mystery of beards

The 7/28 New Yorker has a review of a book, Whiskerology: The Culture of Hair in 19th Century America by Sarah Gold McBride, that has not one but two insufficient explanations for the question I've only previously seen entirely different insufficient explanations for, namely what was the cause of the Wave of Beards that settled on the faces of most middle-to-upper-class European and American men in the mid 19th century?

McBride's first explanation is that it was an attempt to show white male virility in the face of the rise of the supposedly emasculating suffragist movement. Besides being inane (as noted by the reviewer, Margaret Talbot: "Did men really need beards to remind anyone that they were in charge?"), this explanation doesn't fit chronologically, as the suffragist movement was an odd minor cause at the time the Wave of Beards began. It became a major public movement at the time that the beards were going away.

McBride's second explanation is white men fearing African American barbers with straight razors. Whatever you might think of that as an explanation in the US (I place it in the "inane" category), it wouldn't apply in Europe, yet the Wave of Beards settled on faces there too.

I noticed an error which I'm not sure if it is McBride's or Talbot's. Talbot writes that "J.D. Vance is the first Vice-President since the nineteenth century to wear a beard while in office." That's not quite true. While there were 5 Presidents with beards in the olden days, there were only 2 such Vice-Presidents: Schuyler Colfax (1869-1873) and Charles W. Fairbanks (1905-1909). So, not quite 19th century.