I've read all of Grahams's nonfiction books and feel this was the best. The arguments are completely compelling. There are a couple of things I wonder about, though, so I thought I'd throw them out here.
Concerning the advanced civilization, possibly Atlanteans, who succumbed to the temptation of human women, Graham's ultimate conclusion is that these have to be humans themselves. It is interesting that there offspring were "Giants". It made me think of Ligers, the product of a male lion and a female tiger, which are substantially larger than either lions or tigers, which are of the same Genus but different species. Maternal size/growth genes typically suppressed by paternal genes of the same species are not in this case. Interestingly Ligers are not infertile like some other hybrids. It seems plausible to me that this same phenomenon could have occurred with two closely related Homo species.
I still wonder where the females of the advanced species were. It would be unlike an enlightened culture to send a purely male expeditionary force.
Concerning the advanced civilization, possibly Atlanteans, who succumbed to the temptation of human women, Graham's ultimate conclusion is that these have to be humans themselves. It is interesting that there offspring were "Giants". It made me think of Ligers, the product of a male lion and a female tiger, which are substantially larger than either lions or tigers, which are of the same Genus but different species. Maternal size/growth genes typically suppressed by paternal genes of the same species are not in this case. Interestingly Ligers are not infertile like some other hybrids. It seems plausible to me that this same phenomenon could have occurred with two closely related Homo species.
I still wonder where the females of the advanced species were. It would be unlike an enlightened culture to send a purely male expeditionary force.