You hear lots of talk in wine country about the way careful vineyard managers and winemakers baby their delicate grapes. But not all the grapes. Muscat, for instance, can be so rubbery that you could jump on them and they wouldn’t pop. In truth, the grapes might not be quite that sturdy, but that may be one reason why muscat is thought to be one of the world’s oldest grape varieties. It takes some toughness to hang around for millennia.