Event 30

10 million years ago

This is an image of three Chororapithecus abyssinicus teeth (left) next to a modern gorilla mandible (right). Chororapithecus is the earliest probable species of gorilla. It indicates that the last common ancestor of the human/ chimp lineage and gorillas may have lived more than 10-11mya (at least 2my earlier than previously thought).
Credit: Photo by Gen Suwa, University of Tokyo. This photo is used with permission. All rights reserved.

Genetic evidence suggests that the last common ancestor of the African apes (chimpanzees, bonobos or pygmy chimpanzees, and gorillas) and humans was around seven million years ago. African ape fossils are not very common, probably because they tend to live in humid, tropical forests with acid soils that do not preserve bones very well. Many anthropologists suspected that earlier African apes might look more similar in size and shape to modern chimpanzees or bonobos than to the much larger gorillas.

Recently two sites in Ethiopia dating to 10 million years age have yielded fragmentary remains of apes that, to the surprise of many scientists, appear to resemble modern gorillas more than other known species. Whether this will ultimately change our views regarding the tempo and mode of ape and human evolution (discussed below) is still not clear.

This is a western lowland male silverback gorilla. Its scientific name is Gorilla gorilla. Gorillas are the closest living relatives of humans after the chimpanzees. Gorillas and humans share about a 95-99% similarity in DNA composition.
Credit: Photo by Mila Zinkova, Wikipedia.


These fossils come from well-dated deposits in East Africa, and can be directly compared with modern ape morphology. The size and shape of these fossils most closely resemble modern gorillas rather than chimpanzees, bonobos, or humans.


Genetic evidence suggests that the last common ancestor of humans and the African apes (chimpanzees, bonobos, and gorillas) was in the last seven million years or so. Finding gorilla-like forms at 10 million years may indicate our early ape ancestors were more gorilla-like, it may indicate that gorillas branched off earlier than was previously expected, or it may indicate that these forms represent a side–branch of ape evolution with some convergent (independent) gorilla-like features that were not ancestral to us. In any case, these fossils are extremely interesting and further discoveries in this time period will clearly shed more light on ape and human evolution.


Suwa, G., et al. A new species of great ape from the late Miocene epoch in Ethiopia. Nature 448, 921-924 (23 August 2007)

This website is gives information about the geography of gorillas.

This is a kid-friendly site about gorillas, with a short paragraph about the evolution of gorillas.

This is a ScienceFriday webpage with a streaming audio clip about “Tickling Gorillas and the Evolution of Laughter.”

This website about gorillas briefly mentions the evidence about their evolution, and emphasises conservation.

Continue to overview of Time Scale 4

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