Interestingly, bowhead whale genome has a large percentage of transposable elements (TEs) (~32%), in particular long intercalated nuclear elements (LINE) such as LINE-1 (Keane et al., 2015). The same was observed in the genome of the humpback whale (Tollis et al., 2019). Active TEs are considered highly mutagenic and generally they become more active as organisms age, thus being associated with various age-associated pathologies such as cancer development and progression (Anwar et al., 2017; Bravo et al., 2020). However, a slow mutation rate has been identified in cetaceans, which can limit the generation of neoplastic cells and their progression (Tollis et al., 2019). It is possible that, like NMRs, whales possess mechanisms that make these retrotransposons less active (Yamaguchi et al., 2021). These may include some factors such as APOBECs, MOV10, RNASEL, SAMHD1, TREX1, ZAP, RISC, piRNAs, DNA repair enzymes, or epigenetic processes of DNA methylation and histone modification (Goodier, 2016), but it is necessary to corroborate it experimentally.