to long-lived species such as humans. In addition, other specific adaptations favoring a long and healthy life from the immense evolutionary toolbox may be entirely missed. In this review, we summarize the specific characteristics of emerging animal models that have attracted the attention of gerontologists, we provide an overview of the available data and resources related to these models, and we summarize important insights gained from them in recent years. The models presented include short-lived ones such as killifish (<i>Nothobranchius furzeri</i>), long-lived ones such as primates (<i>Callithrix jacchus, Cebus imitator, Macaca mulatta</i>), bathyergid mole-rats (<i>Heterocephalus glaber, Fukomys spp.</i>), bats (<i>Myotis spp.</i>), birds, olms (<i>Proteus anguinus</i>), turtles, greenland sharks, bivalves <i>(Arctica islandica</i>), and potentially non-aging ones such as <i>Hydra</i> and <i>Planaria</i>.