From far away, the top of a leaf looks like one seamless surface; however, up close, that smooth exterior is actually made up of a patchwork of cells in a variety of shapes and sizes. Interested in how these cells individually take on their own unique forms, a Caltech team sought to pinpoint the shape-controlling factors in pavement cells, which are puzzle-piece-shaped epithelial cells found on the leaves of flowering plants.
“We wanted to look at these historically important events and further our understanding of the tangible human impacts they had on the Cherokee people,” says Dr. Ann Ross, a prof. of anthropology at North Carolina State Univ. and co-author of a paper describing the work. “This work also adds to the body of literature on environmental effects on skull growth.”
The researchers drew on historical data collected by Franz Boas in the late 19th century. Boas collected measurements of the length (front-to-back) and breadth of skulls for many Native American tribes, including hundreds of members of the eastern and western bands of Cherokee.
The researchers analyzed the data, looking only at adults and organizing the adults by year of birth, which ranged from 1783 to 1874. The year of birth, a critical piece of information, provided clues to stressors in an individual’s life. For example, the western band of the Cherokee was subject to the Trail of Tears in 1838, intertribal warfare in the West, disease epidemics and the U.S. Civil War from 1861 to 1865.
The researchers found that head length decreased over time in both bands, for males and females.
In the eastern band, there was a steady decline for males, but a sharp decline for females beginning in the late 1830s—coinciding with the Trail of Tears, when the eastern band fled into the Great Smoky Mountains to avoid forced evacuation to the West.
In the western band, males and females shared a similar pattern of decline: a sharp decline from the late 1820s to the 1850s, followed by a short increase, and then another sharp decline in the early 1860s with the onset of the Civil War.
“When times are tough, people have less access to adequate nutrition and are at greater risk of disease,” Ross says. “This study demonstrates the impact that those difficult times had on the physical growth of the Cherokee people.
“The study also contributes to our understanding of how environmental stressors can influence skull measurements, which has value for helping us understand prehistoric cultures, historic population, and the impact of environmental factors on the health of current populations in the developing world.”
The paper is published online in the Annals of Human Biology.
Source: North Carolina State Univ.
