Researchers from Washington State University (WSU) have detected the presence of marigold (Tagetes lucida), a non-tobacco plant substance thought to have some medicinal properties, in ancient Maya drug containers that are more than 1,000 years old. This is the first time scientists have identified a non-tobacco plant in ancient Maya drug containers, and the researchers suggest it may have been used to make tobacco smoking "more enjoyable". 

The discovery of the complete drug containers, 14 small Maya ceramic vessels that also contained traces of two other substances, dried and cured tobacco from the Nicotiana tabacum and N. rustica plants, was made in Mexico's Yucatán peninsula. Published in the journal Scientific Reports, the findings help us further understand ancient Maya drug use practices.

"When you find something really interesting like an intact container it gives you a sense of joy,"  said lead study author, Mario Zimmermann in a press release. "Normally, you are lucky if you find a jade bead. There are literally tons of pottery sherds but complete vessels are scarce and offer a lot of interesting research potential."

Previously, identification of plant substances in Maya artifacts has been limited due to only having a couple of biomarkers to detect substances available, such as caffeine and nicotine. However, the new metabolomics-based analysis developed by WSU can now detect thousands of metabolites (plant compounds) from different substances in residue collected from various archaeological artifacts, like pots and containers, opening up the opportunity to identify new plant substances.  

"While it has been established that tobacco was commonly used throughout the Americas before and after contact, evidence of other plants used for medicinal or religious purposes has remained largely unexplored," Zimmermann said. 

As the two types of tobacco that were identified in the containers were commonly smoked at the time in the region, the additional presence of Mexican marigolds led the researchers to think the Maya purposefully mixed these substances. Marigold has a pungent smell and was thought by the ancient Maya to have some medicinal properties, hence the study hypothesized that the Maya might have mixed these substances for a more enjoyable and rewarding smoking experience. 

This new method of identifying substances will hopefully pave the way for future investigations into the pre-Colombian uses of psychoactive and non-psychoactive plants. "The analysis methods developed in collaboration between the Department of Anthropology and the Institute of Biological Chemistry give us the ability to investigate drug use in the ancient world like never before," Zimmermann said.

"We are expanding frontiers in archaeological science so that we can better investigate the deep time relationships people have had with a wide range of psychoactive plants, which were (and continue to be) consumed by humans all over the world," added co-author Shannon Tushingham. "There are many ingenious ways in which people manage, use, manipulate, and prepare native plants and plant mixtures, and archaeologists are only beginning to scratch the surface of how ancient these practices were."