Could exogenous genes from another biosphere have aided the evolution of life on Earth's surface over the last half-billion years? That possibility was considered by Thomas Gold in 1992, when he hypothesized that a "deep hot biosphere" (DHB) resides independently well below its cooler surface counterpart. And he suggested that "... in the long term ... there may occasionally be beneficial exchanges of genetic material between microbial life at depth and the surface life." Thus, the question: what evidence is there to support Gold's notion that exogenous genes from the DHB--let us call them "bioplutons"--ever bestowed benefits on the evolution of surface life? In pursuit of this question I drafted a null hypothesis: "Nothing beyond our own biosphere, as we know it today, renders any kind of genetic benefits to biological evolution." After objectively analyzing the evidence and arguments pro and con I failed to reject the null hypothesis, given what we know today, especially the fact that no genetic imprint from the DHB has been identified in eukaryotic genomes. But my conclusion is regarded as tentative, because the fundamentals of Gold's argument, collectively referred to herein as "bioplutonism," might be confirmed eventually with successful probes into the DHB, and with the sampling of its alleged genetic material.