Western values are not winning.
His thesis: Each generation, humans accumulate ~50–60 new mutations. Most are harmless. But some are slightly harmful and aren’t removed. They stack. Over ~3,000 years, humans may have accumulated multiple mutations affecting cognition. In the past, natural selection filtered out harmful traits. Today, modern society buffers survival, meaning that those mutations may persist rather than be removed.
I think that natural selection is active no less than before, and intelligent people do reproduce themselves. Today, that is unclear because of the general mixing that takes place.