I say it "Evolved" from Social Darwinism of the late 1800s because that is the stuff Ayn Rand was jonesing on when she was young and impressionable. Of course to separate himself from charges of being a "Darwinist," Ryan has to distance himself from his hero.
But this ain't an easy task when the internets remember stuff like this at a Ayn Rand Society Shindig:
It turns out that the internets remember lots of stuff about Ryan and Rand. There is so much stuff about Rand being Ryan's role model and other such nonsense, that I think labeling Ryan as an Old Line Social Darwinist is totally fair.
My guess is that this is why Ryan is trying to distance himself from Rand these days. It is because he does not want folks to discover that HE IS A SECRET DARWINIST.