A new Late Miocene great ape from Kenya and its implications for the origins of African great apes and humans

Kunimatsu, Yutaka; Nakatsukasa, Masato; Sawada, Yoshihiro; Sakai, Tetsuya; Hyodo, Masayuki; Hyodo, Hironobu; Itaya, Tetsumaru; Nakaya, Hideo; Saegusa, Haruo; Mazurier, Arnaud; Saneyoshi, Mototaka; Tsujikawa, Hiroshi; Yamamoto, Akane; Mbua, Emma

doi:10.1073/pnas.0706190104

Cited by 170 publications

(109 citation statements)

References 37 publications

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“…In primates, the VENs are present in FI only in great apes and humans (see Table 1). This is the same taxonomic distribution as was found for the VENs in LA (Nimchinsky et al 1999), which suggests that the VENs emerged as a specialized neuron type in the common ancestor of great apes and humans, a primitive ape living in the Miocene period (Kunimatsu et al 2007). However, in orangutans we found only one out of seven individuals examined to have a substantial VEN population in FI and LA.…”

Section: Resultssupporting

confidence: 49%

The von Economo neurons in frontoinsular and anterior cingulate cortex in great apes and humans

et al. 2010

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The von Economo neurons (VENs) are large bipolar neurons located in frontoinsular (FI) and anterior cingulate cortex in great apes and humans, but not other primates. We performed stereological counts of the VENs in FI and LA (limbic anterior, a component of anterior cingulate cortex) in great apes and in humans. The VENs are more numerous in humans than in apes, although one gorilla approached the lower end of the human range. We also examined the ontological development of the VENs in FI and LA in humans. The VENs first appear in small numbers in the 36th week post-conception, are rare at birth, and increase in number during the first 8 months after birth. There are significantly more VENs in the right hemisphere than in the left in FI and LA in postnatal brains of apes and humans. This asymmetry in VEN numbers may be related to asymmetries in the autonomic nervous system. The activity of the inferior anterior insula, which contains FI, is related to physiological changes in the body, decisionmaking, error recognition, and awareness. The VENs appear to be projection neurons, although their targets are unknown. We made a preliminary study of the connections of FI cortex based on diffusion tensor imaging in the brain of a gorilla. The VEN-containing regions connect to the frontal pole as well as to other parts of frontal and insular cortex, the septum, and the amygdala. It is likely that the VENs in FI are projecting to some or all of these structures and relaying information related to autonomic control, decision-making, or awareness. The VENs selectively express the bombesin peptides neuromedin B (NMB) and gastrin releasing peptide (GRP) which are also expressed in another population of closely related neurons, the fork cells. NMB and GRP signal satiety. The genes for NMB and GRP are expressed selectively in small populations of neurons in the insular cortex in mice. These populations may be related to the VEN and fork cells and may be involved in the regulation of appetite. The loss of these cells may be related to the loss of satiety signaling in patients with frontotemporal dementia who have damage to FI. The VENs and fork cells may be morphological specializations of an ancient population of neurons involved in the control of appetite present in the insular cortex in all mammals. We found that the protein encoded by the gene DISC1 (disrupted in schizophrenia) is preferentially expressed by the VENs. DISC1 has undergone rapid evolutionary change in the line leading to humans, and since it suppresses dendritic branching it may be involved in the distinctive VEN morphology.

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Section: Resultssupporting

confidence: 49%

The von Economo neurons in frontoinsular and anterior cingulate cortex in great apes and humans

et al. 2010

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“…1). Available data suggest differences in physiographic settings (e.g., paleoelevation and location in the Rift Valley) between the three sites that would have affected paleoclimatic variables such as temperature, precipitation, aridity, and seasonality (18,20,30,31). None of the sites overlap in age; hence, it is not possible to discern the influence of local (i.e., sitespecific) versus regional climate on vegetative structure at each site.…”

Section: Resultsmentioning

confidence: 99%

“…Additional details of the sampling and analytical methods are provided in SI Appendix. Taxonomic identification of mammalian fauna from the Nakali, Namurungule, Nawata, and (Lothagam) Nachukui formations is presented in SI Appendix, Table S2, and reviewed in SI Appendix (18,30,(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51). We analyzed fossil enamel from large herbivores listed in SI Appendix, Table S1.…”

Section: Methodsmentioning

confidence: 99%

“…All sites in this study have yielded important hominid material. Nakali and the Samburu Hills, located in the Suguta Valley, Kenya, have yielded the Late Miocene hominids Nakalipithecus nakayami (18) and Samburupithecus kiptalami (19), respectively, which likely represent stem hominines (23). With Chororapithecus abyssinicus, these are the only known East African hominids between 11 and 9 Ma (24).…”

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confidence: 99%

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Late Miocene to Pliocene carbon isotope record of differential diet change among East African herbivores

