Data from: Epigenetic estimation of age in humpback whales

Animal age is a fundamental aspect of animal ecology, but is difficult to determine in many species. Humpback whales exemplify this as they have a lifespan comparable to humans, mature sexually as early as four years and have no reliable visual age indicators after their first year. Current methods for estimating humpback age cannot be applied to all individuals and populations. Assays for human age have recently been developed recently based on age-induced changes in DNA methylation of specific genes. We used information on age-associated DNA methylation in human and mouse genes to identify homologous gene regions in humpbacks. Known-age humpback skin samples from a unique, intensively-studied population with individuals tracked since birth were employed to calibrate relationships between cytosine methylation and age. Seven of 37 cytosines assayed for methylation level in humpback skin had significant age-related profiles. The three most age-informative cytosine markers were selected for a humpback epigenetic age assay which predicts age from skin samples with a standard deviation of 3.0 years. A population age profile was generated with epigenetic skin biopsy analysis for eastern Australian humpbacks sampled in 2009 and compared to age profiles for the same population generated with lethal methods from 1952-1962. The utility of the epigenetic method for ordinal age determination was also tested. This is the first epigenetic age estimation method for a wild animal species and the approach we took for developing it can be applied to many other vertebrates.