Parents meditate, grow parts of their brains, and pass on the improvements to their children? Sounds like Lamarckism to me.
I think the author means that rituals involving meditation and trance gave rise to enhanced memory skills, which, in turn, altered the routines of early man in a way that made the use of the ability to understand symbols. Once such behavior became established, however it did, those offspring that excelled in symbol recognition were favored by natural selection.
Yes. Lysenko lives!