| Macroevolutionary effects on primate trophic evolution and their implications for reconstructing primate origins Publication date: August 2019 Source: Journal of Human Evolution, Volume 133 Author(s): Jeremiah E. Scott AbstractThe visual-predation hypothesis proposes that certain derived features shared by crown primates reflect an insectivorous ancestry. Critics of this idea have argued that because insectivory is uncommon among extant primates it is unlikely to have been a major influence on early primate evolution. According to this perspective, the low frequency of insectivory indicates that it is an apomorphic deviation from the mostly conserved primate ecological pattern of herbivory. The present study tests two alternative hypotheses that are compatible with an insectivorous ancestor: (1) that trophic evolution was biased, such that herbivory evolved repeatedly with few shifts back to insectivory, and (2) that insectivorous lineages have diversified at a lower rate than herbivorous lineages owing to differential trophic effects on speciation and extinction probabilities. Model-based analysis conducted using trait data for 307 extant primate species indicates that rates of transition into and out of insectivory are similar, rejecting the hypothesis of biased trophic evolution. On the other hand, the hypothesis of asymmetric diversification is supported, with insectivorous lineages having a lower rate of diversification than herbivorous lineages. This correlation is mediated by activity pattern: insectivory occurs mostly in nocturnal lineages, which have a lower diversification rate than diurnal lineages. The frequency of insectivory also appears to have been shaped by repeated transitions into ecological contexts in which insectivory is absent (large body size) or rare (diurnality). These findings suggest that the current distribution of trophic strategies among extant primates is the result of macroevolutionary processes that have favored the proliferation and persistence of herbivory relative to insectivory. This conclusion implies that the low frequency of insectivory is not necessarily evidence against the visual-predation hypothesis. |
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Publication date: July 2019
Source: Journal of Human Evolution, Volume 132
Author(s): Laura MacLatchy, James Rossie, Alexandra Houssaye, Anthony J. Olejniczak, Tanya M. Smith
Abstract
The early Miocene site of Moroto II, Uganda has yielded some of the oldest known hominoid fossils. A new partial mandible (UMP MORII 03'551) is notable for its long tooth row and large, narrow M2 with well-developed cristids - a morphological combination previously unknown for large bodied catarrhines of the Early Miocene and suggesting folivory. The tooth proportions are compatible with belonging to the same taxon as the maxilla UMP 62-11, the holotype of Morotopithecus bishopi; likewise, the long tooth row and vertical planum of UMP MORII 03'551 suggest that it may represent the same taxon as mandible(s) UMP 66-01 and UMP 62-10. Canine size strongly suggests UMP MORII 03'551 is a female. Comparisons of the tooth crown morphology and tooth row proportions, relative enamel thickness, enamel-dentine junction morphology, long-period line periodicity, and dental wear patterns support significant morphological, developmental, and inferred dietary differentiation, and therefore generic-level distinctiveness, among Afropithecus, Morotopithecus and the Proconsul clade. An isolated M1 (UMP MORII 03'559) is morphologically dissimilar, and much smaller than the actual or inferred size of molars in UMP MORII 03'551, UMP 66-01 and UMP 62-10, supporting the presence of two hominoid taxa at Moroto II, M. bishopi and a smaller bodied proconsulid. Given the high level of body mass dimorphism inferred for Morotopithecus and other early Miocene catarrhines, the known postcrania from Moroto II could be attributable to either taxon. However, UMP MORII 03'551 and the femora UMP MORII 94'80 derive from the same stratigraphic interval, while the isolated M1 was deposited later, increasing the likelihood that the mandible and femora are from the same individual. These new fossils expand our understanding of the taxonomic and adaptive diversity of early Miocene catarrhines.
