Day 072 - Evolution machines

Submitted by Sam on 31 July, 2011 - 22:30

Neo-evolution is factorially faster than normal evolutionary processes. Our genetically engineered organisms have already neo-evolved – shortcutting traditional evolution to produce desirable results without the costly time-delay of selection over hundreds or thousands of generations. Higher-yielding and insecticide-resistant crops have been engineered through the painstaking modification of individual genes, achieving better results than years of selective breeding in a fraction of the time. Genetic engineering of humans, both embryonic and those already alive, will perhaps one day bring the benefits of this new type of evolution to our bodies.

At the moment, we simply do not understand how DNA sequences encode useful functions, and so genetic engineering remains a tremendously costly and laborious process. It cost $25 million and took 150 person-years to engineer just a dozen genes in yeast to cause it to produce an antimalarial drug, and commercial production has yet to begin. The amount of time and money required to effect a beneficial result through genetic engineering – even if it involves relatively simple changes to only a dozen genes – is so costly that the transformative idea of neo-evolved humans has been kept at a safe distance.

But there are other ways to neo-evolve that might make the possibility of too-good-to-miss genetic enhancements in humans a reality before long. Earlier this year, for instance, the National Academy of Engineering awarded its Draper Prize to Francis Arnold and Willem Stemmer for their independent work towards 'directed evolution', a technique which harnesses the power of traditional evolution in a highly optimized environment to accelerate the evolution of desirable proteins with properties not found in nature. Rather than attempt to manually code the strings of individual DNA letters necessary to effect a particular trait, directed evolution and its associated 'evolution machines' take a prototype 'parent' gene, create a library of genetic variants from it and apply selection pressures to screen for the strains that produce the desired trait, iterating this process with the best of each batch until the strongest remain. This was first evidenced in 2009, when geneticist Harris Wang used directed evolution to create new proteins in E. coli bacteria that would produce more of the pigment that makes tomatoes red than was previously possible.

To achieve this genetic modification without manually fine-tuning each gene, Wang synthesized 50,000 DNA strands which contained modified sequences of genes that produce the pigment, and multiplied them in his evolution machine. After repeating the process 35 times with the results of each cycle fed into the next, he produced some 15 billion new strains, each with a different combination of mutations in the target pigment-producing genes. Of these new strains, some produced up to five times as much pigment as the original strain, more than the entire biosynthesis industry had ever achieved. The process took days rather than years.

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