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Home , Chororapithecus, Nakalipithecus

COMMENTARY

New fill the gap

Raymond L. Bernor* Laboratory of Evolutionary Biology, Department of Anatomy, College of Medicine, Howard University, 520 W Street, NW, Washington, DC 20059; and Sedimentary Geology and Paleobiology Program, Geosciences/Earth Sciences, National Science Foundation, 4201 Wilson Boulevard, Arlington, VA 22230

he relative abundance of Eur- a time of sweeping paleoclimatic, faunal, or hominins from an area about 0.1% of asian apes between 12.5 and 8 and floral evolution in Western Eurasia the African continent as a whole.’’ Cote Ma—in contrast to a dearth of and Africa: a change from tropical and (21) has demonstrated that the abun- African apes during the same subtropical forested conditions to more dance of fossil remains in Eur- Tchronologic interval—has led some in- open-country, seasonal conditions. In asia,—compared with a dearth of vestigators (1, 2) to suggest that the Af- Eurasia, this change is recorded as the similar-aged apes in Africa—is due to rican ape–human clade evolved from a so-called Pikermian biome (18), when sampling: Eurasian localities are much Eurasian ancestor, specifically, a previ- large faunas with the diverse richer and more diverse during this in- ously undescribed and unnamed ape lineages of horses, antelopes, giraffes, terval than African localities, and hence from Turkey (3). In the last several rhinoceroses, and distant relatives of their apes are better represented. Africa weeks, three new ape genera have been elephants evolved and extended their has yielded the oldest and most diverse reported, one from Turkey (Ouran- geographic ranges from Spain to China – hominoids. It is the opithecus turkae), one from Ethiopia between 8 and 5 Ma. The origins of this only continent where the chimp and ( abyssinicus), and the community are not well understood, but live in the wild, and it has the latest, nakayamai, from the Sinap fauna in Turkey records their earliest bona fide hominid sensu stricto Kenya, which is the subject of the article remains. Moreover, there is no evidence by Kunimatsu et al. (4) in a recent issue of a mass ape extinction at the end of of PNAS. Molecular studies the Middle Miocene, nor is it likely that a Eurasian species founded the African Filling the Gap continue to provide ape–human clade as the result of a bio- N. nakayamai is described as a large geographic retreat from Eurasia (1). ape, the size of a female gorilla, dating robust hypotheses What the science of biogeography re- 9.9–9.8 Ma. Its dentognathic morphol- lentlessly teaches us is that species ex- ogy includes thick-enameled molars, a of ape–human tend their ranges when geographic and thickened mandibular body, and a low- paleoenvironmental circumstances allow crowned upper canine that is as broad divergence dates. it: nothing more, nothing less. as it is long. In these features, N. na- Japanese paleoanthropology is a rela- kayamai most closely resembles the tively small field, with few researchers slightly younger 9.6- to 8.7-Ma Greek earliest occurrence Ϸ10.6–9.7 Ma (19). compared with North American, Euro- ape Ouranopithecus macedoniensis (5–7). The Late Miocene of Africa records a pean, and African research schools. So it The Turkish ape, O. turkae,isthe cohort of these Pikermian taxa as immi- is remarkable that the two Japanese hu- youngest, with a biochronological place- grants into northern and eastern Africa man-origins research teams—one working ment of 8.7–7.4 Ma (8). The dental Ϸ8 Ma, including species of mustelids, with Ethiopian counterparts at Chorora, morphology of Nakalipithecus and of the hyaenids, felids, horses, giraffes, and Ethiopia, and the other working in the two Ouranopithecus species suggests antelopes (17). Few large ex- Samburu Hills and Nakali, Kenya—have hard-object frugivory and, together with ited Africa at this time, but Nakalipithe- made three of the most exciting and im- their large sizes, implies terrestrial for- cus, being older and more primitive than portant East African ape discoveries in aging for at least a portion of their its reported descendent Ouranopithecus, the last few years. All three of these sites niche-space. is a plausible candidate for this distinc- were previously investigated by multiple The apparent 14- to 7-Ma African tion. It is not surprising that Kunimatsu research teams that found no ape fossils ‘‘ape gap’’ (9) is now populated not only et al. (4) report here that the associated at these localities. It is imperative to ac- by Nakalipithecus but also by the pene- paleoenvironments of Nakalipithecus knowledge that these recent discoveries contemporaneous Kenyan large ape and are similar to the occurred only because of the expertise, Samburupithecus kiptalami (10), dated seasonal, sclerophyllous evergeen wood- tenacity, and hard work of these scientists. slightly younger at 9.6 Ma (11, 12), and lands of the Pikermian biome (20). Our hats are off to them. by yet another large gorilla-like ape, C. Darwin taught us that imperfections of abyssinicus, from the 10.5- to 10-Ma Origin of the African Ape–Human Clade the geological record should not be over- horizons of Chorora, Ethiopia (13). Ad- Why the radical shift in scientific opin- interpreted as biological signal. These new ditional isolated, but important, large ion from the out-of-Europe view to a discoveries show that gaps are best filled ape remains from Ngorora, Kenya, lo- plausible African origin of the African the old-fashioned way. But beyond the calities believed to be Ϸ12.5 Ma (14) ape–human clade? In a poignant short gap-filling foreseen by Darwin, paleobiolo- may evidence even greater species diver- essay on the subject, Hill (9) has re- gists are now blessed with extensive new sity. Did the African ape–human clade ported a simple, yet important, set of arise in Africa, after all? Some think so facts: ‘‘Africa is approximately (9, 15–17). Where there was once a 4,554,123.6 square kilometers in area, Author contributions: R.L.B. wrote the paper. wide gap, we are now provided with a but nearly all of the relevant sites could The author declares no conflict of interest. substantial intra-African great ape diver- be grouped in a box a few hundred See companion article on page 19220 in issue 49 of volume sity in the 12.5- to 9.6-Ma interval. miles on each side. So when people talk 104. Nakalipithecus, Samburupithecus, and about fossil apes or hominins in ‘Africa’ *E-mail: [email protected]. Chororapithecus lived in Africa’s rifts at they are really talking about fossil apes © 2007 by The National Academy of Sciences of the USA

www.pnas.org͞cgi͞doi͞10.1073͞pnas.0710109105 PNAS ͉ December 11, 2007 ͉ vol. 104 ͉ no. 50 ͉ 19661–19662 Downloaded by guest on September 30, 2021 toolkits with which to unlock ancient evo- between environmental change and biotic and under what circumstances the African lutionary histories. We can now achieve community response. Molecular studies ape–human clade evolved. Expanded pa- chronological positioning of continental continue to provide robust hypotheses of leontological exploration, founded in fossil localities beyond our wildest dreams ape–human divergence dates. However, it sound collection, conservation, documen- of 40 years ago. The possibility of corre- is new fossil discoveries, such as that de- tation, analysis, and reporting of whole lating paleoenvironmental signals re- scribed by Kunimatsu et al. (4), that biotic communities, coupled with the de- corded in deep ocean cores with those in promise to provide us with the most es- velopment of secure geologic contexts, are terrestrial lake systems allows exciting new sential data about human origins and give all essential elements of the continued testable hypotheses about the relationships us new insights into when, where, how, quest to discover our origins.

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19662 ͉ www.pnas.org͞cgi͞doi͞10.1073͞pnas.0710109105 Bernor Downloaded by guest on September 30, 2021