Where did "a racist bone in [one's] body" and "a mean bone in [one's] body" come from?
Solution 1:
This post is aimed at answering questions 2 and 3.
So far, I haven't found any single adjective that seems to have been clearly the first to be used in the metaphorical expression "a(n) [adjective] bone".
When I say "goes back to __" in the following sections, it obviously means "goes back to at least __". There might be earlier examples that I haven't found.
None of the examples that I've found are from before the 19th century.
"Mean bone" goes back to 1858
There was not a mean hair on his head or a mean bone in his body.
(Lost chapters recovered from the early history of American Methodism, by Joseph Beaumont Wakeley, 1858. p. 239)
"Selfish bone" goes back to 1836
Here is the earliest quote that I've found with "selfish bone":
There was not a selfish bone in the body of one of them.
("The Old Maid's Legacy", by Richard Penn Smith, in Godey's Magazine, Volume 13, July 1836)
There are more examples of "a selfish bone" in books from the 19th century, but it doesn't seem to have been a very frequent expression.
"he hadn't a lazy bone in him" goes back to 1840, and "lazy bone" seems to have been popular between 1860 and 1950
Based on the Google Ngram Viewer, from around 1840-1950, "a lazy bone in" seems to have been more popular than either "a mean bone in" or "a selfish bone in":
The line for "a lazy bone in" shows an isolated blip upward from zero in 1801, but I think that's an error, so I didn't show it.
The earliest use of "a lazy bone in" that I have found so far in Google Books Search is from a book dated to 1840:
Captain T—— was a vigorous, energetic fellow: as sailors say, “he hadn't a lazy bone in him.” He was made of steel and whalebone.
Sven Yargs did further research on this quotation to find out that it comes from the book Two Years Before the Mast, by R. H. Dana, Jr, p. 86. The snippet view in Google Books misattributes this quote to Incidents of Travel in Egypt, Arabia Petræa, and the Holy Land.
This expression is not identical to the term "lazy-bones" as a noun or epithet for a lazy person, but there might be a connection between the two expressions.
Other "adjective bone"s
Here are some other metaphorical expressions of the form "a(n) [adj] bone" that I found:
- a jealous bone
Other "adjective hair"s
The first citation suggests a connection to, or possible development with, an alternative metaphor involving "an [adjective] hair" rather than "an [adjective] bone". Here are early sources I've found with the "hair" expression:
1852 "not a mean hair about him"
Poultry dealer in the Quincy market. Made every cent of his money in the right way, — by diligence, perseverance and economy, — not meanness, for there is not a mean hair about him.
(The Rich Men of Massachusetts, Second Edition, by Abner Forbes, 1852. p. 134)
1858 "not a lazy hair in their heads"
Men are charged with ignorance who have not got a particle; there is not a lazy hair in their heads.
(Emery's Journal of Agriculture, Vol. 2-No. 9., Chicago Ill., Thursday, Aug. 26, 1858, Whole No. 35. Emery & Co.)
1853 "not a lazy hair on his head"
He is incessantly active, both in body and mind; as some people say, he has not a lazy hair on his head.
(letter written by Lizzie Freeman March 1853, published in A Memorial of the Futterleigh Mission and her Martyred Missionaries, by J. Johnston Walsh, 1858, p. 180)
An 1819 source with "mean bone" in a possibly unrelated context
I don't know whether there is any relationship, but I found a source from 1819 that uses "a mean bone" as a literal translation of a Chinese term involving the morpheme 骨 (pinyin gu) 'bone':
Tsëen kŭh tow 賤|頭 [i.e. 賤骨頭] a mean bone, is used in abusive language to denote lowness of birth or conduct.
(A Dictionary of the Chinese Language, by Robert Morrison, p. 486, headword 骨, 6558 "Kŭh or kwŭh, a bone")
According to a comment by Janus Bahs Jacquet, 骨頭 (simplified 骨头) means ‘bone’ and 賤 (simplified 贱) means ‘mean, lowly, base, unworthy, impure’. The Wiktionary entry for 骨頭 says that it can figuratively refer to "character; personal quality". It's possible that the figurative usage of bone evolved separately in Chinese or English; as I said above, I don't know whether there's any connection—I just happened to stumble across this entry while searching Google Books for texts containing the string "a mean bone".
Solution 2:
When doing a Google n-gram search for "racist bone" I came across a reference to a November 1967 issue of Jet magazine. It references a quote from Louise Day Hicks, a Boston politician and staunch opponent of school desegregation. Mrs Hicks and her supporters "insist there ain't a racist bone in her ample Irish body."