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Publication date: July 2019
Source: Journal of Human Evolution, Volume 132
Author(s): Marc R. Meyer, Scott A. Williams
Abstract
Australopitheus anamensis fossils demonstrate that craniodentally and postcranially the taxon was more primitive than its evolutionary successor Australopithecus afarensis. Postcranial evidence suggests habitual bipedality combined with primitive upper limbs and an inferred significant arboreal adaptation. Here we report on A. anamensis fossils from the Assa Issie locality in Ethiopia's Middle Awash area dated to ∼4.2 Ma, constituting the oldest known Australopithecus axial remains. Because the spine is the interface between major body segments, these fossils can be informative on the adaptation, behavior and our evolutionary understanding of A. anamensis. The atlas, or first cervical vertebra (C1), is similar in size to Homo sapiens, with synapomorphies in the articular facets and transverse processes. Absence of a retroglenoid tubercle suggests that, like humans, A. anamensis lacked the atlantoclavicularis muscle, resulting in reduced capacity for climbing relative to the great apes. The retroflexed C2 odontoid process and long C6 spinous process are reciprocates of facial prognathism, a long clivus and retroflexed foramen magnum, rather than indications of locomotor or postural behaviors. The T1 is derived in shape and size as in Homo with an enlarged vertebral body epiphyseal surfaces for mitigating the high-magnitude compressive loads of full-time bipedality. The full costal facet is unlike the extant great ape demifacet pattern and represents the oldest evidence for the derived univertebral pattern in hominins. These fossils augment other lines of evidence in A. anamensis indicating habitual bipedality despite some plesiomorphic vertebral traits related to craniofacial morphology independent of locomotor or postural behaviors (i.e., a long clivus and a retroflexed foramen magnum). Yet in contrast to craniodental lines of evidence, some aspects of vertebral morphology in A. anamensis appear more derived than its descendant A. afarensis.
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Publication date: July 2019
Source: Journal of Human Evolution, Volume 132
Author(s): Luca Fiorenza, Stefano Benazzi, Ottmar Kullmer, Giulia Zampirolo, Arnaud Mazurier, Clément Zanolli, Roberto Macchiarelli
Abstract
Tooth wear is an important feature for reconstructing diet, food processing and cultural habits of past human populations. In particular, occlusal wear facets can be extremely useful for detecting information about diet and non-masticatory behaviors. The aim of this study is to reconstruct the diet and cultural behavior of the Neanderthal specimen Regourdou 1 (Dordogne, Southern France) from the analysis of the macrowear pattern, using the occlusal fingerprint analysis method. In addition, we have also examined whether there is any association between the observed dental macrowear and mandibular bone distribution and root dentine thickness. The posterior dentition of Regourdou 1 is characterized by an asymmetric wear pattern, with the right side significantly more worn than the left. In contrast, the left lower P3 shows a more advanced wear than the right premolar, with unusual semicircular enamel wear facets. The results from occlusal fingerprint analysis of this unique pattern suggest tooth-tool uses for daily task activities. Moreover, the left buccal aspect of the mandibular cortical bone is thicker than its right counterpart, and the left P3 has a thicker radicular dentine layer than its antimere. These results show a certain degree of asymmetry in cortical bone topography and dentine tissue that could be associated with the observed dental macrowear pattern. The molar macrowear pattern also suggests that Regourdou 1 had a mixed diet typical of those populations living in temperate deciduous woodlands and Mediterranean habitats, including animal and plant foods. Although this study is limited to one Neanderthal individual, future analyses based on a larger sample may further assist us to better understand the existing relationship between mandibular architecture, occlusal wear and the masticatory apparatus in humans.
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Publication date: July 2019
Source: Journal of Human Evolution, Volume 132
Author(s): Ingrid K. Lundeen, E. Christopher Kirk
Abstract
Primates have historically been viewed as having a diminished sense of smell compared to other mammals. In haplorhines, olfactory reduction has been inferred partly based on the complexity of the bony turbinals within the nasal cavity. Some turbinals are covered in olfactory epithelium, which contains olfactory receptor neurons that detect odorants. Accordingly, turbinal number and complexity has been used as a rough anatomical proxy for the relative importance of olfactory cues for an animal's behavioral ecology. Unfortunately, turbinals are delicate and rarely preserved in fossil specimens, limiting opportunities to make direct observations of the olfactory periphery in extinct primates. Here we describe the turbinal morphology of Rooneyia viejaensis, a late middle Eocene primate of uncertain phylogenetic affinities from the Tornillo Basin of West Texas. This species is currently the oldest fossil primate for which turbinals are preserved with minimal damage or distortion. Microcomputed tomography (μCT) reveals that Rooneyia possessed 1 nasoturbinal, 4 bullar ethmoturbinals, 1 frontoturbinal, 1 interturbinal, and an olfactory recess. This pattern is broadly similar to the condition seen in some extant strepsirrhine primates but differs substantially from the condition seen in extant haplorhines. Crown haplorhines possess only two ethmoturbinals and lack frontoturbinals, interturbinals, and an olfactory recess. Additionally, crown anthropoids have ethmoturbinals that are non-bullar. These observations reinforce the conclusion that Rooneyia is not a stem tarsiiform or stem anthropoid. However, estimated olfactory turbinal surface area in Rooneyia is greater than that of similar-sized haplorhines but smaller than that of similar-sized lemuriforms and lorisiforms. This finding suggests that although Rooneyia was broadly plesiomorphic in retaining a large complement of olfactory turbinals as in living strepsirrhines, Rooneyia may have evolved somewhat diminished olfactory abilities as in living haplorhines.
