Michael Berthaume

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• Mechanical Engineering Ph.D.
• Reader/Associate professor at King's College London

The fabella is a sesamoid bone located behind the lateral femoral condyle. It is common in non‐human mammals, but the prevalence rates in humans vary from 3 to 87%. Here, we calculate the prevalence of the fabella in a Korean population and investigate possible temporal shifts in prevalence rate. A total of 52.83% of our individuals and 44.34% of o...

In recent decades, funding agencies, institutes and professional bodies have recognized the profound benefits of transdisciplinarity in tackling targeted research questions. However, once questions are answered, the previously abundant support often dissolves. As such, the long-term benefits of these transdisciplinary approaches are never fully ach...

Biomechanics is the set of tools that explain organismal movement and mechanical behavior and links the organism to the physicality of the world. As such, biomechanics can relate behaviors and culture to the physicality of the organism. Scale is critical to biomechanical analyses, as the constitutive equations that matter differ depending on the sc...

Sesamoids are variably present skeletal elements found in tendons and ligaments near joints. Variability in sesamoid size, location and presence/absence is hypothesized to enable skeletal innovation, yet sesamoids are often ignored. Three knee sesamoids—the cyamella, medial fabella and lateral fabella—are present in primates, but we know little abo...

Like many mammals, grasshoppers (infraorder Acrididea) chew using molariform structures. Despite decades of research on mammals, little is known about grasshopper molar form and how it relates to grasshopper feeding biomechanics, diet, dietary ecology and evolution. Here, we develop a method for quantifying molar form and apply it to two species of...

Midfacial morphology varies between hominoids, in particular between great apes and humans for which the face is small and retracted. The underlying developmental processes for these morphological differences are still largely unknown. Here, we investigate the cellular mechanism of maxillary development (bone modelling, BM), and how potential chang...

Background When dealing in global health, it is crucial to have a comprehensive understanding of community demographics and needs. From 1983-2009, a 26-year ethnic civil conflict devastated Sri Lanka, disproportionately affecting people living in the north and creating a large amputee population. Here, we use routinely collected prosthetic and orth...

Enamel mechanical properties vary across molar crowns, but the relationship among mechanical properties, tooth function, and phylogeny are not well understood. Fifteen primate lower molars representing fourteen taxa (catarrhine, n = 13; platyrrhine, n = 1) were sectioned in the lingual-buccal plane through the mesial cusps. Gradients of enamel mech...

Dental topographic analysis has proved a valuable tool for quantifying dental morphology. Established workflows often use proprietary software for pre-processing dental surfaces, rendering the method expensive and inaccessible to many. This study explores the use of freeware pre-processing alternatives. We tested 4 decimation tools and 13 smoothing...

Background: The International Organization for Standardization (ISO) 10328 standards are used to verify the safety of lower limb prosthetic devices. However, the ISO 10328 tests are performed in sterile laboratory settings and do not account for environmental or sociocultural factors associated with prosthetic use. Most locally manufactured prosth...

Treating open fractures in long bones can be challenging and if not performed properly can lead to poor outcomes such as mal/non-union, deformity, and amputation. One of the most common methods of treating these fracture types is temporary external fixation followed by definitive fixation. The shortage of high-quality affordable external fixators i...

Size and shape variation of molar crowns in primates plays an important role in understanding how species adapted to their environment. Gorillas are commonly considered to be folivorous primates because they possess sharp cusped molars which are adapted to process fibrous leafy foods. However, the proportion of fruit in their diet can vary signific...

Size and shape variation of molar crowns in primates plays an important role in understanding how species adapted to their environment. Gorillas are commonly considered to be folivorous primates because they possess sharp cusped molars which are adapted to process fibrous leafy foods. However, the proportion of fruit in their diet can vary signific...

Diet is a driving force in human evolution. Two species of Plio-Pleistocene hominins, Paranthropus robustus and Australopithecus africanus , have derived craniomandibular and dental morphologies which are often interpreted as P. robustus having a more biomechanically challenging diet. While dietary reconstructions based on dental microwear generall...

The distal femoral metaphyseal surface presents dramatically different morphologies in juvenile extant hominoids—humans have relatively flat metaphyseal surfaces when compared with the more complex metaphyseal surfaces of apes. It has long been speculated that these different morphologies reflect different biomechanical demands placed on the growth...

The cyamella is a rare, generally asymptomatic, knee sesamoid bone located in the proximal tendon of the popliteal muscle. Only two studies have investigated cyamella presence/absence in humans, putting ossified prevalence rates at 0.57%–1.8%. We aim to (a) determine cyamella prevalence in a Korean population, (b) examine coincident development of...

Rapid developments in prosthetics, orthotics and wheelchair technology have increased clinical research and development initiatives worldwide. Testing technology involving human subjects / participants creates ethical concerns that are under-explored and become a critical issue for prosthetists, orthotists, researchers and their clients, especially...

