Acquired Traits Can Be Inherited via Small RNAs

From CUMC News:

Columbia University Medical Center (CUMC) researchers have found the first direct evidence that an acquired trait can be inherited without any DNA involvement. The findings suggest that Lamarck, whose theory of evolution was eclipsed by Darwin’s, may not have been entirely wrong. The study is slated to appear in the December 9 issue of Cell. “In our study, roundworms that developed resistance to a virus were able to pass along that immunity to their progeny for many consecutive generations,” reported lead author Oded Rechavi, PhD, associate research scientist in biochemistry and molecular biophysics at CUMC. “The immunity was transferred in the form of small viral-silencing agents called viRNAs, working independently of the organism’s genome.”

In an early theory of evolution, Jean Baptiste Larmarck (1744-1829) proposed that species evolve when individuals adapt to their environment and transmit those acquired traits to their offspring. For example, giraffes developed elongated long necks as they stretched to feed on the leaves of high trees, an acquired advantage that was inherited by subsequent generations. In contrast, Charles Darwin (1809-1882) later theorized that random mutations that offer an organism a competitive advantage drive a species’ evolution. In the case of the giraffe, individuals that happened to have slightly longer necks had a better chance of securing food and thus were able to have more offspring. The subsequent discovery of hereditary genetics supported Darwin’s theory, and Lamarck’s ideas faded into obscurity. However, some evidence suggests that acquired traits can be inherited. “The classic example is the Dutch famine of World War II,” said Dr. Rechavi. “Starving mothers who gave birth during the famine had children who were more susceptible to obesity and other metabolic disorders — and so were their grandchildren.” Controlled experiments have shown similar results, including a recent study in rats demonstrating that chronic high-fat diets in fathers result in obesity in their female offspring.

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