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Publication date: July 2019
Source: Journal of Human Evolution, Volume 132
Author(s): Lorenzo Galletta, Nicholas B. Stephens, Ameline Bardo, Tracy L. Kivell, Damiano Marchi
Abstract
Understanding the manual abilities of fossil hominins has been a focus of palaeoanthropological research for decades. Of interest are the morphological characteristics of the thumb due to its fundamental role in manipulation, particularly that of the trapeziometacarpal joint. Considerably less attention has been given to the thumb metacarpophalangeal (MCP) joint, which plays a role in stabilizing the thumb during forceful grasps and precision pinching. In this study we use a three-dimensional geometric morphometric approach to quantify the shape of the first metacarpal head in extant hominids (Homo, Pan, Gorilla and Pongo) and six fossil hominin species (Homo neanderthalensis Tabun C1 and La Chappelle-aux-Saints, Homo naledi U.W. 101-1282, Australopithecus sediba MH2, Paranthropus robustus/early Homo SK84, Australopithecus africanus StW 418, Australopithecus afarensis A.L. 333w-39), with the aims of identifying shapes that may be correlated with human-like forceful opposition and determining if similar morphologies are present in fossil hominins. Results show that humans differ from extant great apes by having a distally flatter articular surface, larger epicondyle surface area, and a larger radial palmar condyle. We suggest that this suite of features is correlated with a lower range of motion at the MCP joint, which would enhance the thumbs ability to resist the elevated loads associated with the forceful precision grips typical of humans. Great ape genera are each differentiated by distinctive morphological features, each of which is consistently correlated with the predicted biomechanical demands of their particular locomotor and/or manipulatory habits. Neanderthals and U.W. 101-1282 fall within the modern human range of variation, StW 418, SK 84 and U.W. 88-119 fall in between humans and great apes, and A.L. 333w-39 falls within Pan variation. These results agree with those of traditional linear analyses while providing a more comprehensive quantitative basis from which to interpret the hand functional morphology of extinct hominins.
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Publication date: July 2019
Source: Journal of Human Evolution, Volume 132
Author(s): Elham Ghasidian, Saman Heydari-Guran, Marta Mirazón Lahr
Abstract
This paper aims to understand the cultural diversity among the first modern human populations in the Iranian Zagros and the implications of this diversity for evolutionary and ecological models of human dispersal through Eurasia. We use quantitative data and technotypological attributes combined with physiogeographic information to assess if the Zagros Upper Paleolithic (UP) developed locally from the Middle Paleolithic (MP), as well as to contextualize the variation in lithics from four UP sites of Warwasi, Yafteh, Pasangar, and Ghār-e Boof. Our results demonstrate (1) that the Zagros UP industries are intrusive to the region, and (2) that there is significant cultural diversity in the early UP across different Zagros habitat areas, and that this diversity clusters in at least three groups. We interpret this variation as parallel developments after the initial occupation of the region shaped by the relative geotopographical isolation of different areas of the Zagros, which would have favored different ecological adaptations. The greater similarity of lithic traditions and modes of production observed in the later phases of the UP across all sites indicates a marked increase in inter-group contact throughout the West-Central Zagros mountain chain. Based on the chronological and geographical patterns of Zagros UP variability, we propose a model of an initial colonization phase leading to the emergence of distinct local traditions, followed by a long phase of limited contact among these first UP groups. This has important implications for the origins of biological and cultural diversity in the early phases of modern human colonization of Eurasia. We suggest that the mountainous arc that extends from Anatolia to the Southern Zagros preserves the archaeological record of different population trajectories. Among them, by 40 ka, some would have been transient, whereas others would have left no living descendants. However, some would have led to longer term local traditions, including groups who share ancestry with modern Europeans and modern East/Southeast Asians.
