According to an article published in 1996 by Ihaka and Gentleman:
“The work has been heavily influenced by two existing
languages-Becker, Chambers, and Wilks' S (1985) and Steel and Sussman's Scheme (1975). We felt that there were strong points in each of these languages and that it would
be interesting to see if the strengths could be combined. The resulting language is very similar in appearance to S, but the underlying implementation and semantics are derived
from Scheme. In fact, we implemented the language by first writing an interpreter for a Scheme subset and then progressively mutating it to resemble S.”
“The work has been heavily influenced by two existing languages-Becker, Chambers, and Wilks' S (1985) and Steel and Sussman's Scheme (1975). We felt that there were strong points in each of these languages and that it would be interesting to see if the strengths could be combined. The resulting language is very similar in appearance to S, but the underlying implementation and semantics are derived from Scheme. In fact, we implemented the language by first writing an interpreter for a Scheme subset and then progressively mutating it to resemble S.”
(https://www.stat.auckland.ac.nz/~ihaka/downloads/R-paper.pdf)
Unfortunately R’s gain was LispStat’s loss: https://www.jstatsoft.org/issue/view/v013