Evolution of lumbar lordosis
Lumbar lordosis is a crucial adaptation for bipedalism. Fossil estimates of lumbar curvature show that lordosis was likely present in the spines of even the earliest hominins. Researchers believe the main functional role of lordosis is to support and stabilize the mass of a bipedal upper body, decreasing the costs of upright posture. However, there is considerable variation in lordosis between and within extant and extinct hominin groups, and interpreting such variations in lumbar curvature is a challenge because the function of lordosis remains poorly understood.
Why are there variations in lordosis among humans? Does lordosis serve other biomechanical functions? What factors explain variations in lordosis, and what are the functional consequences of these variations? Is lower back pain a necessary consequence of bipedalism or a mismatch condition caused by low levels of activity and weak, unstable back tissues today? These are a few of the questions addressed in my thesis research.
Recent publications/conference presentations on this topic include:
Castillo ER, Lieberman DE. (2019) In vivo bending deformation of the human lumbar spine during axial loading: Implications for hominin postural adaptation. American Association of Physical Anthropology 168(S68): 37.
Castillo ER, Lieberman DE. (2018) Lordosis variability and shock transmission in the human lumbar spine. Society for Comparative and Integrative Biology 58: E290-E290. [poster presentation] abstract
Castillo ER, Lieberman DE. (2018) Shock attenuation in the human lumbar spine during walking and running. Journal of Experimental Biology 221(9). DOI: 10.1242/jeb.177949. pdf
Castillo ER, Lieberman DE. (2017) Lordosis variability and shock attenuation in the hominin lumbar spine. American Journal of Physical Anthropology 162(S64): 139. [invited symposium] abstract
Castillo ER, Hsu C, Mair RW, Lieberman DE. (2017) Testing biomechanical models of human lumbar lordosis variability. American Journal of Physical Anthropology 163(1): 110-121. DOI: 10.1002/ajpa.23189. pdf
Castillo, ER. (2017) The Evolution and Function of Human Lumbar Lordosis Variability. Doctoral dissertation, Harvard University, Graduate School of Arts & Sciences. pdf
Hsu C, Castillo E, Lieberman D. (2015) The relationship between trunk muscle strength and flexibility, intervertebral disc wedging, and human lumbar lordosis. The Harvard Undergraduate Research Journal 8(1): 35-41. pdf
Castillo ER, Lieberman DE. (2015) Lower back pain. Evolution, Medicine, and Public Health 1: 2-3. DOI: 10.1093/emph/eou034. pdf
Castillo ER, Lieberman DE. (2014) In vivo axial loading and lumbar deformation in rural and urban adults from western Kenya. Northeast Regional Joint Meeting of the Division of Vertebrate Morphology and Division of Comparative Biomechanics, Society for Integrative and Comparative Biology. [podium presentation]
Castillo ER, Sang M, Sigei T, Ojiambo R, Pitsiladis Y, Lieberman DE. (2014) Effects of physical activity on sex differences in lumbar lordosis development in rural and urban Kenyan population. Annual meetings of the American Association of Physical Anthropology. American Journal of Physical Anthropology 153 (S58): 92. [podium presentation] abstract