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Publication date: July 2019
Source: Journal of Human Evolution, Volume 132
Author(s): Ignacio A. Lazagabaster
Abstract
Stable carbon isotope studies suggest that early hominins may have diversified their diet as early as 3.76 Ma. Early Pliocene hominins, including Australopithecus anamensis, had diets that were dominated by C3 resources while Late Pliocene hominins, including Australopithecus afarensis—a putative descendant of A. anamensis—had diets that included both C3 and C4 resources. It has been hypothesized that the expansion of C4 grasslands in eastern Africa during the Pliocene could have prompted hominins to incorporate C4 resources in their diets. However, dental microwear analyses suggest that diet diversification did not involve changes in the mechanical properties of the foods consumed. To provide contextual and comparative information on this issue, the diet of suids from the A. anamensis site of Kanapoi and the A. afarensis site of Hadar is investigated. Using dental microwear texture analyses, it is shown that despite significant dietary overlap, there is evidence for dietary niche partitioning among suids. Based on comparisons with the diet of extant African suids, it is inferred that Nyanzachoerus pattersoni (n = 21) was a mixed feeder, Nyanzachoerus jaegeri (n = 4) and Notochoerus euilus (n = 61) were habitual grazers, and Kolpochoerus afarensis (n = 34) had a broad diet that included hard brittle foods and underground resources. The dental microwear of Ny. pattersoni and Ny. jaegeri/No. euilus do not differ significantly between Kanapoi and Hadar. Most differences are driven by K. afarensis, a suid absent at Kanapoi but present at Hadar. Food availability probably differed between Hadar and Kanapoi, and it is likely that A. afarensis did not exploit some of the foods (e.g., underground resources) consumed by suids. It is hypothesized that despite the incorporation of C4 resources in the diet, a significant dietary change towards flexible diets in the hominin lineage had yet to come.
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Publication date: July 2019
Source: Journal of Human Evolution, Volume 132
Author(s): Laurent Pallas, Guillaume Daver, Hassane T. Mackaye, Andossa Likius, Patrick Vignaud, Franck Guy
Abstract
Central Africa is known as a major center of diversification for extant Old World Monkeys (OWM) and yet has a poorly documented fossil record of monkeys. Here we report a new colobine monkey (Cercopithecoides bruneti sp. nov.) from the Central African hominin-bearing fossiliferous area of Toros-Menalla, Chad at ca. 7 Ma. In addition to filling a gap in the spatial and temporal record of early OWM evolutionary history, we assess the ecomorphological diversity of early OWM by providing evidence on the onset of a folivorous diet and a partial reacquisition of terrestrial locomotor habits among Miocene colobines. We also support the phylogenetic affinities of the genus Cercopithecoides among the stem group of the extant African colobine monkeys.
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Publication date: July 2019
Source: Journal of Human Evolution, Volume 132
Author(s): Desalegn Chala, Christian Roos, Jens-Christian Svenning, Dietmar Zinner
Abstract
Baboons (genus Papio) have been proposed as a possible analogous phylogeographic model for intra-African dispersal of hominins during the Pleistocene. Previous studies of the genus reveal complex evolutionary dynamics including introgressive hybridization and, as for hominins, it has been hypothesized that past climate change has been a major driver in their evolutionary history. However, how historical climate changes affected the distribution and extent of baboon habitats is not clear. We therefore employed three ecological niche modeling algorithms (maximum entropy model: MaxEnt; general additive model: GAM; gradient boosting model: GBM) to map suitable habitat of baboons at both genus and species levels under two extreme late-Quaternary climates: current (warm period) and Last Glacial Maximum (LGM, cold period). The three model algorithms predicted habitat suitabilities for the baboon species with high accuracy, as indicated by AUC values of 0.83–0.85 at genus level and ≥0.90 for species. The results suggest that climate change from LGM to current affected the distribution and extent of suitable habitats for the genus Papio only slightly (>80% of the habitat remained suitable). However, and in contrast to our expectation for ecological generalists, individual species have been differentially affected. While P. ursinus and P. anubis lost some of their suitable habitats (net loss 25.5% and 13.3% respectively), P. kindae and P. papio gained large portions (net gain >62%), and P. cynocephalus and P. hamadryas smaller portions (net gain >20%). Overlap among the specific realized climate niches remained small, suggesting only slight overlap of suitable habitat among species. Results of our study further suggest that shifts of suitable habitats could have led to isolation and reconnection of populations which most likely affected gene flow among them. The impact of historic climate changes on baboon habitats might have been similar for other savanna living species, such as hominins.
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