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Hominin evolution was caused by introgression from Gorilla

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My article 'Hominin evolution was caused by introgression from Gorilla' was one of the top 5 most viewed #Anthropology articles published in @thePeerJ journal in 2018!
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77 downloads within 2 days for preprint of Hominin evolution caused by introgression from Gorilla https://t.co/bkTLDOFLaj @aylwyn_scally The first iteration looked at Pliocene hominin, the second on Pan-Homo split (more mainstream), the third integrated both, "hominin evolution" https://t.co/SBMdwiUKfy
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peerJ: Hominin evolution was caused by introgression from Gorilla https://t.co/l1nqE6GhrO
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Supplemental Information

Figure 1: Phylogenetic tree showing how Gorilla introgression caused the human-chimpanzee split

Phylogenetic tree showing how introgression caused the speciation of humans. This introgression speciation model predicts an early split for Paranthropus and Australopithecus, increasingly shown in the fossil record (Haile-Selassie, 2015, 2016; Wood, 2016), and also shows that the evolution of genes that ended up in Australopithecus, and therefore in extant humans, as well as in Paranthropus, can and should be traced along the gorilla lineage as well

DOI: 10.7287/peerj.preprints.27163v1/supp-1

Figure 2. Morphological traits in Gorilla and the hybrid lineages Paranthropus and Australopithecus

Introgression from Gorilla caused the speciation of both Australopithecus and Paranthropus, and means that traits that have evolved independently in the gorilla lineage were transferred into the hybrid lineages. Paranthropus are often described as “gorilla-like”, they have sagittal crests which suggest strong muscles of mastication, and broad, grinding herbivorous teeth, that led to the name “nutcracker man” for Paranthropus boisei who lived between 2.4–1.4 Ma.

DOI: 10.7287/peerj.preprints.27163v1/supp-2

Figure 2. Morphological traits in Gorilla and the hybrid lineages Paranthropus and Australopithecus

Introgression from Gorilla caused the speciation of both Australopithecus and Paranthropus, and means that traits that have evolved independently in the gorilla lineage were transferred into the hybrid lineages. Paranthropus are often described as “gorilla-like”, they have sagittal crests which suggest strong muscles of mastication, and broad, grinding herbivorous teeth, that led to the name “nutcracker man” for Paranthropus boisei who lived between 2.4–1.4 Ma.

DOI: 10.7287/peerj.preprints.27163v1/supp-3

Figure 2. Morphological traits in Gorilla and the hybrid lineages Paranthropus and Australopithecus

Introgression from Gorilla caused the speciation of both Australopithecus and Paranthropus, and means that traits that have evolved independently in the gorilla lineage were transferred into the hybrid lineages. Paranthropus are often described as “gorilla-like”, they have sagittal crests which suggest strong muscles of mastication, and broad, grinding herbivorous teeth, that led to the name “nutcracker man” for Paranthropus boisei who lived between 2.4–1.4 Ma.

DOI: 10.7287/peerj.preprints.27163v1/supp-4

Fig. 3. Phylogenetic tree with hominine mtDNA and ps5 homologs

Joint phylogenetic tree of hominine mtDNA and the ps5 pseudogene of mtDNA. Black and pink lines depict the mitochondrial and the pseudogene lineages respectively, diverging from their mitochondrial common ancestor. The insertion of mtDNA fragments into the nuclear genome of Gorilla can be roughly estimated to 1.8 Myr after the Gorilla/Pan-Homo split, and the transfer to Pan and Homo to the human-chimpanzee split, along with 30% of the Gorilla genome.

DOI: 10.7287/peerj.preprints.27163v1/supp-5

Fig. 4. Fossil record for a taxonomic classification of Paranthropus ​deyiremeda

The Burtele foot, BRT-VP-2/73, found in 2009 (Haile-Selassie, 2015) in Burtele at Woranso-Mille, Afar, tentatively assigned Au. deyiremeda (Haile-Selassie, 2015), contemporaneous with Au. afarensis, shows distinct locomotor adaptation as it retains a grasping hallux, in contrast to the human-like adducted hallux that had developed in Australopithecus afarensis. The conclusive evidence that hominin evolution was caused by introgression from Gorilla suggests that Au. deyiremeda is better classified as Paranthropus deyiremeda. With a revised taxonomic classification, building on a combination of genomic data and fossil records, it can be predicted that Paranthropus and Australopithecus, like Pan and Homo, diverged through lineage sorting as the two lineages co-opted genes from the Gorilla lineage to adapt for separate niches.

DOI: 10.7287/peerj.preprints.27163v1/supp-6

Fig. 5. Gorilla-like traits in the Paranthropus lineage a result of lineage sorting from Gorilla

Paranthropus aethiopicus, 2.8-2.3 Ma, with gorilla-like sagittal cranial crests as an attachment for strong muscles of mastication, a dietary adaptation. The genetic proof of an introgression event at the time of the Pan-Homo spit shows that the most parsimonious origin for those features within Paranthropus was lineage sorting from the introgression event, originating in Gorilla, rather than convergent evolution. Image from the public domain (CC BY-SA 3.0).

DOI: 10.7287/peerj.preprints.27163v1/supp-7

Additional Information

Competing Interests

The authors declare that they have no competing interests.

Author Contributions

Johan Nygren conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.

Data Deposition

The following information was supplied regarding data availability:

The manuscript references data from genome sequencing as well as the fossil record.

Funding

The authors received no funding for this work.


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