Word count: 77
Average length: 5.30
Difficulty: a soft 5
The seed for this one was 41 Across, which is a fascinating concept and reinforces that we are all one big family (and should act accordingly). More on that below. This entry also required a slightly over-sized grid (16×15). Enjoy, and if you do, please share expansively.
Picture is apropos of nothing in the puzzle but today is a special day (only 2 years til Medicare!). Actually, it kind of relates to 26A.
18A: my third favorite CSN song after Guinevere and Helplessly Hoping. I love the propulsive beat and engaging travelogue.
41A: In the words of Wikipedia, this answer is “the matrilineal most recent common ancestor (MRCA) of all living humans. In other words, she is defined as the most recent woman from whom all living humans descend in an unbroken line purely through their mothers and through the mothers of those mothers, back until all lines converge on one woman.” The concept is unrelated to the biblical woman of the same name; there were probably thousands of other women alive at the time that this answer lived (roughly 150,000 years ago), but none of them left descendants whose descendants are living today. To me, this is an incredibly powerful concept, which underlines that however different we look, feel, or act, and whatever we hold dear, every one of the more than 7 billion humans alive today is a cousin of some degree to every other human. If that’s not mind-blowing enough, check out Last Universal Common Ancestor.
64A: These are wonderful books. The follow-on trilogy, two books in, is just as good so far. I haven’t seen The Golden Compass, which was based on book 1 of the answer, but I understand it pulls some punches compared to the book.
32D and 60D: Apologies if these names are unfamiliar to younger solvers (“younger” is an increasingly expansive category, currently encompassing 80% of the U.S. population compared to yours truly), but I think they’re prominent enough to be fair game for a crossword.