DHT is a potent agonist of the AR, and is in fact the most potent known endogenous ligand of the receptor. It has an affinity (K d ) of to nM for the human AR, which is about 2- to 3-fold higher than that of testosterone (K d = to nM)  and 15–30 times higher than that of adrenal androgens .  In addition, the dissociation rate of DHT from the AR is 5-fold slower than that of testosterone.  The EC 50 of DHT for activation of the AR is nM, which is about 5-fold stronger than that of testosterone (EC 50 = nM).  In bioassays , DHT has been found to be - to 10-fold more potent than testosterone. 
Hey Richard – curious about your thoughts on carbs driving down testosterone. Do you have any studies to that end? I wonder whether the Kitavans had/have low testosterone, despite 70% carb intake? It doesn’t seem immediately obvious to me that carb intake alone would inhibit testosterone, as long as you were getting adequate cholesterol, fat-soluble vitamins, zinc, selenium, etc. to support testosterone levels. These nutrients are often severely lacking in modern diets, as I’m sure you know! So it seems like misplacing causation for correlation to say that modern diets lower testosterone BECAUSE of their high carb levels. (They also have low mineral density, low fat-soluble vitamin levels, low fiber, low polyphenols/antioxidants, high iron, high fluoride/bromide, etc., which all could be confounding factors in the carbs-lower-testosterone hypothesis.)
Nice article. I’m convinced that Boron, is an essential nutrient(and here in the states we have one of the lowest intakes of it), They’ve found so many ways that its beneficial(hormone, bone, joint….) for health) and almost no negative effects until absurd amounts are given. Boric acid is used in automotive oil as a colloid. It has the unusual property that the higher the pressure the more it lubricates. I think it may do the same in humans(it is concentrated in joint fluid). I had shoulder joint pain that prevented me from benching-3 days of 30mg/day boron eliminated it. Also note that boron is highly concentrated in the heart and testes.