On Jul. 9, 2020, a study, published in the journal Cell Systems, laid out a new framework for comparing dog-to-human aging. The researchers found the first eight weeks of a dog;s life is comparable to the first nine months of human infancy, but the ratio changes over time.

Researchers focused on one type of epigenetic change called methylation, a process in which molecules called methyl groups are attached to particular DNA sequences, usually parts of a gene. Attaching to these DNA regions effectively turns the gene into the “off” position. So far, researchers have identified that in humans, methylation patterns change predictably over time. These patterns have allowed the creation of mathematical models that can accurately gauge the age of an individual — called “epigenetic clocks.”