Uno

Cerling

Harris³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Stable isotope and molecular data suggest that C 4 grasses first appeared globally in the Oligocene. In East Africa, stable isotope data from pedogenic carbonate and fossil tooth enamel suggest a first appearance between 15-10 Ma and subsequent expansion during the Plio-Pleistocene. The fossil enamel record has the potential to provide detailed information about the rates of dietary adaptation to this new resource among different herbivore lineages. We present carbon isotope data from 452 fossil teeth that record differential rates of diet change from C 3 to mixed C 3 /C 4 or C 4 diets among East African herbivore families at seven different time periods during the Late Miocene to the Pliocene (9.9-3.2 Ma). Significant amounts of C 4 grasses were present in equid diets beginning at 9.9 Ma and in rhinocerotid diets by 9.6 Ma, although there is no isotopic evidence for expansive C 4 grasslands in this part of the Late Miocene. Bovids and hippopotamids followed suit with individuals that had C 4 -dominated (>65%) diets by 7.4 Ma. Suids adopted C 4 -dominated diets between 6.5 and 4.2 Ma. Gomphotheriids and elephantids had mostly C 3 -dominated diets through 9.3 Ma, but became dedicated C 4 grazers by 6.5 Ma. Deinotheriids and giraffids maintained a predominantly C 3 diet throughout the record. The sequence of differential diet change among herbivore lineages provides ecological insight into a key period of hominid evolution and valuable information for future studies that focus on morphological changes associated with diet change.carbon isotopes | herbivore diet | bioapatite | paleodiet | mammal

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“…Taxonomic diversification and coexistence of multiple largebodied Miocene hominoids are well documented in the Cenozoic fossil record (77). There is adequate fossil evidence to show that multiple hominin taxa coexisted during the Pleistocene.…”

Section: Pliocene Hominin Diversity Sympatry and The Question Of Nimentioning

confidence: 95%

The Pliocene hominin diversity conundrum: Do more fossils mean less clarity?

Haile‐Selassie

Melillo

2016

Proc. Natl. Acad. Sci. U.S.A.

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Recent discoveries of multiple middle Pliocene hominins have raised the possibility that early hominins were as speciose as later hominins. However, debates continue to arise around the validity of most of these new taxa, largely based on poor preservation of holotype specimens, small sample size, or the lack of evidence for ecological diversity. A closer look at the currently available fossil evidence from Ethiopia, Kenya, and Chad indicate that Australopithecus afarensis was not the only hominin species during the middle Pliocene, and that there were other species clearly distinguishable from it by their locomotor adaptation and diet. Although there is no doubt that the presence of multiple species during the middle Pliocene opens new windows into our evolutionary past, it also complicates our understanding of early hominin taxonomy and phylogenetic relationships.If one looks back over the controversies of human evolution, they have one element in common: new discoveries, theories, methods came along which no one in the controversy anticipated. The "facts" changed, and consequently people were not right or wrong in any simple way.S. L. Washburn and R. L. Ciochon, 1974 (1) New fossil discoveries and analytical methods that have proliferated during the last few decades have fundamentally changed how we study and interpret hominin fossils and understand human evolution. The discovery and subsequent naming of Australopithecus afarensis in the late 1970s was one of the major milestones in paleoanthropology (2). Its discovery not only pushed the record of hominins to earlier than 3 million years ago (Ma) (2), but also demonstrated the antiquity of human-like bipedality (3). However, the taxonomic homogeneity of the Au. afarensis hypodigm has been questioned since its naming (4-7), even though the Hadar fossil sample appears to be no more variable than other living ape species (8-11). A consensus emerged during the 1980s in which Au. afarensis, dated to between 3.7 and 2.9 Ma, was considered to be the sole early hominin species older than 3 Ma, largely supported by the lack of fossil evidence to indicate otherwise.When Australopithecus bahrelghazali was named in 1995 based on an approximately 3.5-Ma partial mandible from Chad (12), it was quickly dismissed as a geographic variant of Au. afarensis (13-15). The initial descriptions of Ardipithecus ramidus (16) and Australopithecus anamensis (17), followed by the naming of even earlier hominin species, such as Orrorin tugenensis (18), Ardipithecus kadabba (19,20), and Sahelanthropus tchadensis (21), extended the antiquity of our lineage as far back as >6 Ma. These early hominins initially appeared to show no temporal or spatial overlap, and hence reinforced the idea that the early phases of hominin evolution were characterized by phenetic continuity and phyletic gradualism, with only one hominin species existing in a region at any given time >3 Ma (e.g., ref. 22; see discussions below).The discovery of the Burtele partial foot from Ethiopia (23), the naming of Kenyan...

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A new Late Miocene great ape from Kenya and its implications for the origins of African great apes and humans

Cited by 170 publications

References 37 publications

The von Economo neurons in frontoinsular and anterior cingulate cortex in great apes and humans

The von Economo neurons in frontoinsular and anterior cingulate cortex in great apes and humans

Late Miocene to Pliocene carbon isotope record of differential diet change among East African herbivores

The Pliocene hominin diversity conundrum: Do more fossils mean less clarity?

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