The evolutionary approach to building functional molecules is adaptable. Whether we are talking about an RNA molecule in the primordial soup evolving the ability to copy itself or a researcher in a lab evolving RNA to bind to tumor cells, the basic process is the same: variation, selection, reproduction, and repetition.

The potential applications of this approach are stunning. Andy’s lab is working on RNA molecules that:

• bind the chemical warfare agent ricin to alert us to a terrorist attack
• act as decoys for HIV proteins and sabotage the virus’s efforts to replicate
• bind to tumor cells to detect cancer
• deliver chemotherapy directly to cancerous cells

And that’s just one research group. Biotechnology researchers around the world are now using directed evolution to engineer molecules for all sorts of purposes. “The cool thing is that this is all still based on directed evolution,” says Andy.

Andy Ellington’s scientific career did not begin in the field of biotechnology; instead, he set off to learn more about how life first evolved — but this research pushed him towards the practical applications of biotechnology. The two areas of research, it turns out, ask the same question: how can we evolve molecules that do particular jobs? As he says of the students who are now using evolution to generate new medicines and diagnostics: “For many of them, their first love was origins research — and only later on did they become interested in biotech. However, without their fundamental appreciation of molecular evolution and origins, they would not have had the necessary understanding to evolve anti-virals or cancer therapeutics. It isn’t just knowing that molecular evolution can and does happen in a test tube; it’s an understanding of how large adaptations in molecular function, which occurred at the origin of life, can potentially be recapitulated today.”

Discussion and extension questions:

1. What three characteristics does a system need in order for natural or artificial selection to work on it? Explain how Andy’s RNA molecules exhibit each of these characteristics. Explain how a wild population of fruit flies might exhibit each of these characteristics.
2. Research another real-life example of (intentional or unintentional) artificial selection. Describe what happened in that situation and the consequences of the evolution.
3. What are the similarities and differences between the evolution of useful molecules at the origin of life and the evolution of useful molecules in Andy’s lab?
4. How does the discovery that some RNA molecules are able to catalyze chemical reactions relate to the origin of life?
5. What are some advantages of using evolution to engineer useful molecules? What are some advantages of using design to engineer useful molecules?