“Yet other wild silk worlds to conquer,” the powerful pull of silk
Silk: A World History by Aarathi Prasad (William Morrow, 2024)
Reviewed by Saija Wilson
In Silk: A World History, Aarathi Prasad recounts humankind’s pursuit and use of silk, by focusing on three silk-producing animals and highlighting several individuals who sought to harness the material’s potential. Beginning with silkworms, then giant mollusks, and then spiders, Prasad introduces the species central to researchers’ and silk harvesters’ exploration and experimentation. Taking readers from thousands of years ago, before the silk moth’s complete domestication, to scientific research investigating novel applications for today’s problems, Prasad shows that silk was and is an ingenious substance with endless potential.
Throughout this book, the word “silk” has many meanings. It can refer to the liquid proteins excreted by animals and compressed by glands and spinnerets into strands that solidify upon meeting air or water. At other times, it signifies the product attained by spinning those strands into fine thread and weaving it into lustrous cloth known for its look and even its sound. Prasad declares that silk is above all other fabrics. This is evidenced by its use in trade, in the payment of tributes and bounties, and in sacrificial offerings. Furthermore, over the time period and across the geographies covered in this book, trade routes and cities developed to facilitate the movement of silk, silkworms, and the knowledge of silk cultivation. While early westward trade relied on a passage known as the Silk Road, centuries later, colonial and imperial powers would take to the sea to secure favorable trade agreements and fulfill their need for silk.
The sustained appeal of silk is due to natural characteristics, such as tensile strength, that are passed along from strand to cloth. Casimir Zeglen, a Polish priest, employed these capacities in the late nineteenth century to make and patent a silk bulletproof vest. Zeglen found that when raw silk cloth was woven properly and densely enough, it had “the technical capacity to resist the puncture of a fast-traveling missile” (252-3). Interestingly, Prasad notes that this was not the first time silk was employed as armor. Genghis Khan, who appropriated this knowledge from Chinese warriors, fitted Mongol soldiers with silk shirts to be worn under their armor enhancing its protection. With such applications, silk has called to many across time and space. As a result, the history of silk is one of insatiable and relentless pursuit of profit, whereby all means necessary were employed to conquer nature and bend it to the human will.
Such mastery is exemplified by the complete domestication of the Bombyx mori silkworm. According to Prasad, research indicates that Neolithic Chinese farmers began the process and their descendants finished it between 4,100 and 5,000 years ago. The process of domestication entails selectively breeding wild silk moths based on desired characteristics. By doing so, silk cultivators irrevocably changed the Bombyx mori silkworm and silk moth, creating a “docile” and relatively “immobile” specimen which facilitated silk production (21). Prasad notes that domestication had the unintended effect of making the Bombyx silkworm a perfect subject for scientific study. While natural scientists desired to study them to increase knowledge of the natural world, it is also true that such knowledge had the potential to improve cultivation and therefore increase profits. In this way, sericulture, or silk cultivation, provided not only an impetus for the scientific study of Bombyx but also the means.
In the introduction to Silk, Prasad discusses her own encounter with Bombyx silkworms describing their “plump and round” bodies, and watching them increase in size through nearly constant feeding (2). She expresses wonder at watching them stop eating and begin wrapping themselves in silk, later finding them entirely hidden by their cocoons. Prasad notes that a seventeenth-century anatomist dissected them at this stage and shared what he found, shocking scientific societies. Acknowledging that she could not have done the same, Prasad provides an opportunity for readers to consider the complexity of cute wriggling creatures meeting their calculated fate.
The realities of complete domestication and some cultivation practices provide further opportunities for readers to grapple with the results of sericulture beyond silk production. Domestication has ensured Bombyx is completely reliant on cultivators and cannot survive in the wild. Reasons for this include the loss of many mechanisms for self-preservation, including camouflaging behaviors and methods for seeking out food, and its ability to see and fly. Furthermore, some cultivation practices seek to improve efficiency and profitability at Bombyx’s expense. In the wild, after emerging, silk moths subsist on the mulberry leaves it consumes as a silkworm, mate and die. In captivity, however, the process of emerging from its cocoon may be interrupted. When a silk moth breaks free following metamorphosis, it damages the silk composing its cocoon. In an effort to prevent this, some silk cultivators boil the cocoons, killing the moths, and loosening the strands of silk without rupturing them.
In this way, though sericulture developed centuries before European colonialism and imperialism, its regimented processes for accounting for every part of the silkworm’s life and relentlessly increasing output match those systems. This is supported by colonial and imperial efforts to locate and domesticate other silk producers with hopes of supplanting Bombyx. The work of Sir Thomas Wardle furthered such missions. Wardle, an English silk dyer, was knighted for his success in getting wild Tussar silk to take up color like that of Bombyx. When speaking of the 1866 Colonial and Indian Exhibition in South Kensington, London, Wardle recognized the importance of his work to the empire, and therefore of colonialism and imperialism. In quotes including the one in this review’s title, Wardle asserts that there are “‘yet other wild silk worlds to conquer’” (140). Here, “conquer” signifies the work of civilizing wild silk enabling it to behave as profitable types do. In doing this work, Wardle and others sought to justify incursions into territories that did not belong to them. Wardle observed that “‘our own small and comparatively insignificant island has little room for expansion, except in these broad lands across the sea we have made our own’” (136).
