Picture the caves of Lascaux over 40,000 years ago. Those prehistoric artists painted their pictures of horses, stags, bulls and bison using only the light from stone lamps burning animal fat. Writer JANE BROX starts her new book, Brilliant: The Evolution of Artificial Light, in those ancient caves where the remnants of early human fires can still be found. And for thousands of years, lighting hardly changed. But with the inventions of gaslight and the incandescent light bulb, human culture altered in profound ways. Marty talks with writer JANE BROX about the history of light. And, University of California –Davis professor MICHAEL SIMINOVITCH explains the lighting of today and tomorrow — incandescents, compact fluorescents or LEDs?