The fabella is a sesamoid bone usually located in the tendon of the lateral head of the gastrocnemius muscle, behind the knee joint. Prevalence rates in human populations vary widely with an average of 42.5% people having a fabella. Clinically, it is associated with a number of knee ailments, most notably the osteoarthritis of the knee and generali...

Introduction The fabella is a sesamoid bone embedded in the tendon of the lateral head of the gastrocnemius. It is the only bone in the human body to increase in prevalence in the last 100 years. As the fabella can serve as an origin/insertion for muscles, tendons, and/or ligaments (e.g., the oblique popliteal and fabellofibular ligaments), tempora...

The Fabella is a sesamoid bone usually located inside the tendon of the lateral head of the gastrocnemius muscle behind the knee joint. Prevalence rates in human populations vary widely with an average of 42.54% people having a Fabella. Clinically, it is associated with a number of knee ailments, most notably the osteoarthritis of the knee, and wit...

Diet plays an incontrovertible role in primate evolution, affecting anatomy, growth and development, behavior, and social structure. It should come as no surprise that a myriad of methods for reconstructing diet have developed, mostly utilizing the element that is not only most common in the fossil record but also most pertinent to diet: teeth. Twe...

Available open access here https://onlinelibrary.wiley.com/doi/full/10.1111/joa.13091 The fabella is a sesamoid bone located in the gastrocnemius behind the lateral femoral condyle. In humans, fabellae are 3.5 times more common today than they were 100 years ago, with prevalence rates varying between and within populations. In particular, fabella...

Dental topography is a widely used method for quantifying dental morphology and inferring dietary ecology in animals. Differences in methodology have brought into question the comparability of different studies. Using primate mandibular second molars, we investigated the effects of mesh preparation parameters smoothing, cropping, and triangle count...

Five-way ANOVA results. Results from five-way ANOVA. (XLSX)

Transformation equations. Transformation equations for smoothing and cropping. (XLSX)

Descriptive statistics. Descriptive statistics for data. (XLSX)

One-way ANOVA results. Results from one-way ANOVAs. (XLSX)

Correlations among metrics. Correlations between topographic variables. (XLSX)

Statistics for slopes and intercepts. ANOVAS, Tukey HSDs, and DFAs for intercepts and slopes. (XLSX)

Boxplots. 880 boxplots for topographic values. (PPTX)

Boxplots for slopes and intercepts. . Boxplots for DNE and OPCR slopes and intercepts vs. diet. (PPTX)

All data dental topography. Raw data for analyses. (XLSX)

Linear plots. Linear plots, effect of triangle count and resolution on topographic variables. (PPTX)

Tukey HSD visualization. Graphical representations of Tukey HSD results. (PPTX)

Tukey HSD results. Results for Tukey HSD analyses. (XLSX)

Slopes and intercepts. Slopes and intercepts of DNE and OPCR vs. triangle count and resolution. (XLSX)

Tukey HSD visualization. Tukey HSD visualized for triangle count and resolution. (PPTX)

Recently, ambient occlusion, quantified through portion de ciel visible (PCV) was introduced as a method for quantifying dental morphological wear resistance and reconstructing diet in mammals. Despite being used to reconstruct diet and investigate the relationship between dental form and function, no rigorous analysis has investigated the correlat...

Raw data for analyses. Raw PCV values used for analyses. (CSV)

Averages and standard deviations. Descriptive statistics for PCV values. (CSV)

Though late Middle Pleistocene in age, Homo naledi is characterized by a mosaic of Australopithecus-like (e.g., curved fingers, small brains) and Homo-like (e.g., elongated lower limbs) traits, which may suggest it occupied a unique ecological niche. Ecological reconstructions inform on niche occupation, and are particularly successful when using d...

Dental topography reflects diet accurately in several extant and extinct mammalian clades. However, dental topographic dietary reconstructions have high success rates only when closely related taxa are compared. Given the dietary breadth that exists among extant apes and likely existed among fossil hominins, dental topographic values from many spec...

Ostrich-like birds (Palaeognathae) show very little taxonomic diversity while their sister taxon (Neognathae) contains roughly 10000 species. The main anatomical differences between the two taxa are in the crania. Palaeognaths lack an element in the bill called the lateral bar that is present in both ancestral theropods and modern neognaths, have t...

Australopithecus sediba has been hypothesized to be a close relative of the genus Homo. Here we show that MH1, the type specimen of A. sediba, was not optimized to produce high molar bite force and appears to have been limited in its ability to consume foods that were mechanically challenging to eat. Dental microwear data have previously been inter...

Supplementary Figures 1-6, Supplementary Tables 1-4 and Supplementary Reference

Dental topography has successfully linked disparate tooth shapes to distinct dietary categories, but not to masticatory efficiency. Here, I investigate the relationship between four dental topographic metrics and brittle food item breakdown efficiency during compressive biting using a parametric finite element model of a bunodont molar. Food item b...

Interdisciplinary research has benefitted the fields of anthropology and engineering for decades: a classic example being the application of material science to the field of feeding biomechanics. However, after decades of research, discordances have developed in how mechanical properties are defined, measured, calculated, and used due to disharmoni...