Within colonial and imperial systems, the acquisition of scientific knowledge is often justified by economic incentive (even if delayed). Prasad illustrates this principle in her discussion of individuals who could only pursue their passions for science by either working irrelevant jobs to fund their goals or by convincing government officials that their studies could eventually yield profit. Such rationalizations included finding alternatives to Bombyx for producing silk at scale. While searching for these specimens, researchers and explorers relied on the knowledge and expertise of Indigenous and enslaved Black people. These people often helped locate specimens and may have also demonstrated how to handle and harvest silk. Their knowledge was shared with and recorded by researchers, contributing to growing domains of information in which there would be no record of their presence.
Prasad acknowledges the difficulty of finding the voices of the majority of people involved in silk’s history. For this reason, individuals like the Indigenous and enslaved Black guides are often left out of histories all together. However, knowing more about these people would enrich the stories we tell about silk while being in line with efforts to write history about those on the margins of dominant classes. Silk is an extremely ambitious book seeking to connect many seemingly disparate threads. As such, it provides an opportunity for other researchers to build on her work and perhaps find more about those who seem unknowable. For this reason, readers would have benefited from a more robust method of citation including footnotes and a works cited section.
This book particularly shines when Prasad delves into the biology of silk-producing animals and the processes required to make silk. As a biologist, she utilizes her expertise to explain complex processes of evolution, relate it to advancements in natural history, and highlight relevant and interesting information. Through her discussion of the evolutionary developments that have shaped silk-producing animals’ physiology, readers gain a deeper understanding of how each animal’s biology and behaviors support its life.
The final section of the book is devoted to detailing research of novel applications for silk, along with the foundational observations and experiments that undergird these efforts. She shows that by employing evermore powerful tools, scientists have been able to discover the nature of silk’s tensile strength and explain why past uses were successful. Additionally, well-established medicinal usages, like using silk thread for sutures, and knowledge of silk’s antiviral nature that protect metamorphosing caterpillars from external diseases, encouraged further research into its medical capabilities. Prasad discusses potential uses of silk to create implants that can recreate tendons, ligaments, and cartilage inside the human body. These applications would be particularly useful because silk implants would biodegrade after their purpose was served, and require no secondary surgery to remove them. However, like all scientific experiments aimed at improving medical treatment, new uses of silk need to undergo extensive trials.
An additional issue that plagues silk innovations is that of supply at scale. From clothing to medical implants to tools for the military, acquiring necessary amounts of silk seems an insurmountable obstacle. Some efforts to optimize silk harvesting were quite disturbing. One such instance included the modification of mammary cells in goats to include spider silk genes, allowing silk proteins to be excreted into goats’ milk and filtered out. Ultimately, this experiment was unsuccessful and has resulted in genetically modified goats “being phased out as furry factories for spider silk” (261). Another instance involved the creation of a machine that forces restrained spiders to produce silk, a nineteenth-century and more recent innovation. The discussions of forcing spiders to produce silk were particularly difficult to read, especially since one instance is preceded by descriptions of spider anatomy that highlights their vitality and complexity. Here again, the reader is confronted with cruel harvesting practices juxtaposed with human need for silk.
One project that has seen significant developments in harvesting silk from silkworms without harming silk moths is a project called Silk Pavilion at Massachusetts Institute of Technology (MIT). This project shows that when we accept claims that the production of silk is sustainable despite knowing that in many cases it involves the boiling of ensconced silk moths, we miss opportunities for further ingenuity. Prasad has shown that if silk is to be what so many hope for, the effects beyond humankind must be a priority. MIT’s effort, led by Professor Neri Oxman, is an ingenious innovation supported by Oxman’s belief that “We must reorient ourselves with the natural environment, or else perish” (279). It appears that a better future for silk-producers and innovations with silk may rely on efforts like Oxman’s.
Overall, Silk presents an accessible entry point into both the historical and biological aspects of the story of silk. As such, it is a great book for general audiences who may be new to natural history. Prasad’s discussions of biological facts are extremely interesting and highlight her passion for her field. By exploring evolutionary history and developments in the natural sciences, Prasad presents important details and milestones that help readers understand why silkworms, marine mollusks, and arachnids look and behave the way they do, while enabling readers to understand scientific inquiries being pursued today. While accomplishing this, Prasad has widened the traditional scope of histories of silk and provided many avenues for further research.
Saija Wilson has studied history and library science with a focus on archives. Right now she helps make special collections materials available online.
