Not to beat an old horse to death, but I have heard and read on good authority -- here too, I think -- that the older and larger the tea leaf, the less caffeine present. It was logically suggested that it make sense that the tender shoots be most full of poison to ward off those who eat tender shoots. Incidentally and parenthetically, that's why we monkeys are in the habit of eating but a little bit of leaf from every tree we encounter so that, should we be poisoned, we'll get a relatively small dose.
Now, are there any legitimate emperical studies available on this? (I speak of the bit about the leaf age/size to caffeine correlation; not to the monkey thing.)
Michael