yytz: Through learning Torah we can fulfill many other mitzvos in the way of “unishalma parim sfaseinu”. Also, see shaar daled in Nefesh HaChaim. An engineer may save someone’s life after he’s already in danger. Learning Torah can prevent the danger altogether. Also, the sefer Binyan Olam explains that although a person is obligated to stop learning Torah to perform a mitvah sh’i efshi al yedei acheirim (such as saving someone’s life), it would be comparable to buying a lotto to a $50 million dollar lotto but only winning $45 million (my words). It’s still a great mitzvah but its not limud HaTorah.
zahavasdad: It looks like I wasn’t clear. Yes you may need to know some zoology/biology for something like chulin. But my point was that until you are going to learn chulin, you don’t need to know it.
I learned chemistry in high school, I don’t know what the chemical composition of paint thinner is, but I would still be wary of using it to burn something. Those boys acted stupidly, and knowing the chemical formula to glucose would not have changed that.
Unless you are going to write English books on Torah or work in Kiruv, you don’t need to be able to relate Torah to the people who need that.
Again, my point is that the value of these subjects are relative to the person’s actual need of them. When the need arises, the value is high. Before then, they have no value. Like buying a lulav before Pesach.