Rousseau's Isolated Savage

I'm reading Rousseau's Discourse on the Origins of Inequality for the first time in several years (preparing for a Humanities course). It strikes me that his conjectural history of the development of humans has a fatal flaw: the assumption that humans first existed as solitary beings. (And he seems to mean this quite literally; once we can fend for ourselves, mother cuts us loose (dad didn't stick around), and we're off to forage on our own in the vast world.) This seems quite Cartesian and artificial, and I wonder whether anthropology now would simply refute this story. He sees dependence on others as the greatest of evils, but he seems thereby to be reading his own individualism back onto "man in his natural state."

I haven't yet figured out just what this implies for the rest of what he says, but it seems like a serious problem. It seems like one could get at the origins of inequality by looking at the history of the division of labor, without this quaint, and what seems to me implausible story about isolated "man" who needs no others. Thoughts?