In this study, we directly quantify genomic changes within the last century in the two eastern gorillas: the critically endangered Grauer’s (Gorilla beringei graueri) and the endangered mountain gorillas (Gorilla beringei beringei) [] by sequencing whole genomes from historical specimens collected up to ca. Until the mid-1990s, the population was thought to number around 17,000 individuals. The total population of mountain gorillas is around 880 individuals, split into two separate groups. But the latest survey found that numbers had crashed to less than 4,000. The Eastern lowland gorilla population is now estimated to be fewer than 5,000. 2. The population of the eastern lowland gorilla has crashed in recent decades and is now under 4,000. Whilst the mountain gorilla resides in volcanic slopes of the Eastern Democratic Republic of the Congo, Grauer’s gorilla lives in the lush, lowland tropical rainforest of the country, and has a population of around 3,800 individuals. As their name suggests, the two species live in different habitats. Material and methods . Grauer’s Gorilla (G. b. graueri), one subspecies of Eastern Gorilla – has lost 77% of its population since 1994, declining from 16,900 individuals to just 3,800 in 2015. Priority species. As a great ape, gorillas are a WWF priority species. Population & distribution Population & distribution The eastern lowland gorilla occurs in the lowland and Albertine Rift montane forests of eastern Democratic Republic of the Congo (DRC). A QUICKLY DISAPPEARING SUBSPECIES. Elucidating past population dynamics in eastern gorilla populations will allow us to set our results within the broader context of climatological or anthropogenic factors that may have influenced the evolutionary history of eastern gorillas and other African mammals. The eastern lowland gorilla’s range has declined by at least a quarter over the last 50 years. 100 years ago and comparing them to present-day (modern) genomes [11, 12] (Figure 1A).