Pumpkins were almost extinct once. They survive only thanks to our love for sweet pumpkin dishes.
About 10 000 years ago, the pumpkins were almost extinct, according to the researchers from University of Oklahoma (http://www.pnas.org/content/early/2015/11/11/1516109112). The main reason for this was the disappearance of big herbivores (plant-eaters) that were necessary for the plants to spread their seeds. As authors describe it, the pumpkins survived thanks to the development of the symbiosis between the plants and the humans. This means that humans gained a new source of food while pumpkins could survive thanks to the domestication.
The researchers reached their conclusion after examining genetic sequence of 19 extinct and 72 modern pumpkins. Based on the changes in frequencies of the genes, the scientists could see that humans started to cultivate pumpkins about 10 000 years ago. Those first farmers were interested in growing pumpkins with sweeter taste as first wild pumpkins were bitter. As a result, genes responsible for the sweeter taste of the pumpkins became more common.
At the same time as humans started cultivating pumpkins, the genetic variability in wild pumpkins decreased dramatically showing that the numbers and variety of wild pumpkins decreased. The main cause of this was the extinction of big mammals, such as mammoths, because this had put a stop to the way pumpkin seeds were spread.
Because of the preference of the farmers, the pumpkins became bigger and sweeter, and their skin became thinner with time. That is how the pumpkins we know today were created.