We're getting behind so will try here to catch up.

Today's Moment of Science has to do with caribou and reindeer.  Reindeer are either a  sub-species of caribou or an extremely close cousin, take your pick.  Scientists, using gene mapping, still don't quite agree on that.

The reindeer, in any case, are smaller and stockier and much less nomadic. They were domesticated many centuries ago by a group of Scandinavian indigenous people called Sami, also known as Laplanders. The Sami used them both for meat and to pull sleds.

Sometime between then and now, a mysterious philanthropist named St. Nikolai taught some of them to fly, a landmark moment in the shipping business.

Today, in Alaska, there are several herds of wild caribou who migrate huge distance as they forage for plant food. And their is, apparently, a pretty successful reindeer farming industry.

Caribou and reindeer are unique in another interesting way. They are the only "ungulates" -- that is, hoofed mammals -- in which both males and females both grow antlers. You might say they are ALL transgendered.

Okay, one more thing: antlers vs. horns.  Antlers are shed every fall and begun anew every spring. Famous antler growers include caribou, elk, and deer. Horns, on the other hand, are never shed, but keep growing bigger.  Horn growers include bighorn sheep, mountain goats, and bison.