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Testing Dietary Hypotheses of East African Hominines Using Buccal Dental Microwear Data - PubMed

  • ️Fri Jan 01 2016

Testing Dietary Hypotheses of East African Hominines Using Buccal Dental Microwear Data

Laura Mónica Martínez et al. PLoS One. 2016.

Abstract

There is much debate on the dietary adaptations of the robust hominin lineages during the Pliocene-Pleistocene transition. It has been argued that the shift from C3 to C4 ecosystems in Africa was the main factor responsible for the robust dental and facial anatomical adaptations of Paranthropus taxa, which might be indicative of the consumption of fibrous, abrasive plant foods in open environments. However, occlusal dental microwear data fail to provide evidence of such dietary adaptations and are not consistent with isotopic evidence that supports greater C4 food intake for the robust clades than for the gracile australopithecines. We provide evidence from buccal dental microwear data that supports softer dietary habits than expected for P. aethiopicus and P. boisei based both on masticatory apomorphies and isotopic analyses. On one hand, striation densities on the buccal enamel surfaces of paranthropines teeth are low, resembling those of H. habilis and clearly differing from those observed on H. ergaster, which display higher scratch densities indicative of the consumption of a wide assortment of highly abrasive foodstuffs. Buccal dental microwear patterns are consistent with those previously described for occlusal enamel surfaces, suggesting that Paranthropus consumed much softer diets than previously presumed and thus calling into question a strict interpretation of isotopic evidence. On the other hand, the significantly high buccal scratch densities observed in the H. ergaster specimens are not consistent with a highly specialized, mostly carnivorous diet; instead, they support the consumption of a wide range of highly abrasive food items.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. SEM images of post-mortem damaged teeth that were not included in the buccal microwear analyses.

(a) LP4 OH-65 with patina layers covering the microwear features. (b) LM1 KNM-ER-1171 with perykimata—growth lines—and enamel prisms caused by chemical erosion. (c) RP4 OH-5 with post-mortem physical abrasion caused by rolling over sediments. Scale line is 200 μm.

Fig 2
Fig 2. Well-preserved buccal microwear surfaces in which buccal striations could be measured.

(a) LP4 OH-69 Homo habilis. (b) RM1 KNM-WT-15000 Homo ergaster. (c) LM1 Peninj Paranthropus boisei. Scale line is 200 μm.

Fig 3
Fig 3. Box plots of microwear total striation density and average striation length by species.

The whiskers show the minimum and maximum values (excluding outliers). The box includes the 25–75 percentiles. Both the median values (lines within the boxes) and means (yellow dots) are shown for the total striation density (NT) and length (XT) by species (sample sizes are indicated in brackets). For the outliers the specimen reference numbers are shown.

Fig 4
Fig 4. Plot of DF1 on DF2 derived from the Linear Discriminant Analysis of the buccal microwear variables of the hominin groups studied.

Plot of the first two discriminant functions (DF1 x axis, DF2 y axis), derived from the microwear variables (ranked data) for the hominines samples studied (Paranthropus aethiopicus brown, Paranthropus boisei beige, Homo habilis cyan, Homo ergaster red), that explain 93,8% of the total variance (55.9% and 37.9%, respectively). The ellipses show one standard deviation of the sample means (68% confidence interval of the sample). The blue lines represent the loadings of the microwear variables on the discriminant functions. The analysis was made with PAS v. 3.

Fig 5
Fig 5. Plot of DF1 on DF2 derived from the Linear Discriminant Analysis Analysis of the hominines studied along with all the comparative samples.

Plot of the first two discriminant functions (DF1 x axis, DF2 y axis), derived from the microwear variables (ranked data) for all the specimens studied and the comparative collections, that explain 73,66% of the total variance (57,25% and 16,41%, respectively). The circles represent the 95% confidence intervals of the group centroids assuming equality of covariance matrices (the size of the circle depend on the sample sizes). The red lines indicate the correlations between the variables considered and the two functions shown. The analysis was made with XLSTAT v. 2015.

Fig 6
Fig 6. Phenetic dendrogram of similarities among group centroids of all the samples considered.

The dissimilarities among groups were measured using Fisher's distance derived from the Linear Discriminant Analysis of all the microwear variables (ranked data) for all groups considered. The diagonal dissimilarity matrix was used to derive a hierarchical cluster analysis using an unweighted average agglomeration method in XLSTAT v. 2015.

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References

    1. Bamford MK, Stanistreet IG, Stollhofen H, Albert RM. Late pliocene grassland from Olduvai Gorge, Tanzania. Palaeogeogr Palaeoclimatol Palaeoecol. 2008;257: 280–293.
    1. Behrensmeyer A, Todd N, Potts R, McBrinn G. Late pliocene faunal turnover in the turkana basin, Kenya and Ethiopia. Science. 1997;278: 1589–1594. - PubMed
    1. Bobe R, Behrensmeyer AK. The expansion of grassland ecosystems in Africa in relation to mammalian evolution and the origin of the genus Homo. Palaeogeogr Palaeoclimatol Palaeoecol. 2004;207: 399–420.
    1. Bobe R, Behrensmeyer AK, Chapman RE. Faunal change, environmental variability and late pliocene Hominin evolution. J Hum Evol. 2002;42: 475–497. 10.1006/jhev.2001.0535 - DOI - PubMed
    1. Cerling TE. Development of grasslands and savannas in East Africa during the neogene. Palaeogeogr Palaeoclimatol Palaeoecol. 1992;97: 241–247.

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Grants and funding

This research was funded by the Spanish "Ministerio de Ciencia e Innovación" (http://www.idi.mineco.gob.es/portal/site/MICINN/), grant numbers CGL2011-22999 and CGL2014-52611-C2-1-P, both to APP. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.