"The best explanation for this is that they came directly from Africa," said Kistler. "However, we wanted to test the possibility that gourds did float from Africa to form New World populations."
Previous studies found that gourds do float in the oceans and that after long periods of time in the ocean they still have viable seeds. The researchers developed an ocean-current drift model that showed that wild African gourds could have simply floated across the Atlantic during the Late Pleistocene. They suggest that large mammals like the mammoth helped naturalized populations establish in the neotropics, because these large mammals were known to eat various members of the family that includes gourds. The seeds are found in ancient deposits of large mammal dung.
Bottle gourds in Africa exist today mostly in the domesticated form, with only small populations of the wild variety in Kenya and Zimbabwe. In the ocean drift model, the researchers looked at realistic, unrealistically conservative and optimistic scenarios. They divided the western coast of Africa by latitude and simulated 12 years of gourd release where one gourd per month entered the ocean in each latitude division. The shortest amount of time it took for a gourd to arrive was 100 days, with an average arrival time of about nine months.
According to the researchers, it is feasible that gourds did float across the Atlantic Ocean frequently. This is especially true of gourds growing near rivers that flow into the ocean.
"It wasn't one gourd that came over and gave rise to all New World gourds," said Kistler. "Populations show up in Florida and Mexico around 10,000 years ago and in Central America a little later."
|Contact: A'ndrea Elyse Messer|