A Harbor Frozen in Time
Between 2004 and 2013, construction for a new subterranean rail line in Istanbul's Yenikapı neighborhood turned into one of the world's largest archaeological digs. Engineers unearthed the lost Theodosian Harbor, a major commercial port of Byzantine Constantinople built during the reign of Emperor Theodosius I (379-395 CE). The waterlogged, anaerobic sediments of the silted-up harbor preserved an incredible array of organic materials. Over an area of 58,000 square meters, archaeologists discovered 37 shipwrecks dating from the 5th to the 11th centuries. These ships, along with countless amphorae, ropes, leather goods, and other artifacts, show commerce and daily life at the western end of the Silk Road.
Reading the Molecular Past
Among the finds were residues of silk, the most valuable commodity of the Byzantine economy. For centuries, the empire imported raw silk from China to be woven in imperial factories. Around 552 CE, monks famously smuggled silkworm eggs of the domesticated species Bombyx mori into the empire, breaking the Chinese monopoly and establishing a local industry. Modern analytical techniques, however, are showing more complexity.
Scientists use molecular archaeology on these fragile remnants. Using a technique called DNA barcoding, they can identify the exact species of moth that produced a given silk fiber. This method often targets a specific mitochondrial gene, cytochrome c oxidase I (COI), which differs from species to species. Analysis of fibers from sites like this can distinguish between the domesticated silk of Bombyx mori and various species of wild silk moths, such as those from the Antheraea or Samia genera. The presence of wild silks, which have different properties, shows diverse and possibly older trade networks than the state-controlled production of domesticated silk. The science goes a step further by analyzing trace DNA from the mulberry leaves the silkworms consumed, which can potentially pinpoint the geographic region in China where the silk originated.