Monkey next to negative photos of serial sections of the myosin heavy chain profile of a monkey chewing muscle

Taylor Lab

The Musculoskeletal Design and Performance Lab studies musculoskeletal anatomy, physiology, biomechanics, and the evolution of feeding-system morphology with the goal of understanding the factors that drive evolutionary changes in craniofacial form and function.

Principal Investigator

Taylor, Andrea

Andrea B. Taylor, Ph.D. is Professor in the Department of Foundational Biomedical Sciences at Touro University California and Director of the Musculoskeletal Design and Performance Lab. She is also a Research Associate in the Department of Anthropology, Institute for Biodiversity Science and Sustainability, California Academy of Sciences, and Adjunct Professor in the Department of Orthopaedic Surgery, Duke University School of Medicine.

Read Full Biography

Projects Overview

Our research uses experimental and comparative approaches to model muscle and bone mechanics, test hypotheses of feeding-system morphology, feeding behavior and diet, and gain insights into the factors that led to species divergence in primates. Current projects focus on testing functional and evolutionary hypotheses of skeletal muscle architecture and fiber types in primate chewing muscles, relationships between feeding-system morphology, feeding behavior, and feeding performance during growth and development, and the biomechanics and evolution of mandibular form in living primates and early human ancestors.

Serial sections showing the four major myosin heavy chain (MHC) isoforms expressed in sooty mangabey superficial masseter. A) MHC-1, B) MHC-α, C) MHC-2, and D) MHC-M (masticatory myosin). Note the abundance of hybrid fibers (co-staining of fibers expressing MHC-1, MHC-alpha, and MHC-2) and counterstaining between MHC-1 and MHC-M.

Chewing Muscle Fiber Types

How do fiber types and their contractile properties such as shortening velocity, endurance, and tension help fine tune primate chewing muscles for specific tasks? Our comparative work focuses on identifying the major myosin heavy chain (MHC) isoforms expressed within and between primate chewing muscles, how MHC patterns of expression compare with those of nonprimate mammals, and their functional relationships to primate feeding behavior and diet.

Learn More
Top: Skeletal muscle fibers may be oriented in parallel (A) or at an angle (B) relative to the axis of force generation. For muscles of comparable volume, parallel-fibered muscles pack in fewer, but longer fibers, making them well-suited for producing large excursions, whereas pinnate-fibered muscles pack in shorter, but more fibers, and thus are designed for producing large muscle forces. Middle: The masseter (C) and medial pterygoid (D) are multipinnate (i.e., fibers oriented in multiple directions), whereas the temporalis (E) is bipinnate (i.e., fibers oriented in two directions). Upper row represents whole muscles, lower row represents corresponding muscles in cross-section. All are left-sided muscles. Bottom: Fiber length and orientation have significant functional implications for muscle stretch/gape and muscle and bite force related to feeding (F, G) and for gape behaviors unrelated to feeding such as wide-mouth display (H).

Chewing Muscle Fiber Architecture

How are the jaw movements and occlusal forces associated with feeding behavior and diet facilitated or limited by jaw-muscle architecture? We examine architectural scaling patterns of the chewing muscles, their interaction with other parts of the masticatory apparatus, and their impact on how primates meet their energy demands. We use the comparative approach to understand form-function relationships between jaw-muscle architecture, muscle leverage, and the dentition in living primates and use these results to draw inferences about feeding behavior and diet in extinct species.

Learn More
A surface file (.ply) of a sooty mangabey skull.

Mandibular Biomechanics and Evolution

This project uses finite element analysis to investigate the spatial and mechanical determinants of mandibular form and the extent to which these factors track changes in feeding behavior and diet in extant apes and humans, and in our early hominin ancestors (Australopithecus).

Learn More

Recent News

Check out our review paper published in the March 2025 issue of Evolutionary Anthropology.

Jasmine Sun, COM OMS1, joins the Lab!

The Lab hosts UC Berkeley students through the Cal Job Shadow Program.

Faculty, Staff & Students

Amanda Smith, Ph.D., is Assistant Professor in the Department of Foundational Biomedical Sciences at TUC and co-PI of the Musculoskeletal Design and Performance Lab. She uses advanced medical imaging and reconstruction, 3D modeling, and structural analysis to test hypotheses about feeding-system anatomy and performance and to address clinical problems such as the mechanics of alveolar clefts and repair and orbital fracture mechanics.

Lauren Taylor smiling while working on computer in Taylor Lab

Lauren Taylor, BA, is a Research Lab Assistant. She oversees the lab and assists with data collection and analysis and training students.

Jasmine Sun smiling while working on computer in Taylor Lab

Student Doctor Jasmine Sun, MS, is a COM student with interests in head and neck anatomy. She is studying fiber types of the jaw-adductor muscles in strepsirrhine primates.