Poly.Sci.187, later retitled Mansbestfriend 4: Poly.Sci.187, is an instrumental studio album by American hip hop artist Sole. It was released on Anticon in 2007.
Sole adopted the "Mansbestfriend" moniker for this album (as he had first done for The New Human Is Illegal, a revised version of Mansbestfriend Pt. 2: No Thanks). He intended to release instrumental work under that name. However, "Mansbestfriend" has since reverted to the title of a series of self-produced albums (as it began) with the release of fifth and sixth entries in the series in 2011. Poly.Sci.187 thereby retroactively became Mansbestfriend 4.
Marisa Brown of AllMusic gave the album 2.5 stars out of 5, calling it "a dismal, electronic-leaning set that moves around sloshily without much heed for reason or direction." David Ma of XLR8R said, "Sole is surely a creative artist, but Poly.Sci.187 is an unremarkable footnote in his otherwise strong discography."