February 11, 2014
Has The Mystery Of New World Bottle Gourds Finally Been Solved?
Brett Smith for redOrbit.com - Your Universe Online
Known to early Native Americans as a canteen or storage container, the bottle gourd was once considered an essential accessory. Since wild versions of the gourd don’t grow in the Americas, scientists have long wondered how it originated in the New World.A new study published in the Proceedings of the National Academies of Science (PNAS) has found an answer: it floated across the ocean from Africa.
"The bottle gourd's always been an anomaly. It's been puzzling people for a long time," study author Bruce Smith, an expert in American plant domestication at the Smithsonian Institution's National Museum of Natural History told USA Today's Traci Watson.
“The bottle gourd is no longer an anomaly,” he asserted.
Also referred to as the calabash, opo squash or long melon, Lagenaria sicenaria was one of the first domesticated plants, used by humans as far back as 11,000 years ago. A study published in PNAS in 2005 found that the bottle gourd came to the Americas with Asians as they migrated across the Bering land bridge. However, anthropologists have yet to find significant evidence of the bottle gourd's widespread use among Asian or Alaskan inhabitants of that time.
In the latest study, the study team gathered modern gourds from across the Americas, as well as nine archival samples of gourds that dated back as far as 10,000 years. The researchers examined the DNA of these American gourds with those of domestic gourds grown in Africa and gourds collected from two of the last remaining sites in Africa where they grow wild.
The scientists discovered that the genomes of the African and Eurasian gourds are quite dissimilar to each other, having split thousands of years ago. However, the modern American gourds, and the gourds uncovered in ancient American settlements all had the genetic imprint of gourds from Africa.
The scientists also used data sets on historical ocean currents to establish the rate at which floating objects can drift. Since domestic bottle gourds under these theoretical conditions remain viable for up to one year, the team looked for proof that a gourd could make the crossing from Africa to the Americas within that time span.
Taken together, the two analyses led the study team to conclude that bottle gourds had indeed traveled from Africa to the New World by way of Atlantic Ocean currents.
Botanist Hanno Schaefer of Germany's Technical University of Munich told USA Today he was skeptical of the results since the researchers didn’t include any bottle gourds from Asia.
"I do now believe bottle gourds didn't come with Asian colonizers," Schaefer said. "But I still think that what they have is not enough to tell us what happened."
Study author Logan Kistler noted that his team wants to get more data from ancient Asian gourds. Even after his study’s conclusion – Kistler still called the gourd “enigmatic.”
"(The bottle gourd is) so widespread so early on, and it's used so cross-culturally," said Kistler, a molecular anthropologist at Pennsylvania State University. "We have much more to learn about this species."