How do you determine how old an animal is? One way is to look at the teeth (tooth layer annulation and otolith layering). However, these methods are invasive and can generally only be used post-mortem, especially in wild animals as an age-at-death estimation. Two DNA based methods have been suggested as appropriate to determine age. Telomeres occur at the ends of chromosomal DNA and shorten as an animal ages. Aging is also correlated with changes in DNA methylation where a small molecule called a methyl group are added to the DNA. Louis-Stéphane IV Le Clercq a PhD student of Dr Desiré Lee Dalton (Lecturer in Forensic Science, Teesside University) has conducted a meta-analysis study that included 40 species and 60 age-estimation models. The study indicated that both methods can be used in studying age in animals and do not suffer significantly from variation due to differences in the lifespan of the species, genome size, karyotype, or tissue type but rather that quantitative method, patterns of inheritance, and environmental factors should be the main considerations. However, methylation may be superior to telomere length in terms of accuracy and cross-taxa portability; however, costs may be higher depending on the technique use to study methylation.

An animal cell indicating the mechanisms of cellular ageing at the molecular level that are currently used as molecular biomarkers for age.

Access the publication through the publisher’s website with this link (DOI: http://doi.org/10.1111/brv.12992)