Hella-Smelly Yellow-Pee

Last Wednesday night, I had some people over for steaks, sided with some beautifully seared asparagus (thank you, thank you). This sprouted a conversation on the wonders of this vegetable -- after all, a scene of Austin Powers in Goldmember really spears the point. Questions begged.

Why does it make our pee smell?
Why does it make our pee so yellow?
Can this be used as some kind of territory-marking liquid around our homes, like wolves do in the wilderness?

I went to ask Greenworks to get the straight dope on this local harvest, and understand generally how stuff works with asparagus. Here's a 15-second summary.

Asparagus has six sulfur-containing compounds in it. The smell is caused by S-Methyl Thioesters, which are compounds that result from the reaction of an acid with one of those sulfur-containing alcohols. But not everyone gets it: about 40% notice the smell, and the rest don't. Why? The jury's still out. Some think the 40% have an enzyme that lets us to break down the sulfurous amino acids to produce the smellier components, while others believe those 40% have a gene that gives the ability to smell those odours. (I personally believe the former reasoning, though this should be easy to sort out by experiment: just have them smell each other's pee.)

Either way, it's a small price (for others) to pay for such a delicious vegetable (for you). And aside from the pee smell, it has very good nutritional value and taste. (I mean the asparagus, not the asparagus urine.)