We have no basis to believe that seed exchange networks are an “essential” aspect of traditional indigenous culture. Although we do know that indigenous peoples have used seed exchange networks, this doesn’t imply that those networks are critical parts of indigenous culture.

“The only” is too strong. We have no reason to believe indigenous knowledge of heirloom crops are the one and only possible solution to the eroding genetic base.

Anti-supported. Economic pressure does influence some of them to use nonheirloom varieties.

Supported, because the author believes that our use of “genetically identical” crops makes our food system susceptible to pests and disease. The author believes that developing many varieties of crops can be a way to diversify crop genetics. This is an advantage of using many varieties over a single variety.

Not supported, because we don’t know that geneticists “must” rely on farmers’ knowledge to develop new varieties. Perhaps that knowledge would be very helpful in developing and maintaining new varieties, but that doesn’t imply the knowledge is necessary in order to develop new varieties.