生命起源中，一般认为先有RNA，然后再由RNA进化出蛋白质和DNA。这称为RNA世界猜想（The idea that primordial Earth hosted an RNA-only chapter of evolution prior to the emergence of DNA is known as the "RNA world" hypothesis.）
而The Scripps Research Institute (TSRI) 的研究人员提出一种新的猜想，即RNA和DNA同时进化的世界（a world where RNA and DNA evolved simultaneously）。
TSRI Scientists Find Evidence for Alternate Theory of How Life Arose A new study led by scientists at The Scripps Research Institute (TSRI) offers a twist on a popular theory for how life on Earth began about four billion years ago. Ram Krishnamurthy is an associate professor of chemistry at The Scripps Research Institute. The study questions the “RNA world” hypothesis, a theory for how RNA molecules evolved to create proteins and DNA. Instead, the new research offers evidence for a world where RNA and DNA evolved simultaneously. “Even if you believe in a RNA-only world, you have to believe in something that existed with RNA to help it move forward,” said Ramanarayanan Krishnamurthy, associate
