The Masticatory Apparatus of Humans (Homo sapiens): Evolution and Comparative Functional Morphology. In: Bels V, Whishaw IQ, editors. Feeding in Vertebrates. Cham: Springer International Publishing; 2019. pp. 831-65. [DOI: 10.1007/978-3-030-13739-7_21]

Postnatal growth and spatial conformity of the cranium, brain, eyeballs and masseter muscles in the macaque (Macaca mulatta)

Spatial growth constraints in the head region can lead to coordinated patterns of morphological variation that pleiotropically modify genetically defined phenotypes as the tissues compete for space. Here we test for such architectural modifications during rhesus macaque (Macaca mulatta) postnatal ontogeny. We captured cranium and brain shape from 153 MRI datasets spanning 13 to 1090 postnatal days and tested for patterns of covariation with measurements of relative brain, eyeball, and masseter muscle size as well as callosal tract length. We find that the shape of the infant (<365 days) macaque cranium was most closely aligned to masseter muscle and brain size measured relative to face size. Infant brain and juvenile (365-1090 days) cranium shape were more closely linked with brain size relative to basicranium and face size. Meanwhile, the juvenile macaque brain shape was dominated by the size of the brain relative to that of the basicranium. Associations with relative eyeball size and commissural tract lengths were weaker. Our results are consistent with a spatial-packing regime operating during postnatal macaque ontogeny, in which relative growth of the masseter, face and basicranium have a greater influence than brain growth on the overall shape of the cranium and brain.

Hypercementosis in Late Pleistocene Homo sapiens fossils from Klasies River Main Site, South Africa

OBJECTIVE

To examine early Homo sapiens fossils from the Late Pleistocene site of Klasies River Main Site, South Africa for evidence of hypercementosis. The specimens represent seven adult individuals dated to between 119,000 and 58,000 years ago. These observations are contextualized in relation to the incidences of hypercementosis among recent human populations and fossil human samples and the potential etiologies of hypercementosis.

DESIGN

The fossils were investigated utilizing micro-CT and nano-CT scanning to visualize and measure cementum apposition on permanent incisor, premolar and molar roots. Cementum thickness was measured at mid-root level, and the volume of the cementum sleeve was calculated for the two fossil specimens that display marked hypercementosis.

RESULTS

Two of the fossils display no evidence of cementum hypertrophy. Three exhibit moderate cementum thickening, barely attaining the quantitative threshold for hypercementosis. Two evince marked hypercementosis. One of the Klasies specimens with marked hypercementosis is judged to be an older individual with periapical abscessing. The second specimen is a younger adult, and seemingly similar in age to other Klasies fossils that exhibit only minimal cementum apposition. However, this second specimen exhibits dento-alveolar ankylosis of the premolar and molars.

CONCLUSIONS

These two fossils from Klasies River Main Site provide the earliest manifestation of hypercementosis in Homo sapiens.

Functional and phylogenetic variation in anthropoid incisor size

OBJECTIVES

Previous studies have shown that frugivorous anthropoids have wider incisors than folivores relative to body mass, and that catarrhines have relatively wider incisors than platyrrhines. This study reexamines these contrasts using mandibular length as a biomechanical standard to quantify relative incisor width.

MATERIALS AND METHODS

Dental, mandibular, and body-mass data for 86 anthropoid species were taken from the literature. Incisor width was size-adjusted using shape ratios, with mandibular length and body mass as the denominators. Dietary and phylogenetic effects were examined using phylogenetic generalized least squares.

RESULTS

Mandible-based ratios provide a signal that is very similar to the one derived from ratios computed using body mass. Frugivores have relatively wider incisors than folivores, as expected. There is limited support for a stronger dietary effect in platyrrhines when mandible-based ratios are used, but neither type of ratio indicates an overall difference between platyrrhines and catarrhines.

DISCUSSION

Although both ratios support a link between incisor size and diet, there is some evidence indicating that mandible-based ratios are more sensitive to dietary variation at smaller phylogenetic scales. Understanding why the signals from the two ratios diverge at such scales may help clarify the functional significance of variation in incisor width. The results of this study undermine the view that platyrrhines, as a group, tend to have narrower incisors than catarrhines, regardless of diet. Instead, the difference between the two clades noted in previous studies can be explained by greater incisor functional diversity in platyrrhines.

Molecular Mechanism of Functional Ingredients in Barley to Combat Human Chronic Diseases

Barley plays an important role in health and civilization of human migration from Africa to Asia, later to Eurasia. We demonstrated the systematic mechanism of functional ingredients in barley to combat chronic diseases, based on PubMed, CNKI, and ISI Web of Science databases from 2004 to 2020. Barley and its extracts are rich in 30 ingredients to combat more than 20 chronic diseases, which include the 14 similar and 9 different chronic diseases between grains and grass, due to the major molecular mechanism of six functional ingredients of barley grass (GABA, flavonoids, SOD, K-Ca, vitamins, and tryptophan) and grains (β-glucans, polyphenols, arabinoxylan, phytosterols, tocols, and resistant starch). The antioxidant activity of barley grass and grain has the same and different functional components. These results support findings that barley grain and its grass are the best functional food, promoting ancient Babylonian and Egyptian civilizations, and further show the depending functional ingredients for diet from Pliocene hominids in Africa and Neanderthals in Europe to modern humans in the world. This review paper not only reveals the formation and action mechanism of barley diet overcoming human chronic diseases, but also provides scientific basis for the development of health products and drugs for the prevention and treatment of human chronic diseases.