Legg-Calvé-Perthes' (Perthes') disease is a developmental disease of the hip joint that may result in numerous short and long term problems. The aetiology of the disease remains largely unknown, but the mechanism is believed to be vascular and/or biomechanical in nature. There are several anatomical characteristics that tend to be prevalent in chil...

Over 40 years ago, Clifford Jolly noted different ways in which Hadropithecus stenognathus converged in its craniodental anatomy with basal hominins and with geladas. The Malagasy subfossil lemur Hadropithecus departs from its sister taxon, Archaeolemur, in that it displays comparatively large molars, reduced incisors and canines, a shortened rostr...

The African Plio-Pleistocene hominins known as australopiths evolved derived craniodental features frequently interpreted as adaptations for feeding on either hard, or compliant/tough foods. Among australopiths, Paranthropus boisei is the most robust form, exhibiting traits traditionally hypothesized to produce high bite forces efficiently and stre...

Research Cite this article: Berthaume MA, Dumont ER, Godfrey LR, Grosse IR. 2014 The effects of relative food item size on optimal tooth cusp sharpness during brittle food item processing. Teeth are often assumed to be optimal for their function, which allows researchers to derive dietary signatures from tooth shape. Most tooth shape analyses norma...

Mammalian molars have undergone heavy scrutiny to determine correlates between morphology and diet. Here, the relationship between one aspect of occlusal morphology, tooth cusp radius of curvature (RoC), and two broad dietary categories, folivory and frugivory, is analyzed in apes. Based on previous dental topography studies, I hypothesize that the...

An ongoing debate concerning Neandertal ecology is whether or not they utilized long range weaponry. The anteroposteriorly expanded cross-section of Neandertal humeri have led some to argue that their humeri were adapted to thrusting hunting weapons, while the rounder cross-section of Late Upper Paleolithic humeri suggests modern humans threw their...

Mammalian molars have undergone heavy scrutiny to determine correlates between morphology and diet. Here, the relationship between one aspect of occlusal morphology, tooth cusp radius of curvature (RoC), and two broad dietary categories, folivory and frugivory, is analyzed in apes. The author hypothesizes that there is a relationship between tooth...

It has been hypothesized that the extensively overlapping temporal and parietal bones of the squamosal sutures in Paranthropus boisei are adaptations for withstanding loads associated with feeding. Finite element analysis (FEA) was used to investigate the biomechanical effects of suture size (i.e., the area of overlap between the temporal and parie...

It is common to assume that teeth are optimal for their function, but few studies evaluate the impact of the size and shape of food items on tooth function. Here we test the hypothesis that the size and shape of food items does impact the performance of one specific tooth morphology; notch angle, the angle between two cusps or teeth. Many animals h...

Tooth cusp radius of curvature (RoC) has been hypothesized to play an important role in food item breakdown, but has remained largely unstudied due to difficulties in measuring and modeling RoC in multicusped teeth. We tested these hypotheses using a parametric model of a four cusped, maxillary, bunodont molar in conjunction with finite element ana...

As methods for engineering data acquisition improve, methods for storing, generating knowledge from, and sharing that data for efficient reuse have become more important. Knowledge management in the engineering community can greatly benefit from advancements made in knowledge management in biology. The biological community has already made progress...

Tooth cusp sharpness, measured by radius of curvature (RoC), has been predicted to play a significant role in brittle/hard food item fracture. Here, we set out to test three existing hypotheses about this relationship: namely, the Blunt and Strong Cusp hypotheses, which predict that dull cusps will be most efficient at brittle food item fracture, a...

Recent biomechanical analyses examining the feeding adaptations of early hominins have yielded results consistent with the hypothesis that hard foods exerted a selection pressure that influenced the evolution of australopith morphology. However, this hypothesis appears inconsistent with recent reconstructions of early hominin diet based on dental m...

The basal bifurcation in the phylogeny of modern birds is between ostrich-like birds (ratites and tinamous; Palaeognathae) and all other birds (Neognathae). Most differences between the Palaeognathae and Neognathae lie in the reduction or loss of the ability to fly, but the crania of palaeognaths are also more robust and more fenestrated than those...

Finite element models (FEMs) of biological systems are becoming widely used in evolutionary biomechanics. The material properties of bone are fundamental inputs for such models, but these are difficult to measure, and are stochastic in nature, anisotropic and spatially non-homogeneous. To date, no formal probabilistic analysis techniques have been...

Hypotheses regarding patterns of stress, strain and deformation in the craniofacial skeleton are central to adaptive explanations for the evolution of primate craniofacial form. The complexity of craniofacial skeletal morphology makes it difficult to evaluate these hypotheses with in vivo bone strain data. In this paper, new in vivo bone strain dat...

Tooth profile plays an important role in interpretations of the functional morphology of extinct species. We tested hypotheses that australopith occlusal morphology influences the fracture force required to crack large, hard food items using a combination of physical testing and finite element analysis (FEA). We performed mechanical experiments sim...