The mystery of the bottle gourd – namely that this African or Eurasian species was being grown in the Americas over 8,000 years ago – comes from the difficulty in understanding how it arrived in the Americas. The bottle gourd is usually thought to have drifted across the Atlantic Ocean from Africa to South America, but in 2005 a group of researchers suggested that it may have been domesticated earlier than food crops and livestock and, like dogs, was brought into the New World at the end of the ice age by the native hunter-gatherer Paleo-Indians, which they based on a study of the genetics of archaeological samples. This study purportedly showed that gourds in American archaeological finds were more closely related to Asian variants than to African ones.