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Cockroach egg impressions from 4,300 years ago

More information about early human settlements – and in this case the insects who lived alongside them – is being found in ancient bits of broken pottery.

Pottery pieces that had cockroach egg impressions. Image credit: Prof. Hiroki Obata

Pottery pieces with cockroach egg impressions. Image via Prof. Hiroki Obata

Cockroaches were as much a nuisance 4,300 years ago as they are today, according to archaeological findings in Japan. Archaeologists from the Kumamoto University in Japan have discovered impressions left by cockroach egg cases on pieces of pottery that date that far back. The size and shape of the egg cases indicate they came from the smokybrown cockroach, a species native to southern China. This new discovery indicates, along other things, that the smokybrown cockroach was scurrying around Japan about 3,700 to 4,000 years earlier than thought.

Ancient pottery reveals much about ancient societies. Clay vessels that hold remnants of food and other items preserved through time provide a glimpse into the lives of people who lived long ago. But it wasn’t till fairly recently that scientists realized that indentations on the surface, and holes inside earthernware also told stories about the past.

Smokybrown cockroach, Periplaneta fuliginosa. Image credit: Toby Hudson via Wikimedia Commons.

Smokybrown cockroach, Periplaneta fuliginosa. Image credit: Toby Hudson via Wikimedia Commons.

Professor Hiroki Obata, an archaeologist at Kumamoto University, Japan, said in a statement:

Countless vacant holes on the surface of potsherds [broken pottery pieces] had been all but ignored until about 25 years ago. Since then, however, the meaning and importance of these holes has become well understood. They can be the impression of seeds, nuts, insects or shells.

Small objects can get mixed into clay that’s used to create pottery. If the objects are organic, for example seeds, these substances will deteriorate over time to leave an impression on the surface, or a cavity inside the pottery.

Such seed impressions are valuable clues to the state of ancient agriculture.

In one instance, Professor Obata and his team used x-rays, CT imaging and scanning electron microscopy to obtain detailed images of pottery shards from an ancient rubbish heap, used from the years 5,300 to 3,500 B.C. Among over 500 impressions, 66 were matched to the seed of a perennial herb, Perilla frutescens var. frutescens. This seed is still used today to make perilla oil, a medicinal and culinary ingredient.

In their latest study, Professor Obata and his team looked at two pieces of pottery from the Motonobaru archeological site that dates to the late Jomon Period of Japan (2,500 – 1,300 BC). One piece was found to be about 4,000 years old, and the other, about 4,300 years.

They used a method called impression replica to obtain silica casts of the pottery surface. In other words, silica is used to fill the cavities on the surface to obtain the shapes of objects that created the cavities. The team then took highly detailed images of the casts using a scanning electron microscope.

The images revealed the presence of an all too familiar pest, cockroaches. On the pottery surfaces were impressions of cockroach egg cases. The cases, measuring 11 millimeters (0.43 inches) across, were identified as those of the smokybrown cockroach, Periplaneta fuliginosa. This species, native to southern China, had been known from 18th century Japanese art and literature. (Earlier cockroach art depictions are believed to be a domestic cockroach species.)

Scanning electron microscope image of a cockroach egg case silicone cast. Image credit: Prof. Hiroki Obata

Scanning electron microscope image of a cockroach egg case silicone cast. Image credit: Prof. Hiroki Obata

A year ago, Professor Obata and his colleagues had also found evidence of another pest from the same archaeological site. They discovered 173 pottery impressions indicating the presence of maize weevils. Said Professor Obata, in the same statement:

The maize weevil is a type of harmful insect that eats stored starch food materials such as acorns or chestnuts, which are known to be typical stored food for that period in Japan.

The existence of many maize weevils and cockroaches shows that these ancient humans lived settled lifestyles. With this latest research, we have revealed that there were cockroaches in human living areas from a period older than was previously believed.

More and more information about ancient human life is being found from potsherds [broken pottery pieces]. Soft and small items have some difficulty remaining in the soil for a significant amount of time, but they can be kept safe within these pottery fragments. Like little time capsules, potsherds are packed full of treasures which help to reveal the story about the living conditions of ancient humans.

Scanning electron microscope image of a maize weevil silicone replica. Image credit: Prof. Hiroki Obata

Scanning electron microscope image of a maize weevil silicone replica. Image via Prof. Hiroki Obata

Bottom line: Archaeologists at Kumamoto University in Japan found impressions left by cockroach egg cases on the surface of pottery shards dating as far back as 4,300 years. Based on the size and shape of the egg cases, the eggs appear to be from the smokybrown cockroach, a species native to southern China.

Shireen Gonzaga

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