Bull muskox spar by butting heads, sometimes running at each other full bore before colliding. Four inches of horn and three inches of bone protect the brain from injury during this violent contact. The first time I encountered muskox in the wild I felt as spectacular as Tom Cruise dancing around in his underwear and football helmet in the movie Risky Business. I was skiing across the Arctic National Wildlife Refuge (ANWR) in March as mountains and the coastal plain glowed blue in the winter light. ANWR, long known as the battleground between wilderness and oil lovers, is the sort of place you can slow dance with your inner Frankenstein without the judgement of others. Better yet, it’s one of a handful of regions in Alaska you can see muskox. A herd of 15 grazed on a windswept rise above a frozen river ahead of me. A bull hoofed at…