I often wonder why are chimpanzees and bonobos so similar to each other, at least on their external appearance, and seem to have evolved very slowly over the past two to three million years. Modern Humans, on the other hand, compared to our 3 million year old ancestors the Australopiths and Homo habilis are very different in our abilities and appearance.
Bonobos (Pan paniscus) are a species of ape that lives in the tropical rainforests of Western Africa in the Democratic Republic of the Congo (DRC). They are, together with the chimpanzees, the closest living relatives of human beings. The chimps, (Pan troglodytes) have a wider range in both territory and environment, from tropical jungles to savannas. They live in a wide swath across central Africa, from Guinea and Liberia on the Atlantic area of West Africa, through Mali, Sierra Leone, and across th heart of Africa (Habon, Congo, DRC, Cameroon, Ruanda, and Uganda) and into East Africa (Tanzania).
Chimpanzees and bonobos share a comon ancestor. They diverged into two distinct species between 2.5 and 1.5 million years ago. But, they don't seem to be all that different (on the outside).
It seems that, unlike humans, and our ancestors, they didn't admix with each other. The Congo River seems to have been a physical barrier that kept chimps and bonobos apart (Diogo, 2017).
According to Diogo, although bonobos and chimpanzees are different, the differences between them accumulated at a much lower rate than the differences that either species have with modern humans.
We grew apart, with us mutating faster than either of the Pan species: The rate vs. humans is over 2.5 times higher for the common chimpanzee and over 1.6 times higher for the bonobo, vs. their divergences between each other.
Remarkable difference, considering that we are said to share 98.7% of their genome with us (More on this "myth" further down).
Behavior-wise, bonobos and chimps are different. See Prüfer, 2012 and Wilson, 2021. Bonobos are more intensly sexual (and creative in that field too!), female dominated and less aggressive towards other bands; they retain the playful attitude of infancy even as they age. Chimpanzees are the opposite (aggressive males, hierarchical, competitive).
However, alpha bonobo males have more offspring than lower ranking ones, and even more than chimpanzee alphas, showing that even in matriarchal societies, there can be a polygynic bias.
Chimps use tools: stones to crack nuts, and wood spears to hunt monkeys or dig for roots. Bonobos don't. Chimps can kill their kin, bonobos don't
Based on these behaviors, it seems that modern humans share traits from both ape species.
Human-Chimp & Bonobo split date
I have always believed that the 6 million year (My) date assigned to the split between humans and Pan, is too recent (see this post). A recent study by Oliveira Coelho et al., 2026 (Parting ways: Pan-Homo divergence revisited) acknowledges that over the past decades, the date has been gradually pushed back "from ~ 6 Ma to ~ 8.5 Ma over the past 56 years" This is important because it impacts on the molecular clock, often gauged using this split date (take the genetic difference between Pan and us, and divide it by the time elapsed since we split, and you have the mutation rate. A more distant split implies a lower mutation rate).
However, fossils are not there! There is a gap in the fossil record spanning the period ~7 to 9 My ago.
Let's see what future research finds.
Similarity between Humans and Pan
A study by Yoo et al., 2024 (Complete sequencing of ape genomes) is quite clear that we are not 99% similar to them (highlight is mine): "The oft-quoted statistic of ~99% sequence identity between chimpanzee and human holds for most of the genome when considering single-nucleotide variants (SNVs) (Fig. 2b). However, comparisons of T2T genomes suggest a much more nuanced estimate. Examining the distribution of 1 Mbp aligned windows shows that the tail of that distribution is much longer with 12.5–27.3% of the genome failing to align or inconsistent with a simple 1-to-1 alignment, especially within centromeres, telomeres, acrocentric regions, and SDs." Structure and content don't seem to line up in the comparison leaving only a 87.5 to 72.7% similarity.
This is quite a spread, from 99% down to 72.7% is a big difference.
Interestingly, regarding the X to A ratio (mentioned in my previous post), Yoo et al., reported an extremely low value: "for the human–chimpanzee–bonobo ancestor (Ne=76,700, X-to-A ratio of 0.42)."
Are we descended from a common ancestor of chimps and bonobos? Or not at all?
We should bear in mind that when we compare humans with the Pan, we are looking at contemporary species, alive now. But we may be far more different from the last common ancestor (LCA) of both humans and chimpanzees-bonobos (Wilson). This LCA could be radically different from Pan and Homo.
The LCA also had a more Pan-like appearance than human. Sekhavati et al., 2025 analyzed the shape of human, hominin, and Pan feet, and found that it "supports the hypothesis of a Pan-like last common ancestor of humans and chimpanzees." Furthermore, the first purported ancestors of our human lineage "the Paranthropus and the Australopithecus africanus + Australopithecus sediba clades evolved arboreal characteristics, suggesting adaptations for arboreality." This is relevant as they are probably not our ancestors after all (more below).
In fact, the earliest human ancestors after the split, members of the Homo group, are probably misclassified as such; I am refering to the Homo habilis. Fortin, 2025 argues that they were added to the Homo group because Leakey argued that even though they had minute brains (only 600 cm3) they walked on two feet and made stone tools. Now, some scholars are having second thoughts. Habilis seems to be more similar to Australopiths than to Homo (see my post: Was Homo habilis a member of our Homo genus?) Even Homo rudolfensis should probably be removed from the Homo group.
In this regard Vaneechoutte et al., 2024 (see my post about his paper: Australopithecines are not our ancestors at all (says study)) wrote: "Instead of considering [Australopith] graciles as ancestral to Pan and robusts as ancestral to Gorilla, as suggested by Kleindienst et al., Verhaegen considered the eastern African australopithecines, such as A. afarensis (incl. Lucy) as well as P. boisei to be ancestral or closer to the genus Gorilla, and the South-African australopithecines, A. africanus (incl. the Taung child) and P. robustus, ancestral or closer to the genus Pan." Vaneechoutee argues that an Ardipithecus-like ancestor evolved into Australopiths, and these evolved into A. africanus and Paranthropus robustus, leading to Pan, and the A. afarensis and P. boisei leading to Gorilla. Humans did not split from Pan, instead they did so from the Adripithecus via an "unknown missing link" adding that "Australopithecines Are Possibly Not Hominins Because Our Ancestors May Not Have Been Present in Africa in between 4 and 3 Ma."
It is possible that Eurasian apes evolved into our ancestor, Homo erectus in Western Eurasia, and that these are the base of the homo lineage.
Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall ©
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