Level of nutritional knowledge: I'm finishing up an internship in clinical nutrition.
How did I get to paleo? Well, I already disliked the USDA-type diet from casual research I had done before going back to school for nutrition - I was into lifting and fitness generally, and there tends to be a strong bias against the low-protein, high-carb approach. I was frustrated with the idea of low-carb, because even though it made sense to me, I didn't like the idea of pounding CAFO meat and cheese indiscriminately, and I couldn't get over the aversion to fruit and many tubers, or the abuse of carb-free and low-carb frankenfoods. I was starting around that time to warm up to eating locally and sustainably, having rising sentiments regarding the cornucopia of problems with industrial farm-produced food (my husband was getting more into homebrewing, too, which tends to have a local, independent vibe). When I came across paleo, it appealed to me logically, scientifically, and emotionally. I remember it triggering some thought back to an honors anthropology course I had taken that touched on the diet of early man. It just...made sense, on multiple levels.
That's such a reductive version of how it happened, but I suppose those are the highlights, as best as I can discern.
As a side note, out of all of my peers (who are almost all USDA acolytes), the one who accepts my position on diet and nutrition the most fully is our group's localvore vegan (the sort who favors real food over sugar-laden-but-vegan-so-they're-healthy concoctions). The others insist my avoidance of grains is unhealthy. I try to pay him the same respect. Strange bedfellows.