Evolution right before our eyes

Creationist and intelligent design writers have often insisted that whereas minor changes may occur within an established “kind,” nothing fundamentally new can come through “random” or “undirected” evolution. But there are numerous examples of “right before our eyes” evolution in the scientific literature. Here are a few:

  1. 1974 E. Coli experiment. In a 1974 paper Barry Hall and Daniel Hartl identified a gene in the bacterium E. Coli that is responsible for metabolizing lactose, using a complicated three-part process. They removed this gene, and then permitted the bacteria to multiply in a stressed environment containing lactose. Within 24 hours the bacteria had evolved a capability to utilize lactose, by means of a similar but distinct three-part biochemical pathway, involving two mutated genes [Hall1974].
  2. New E. Coli experiment. In a more recent experiment, biologists Richard Lenski and colleagues conducted a 20-year experiment, starting with 12 flasks of E. Coli bacteria, identical except for some neutral markers, and then each day inserting 1/100 of the flask’s liquid (which contained glucose and citrate, among other materials) into a new flask. In this way they followed the course of these bacteria for 45,000 generations. As the generations continued, each of the 12 lines grew progressively better at processing glucose, although each took a different trajectory. Examining the results after 20,000 generations, the experimenters found that for two of the 12 lines, 59 genes had changed their levels of expression, and that all 59 had changed in the same direction in each line — in other words, the two lines had independently “discovered” virtually the same improved scheme for glucose metabolism. Later in the experiment, shortly after generation 33,000, the average population of one of the lines shot up by a factor of six above the others. The investigators found that this line had developed the ability to utilize citrate, which bacteria normally cannot use, by means of a remarkable combination of two distinct mutations [Lenski1994].
  3. Japanese nylon-eating bacteria. Japanese biologists recently discovered a bacterial species that thrives in nylon waste. It turns out that these bacteria had undergone a “frame shift” mutation, where an extra base pair had been inserted into the bacteria’s DNA. This mutation significantly changed the bacteria’s biology, since a long series of amino acids were altered, but by remarkable chance this alteration endowed the bacteria with the facility to metabolize nylon, albeit not very efficiently [Negoro1994].
  4. The Milano mutation. Scientists recently discovered that certain persons in an Italian community, all descended from a single individual several generations back, possess a genetic mutation that increases “good” cholesterol and provides an effective antioxidant, thus resulting in measurably improved cardiovascular health [Musgrave2003].
  5. Antiobiotic-resistant diseases. Perhaps the best-known examples are the recent evolution of new strains of tuberculosis that are resistant to all known anti-TB drugs, and drug-resistant strains of HIV that in many cases evolve within the body of a single patient. For instance, researchers now fear that HIV, which has been largely kept in check by antiretroviral drugs in first-world countries, is now poised for a rapid upsurge, due to the emergence of multi-drug-resistant strains of HIV that have been documented in several large U.S. and European cities. What’s more, as access to antiretroviral drugs increases in poorer countries, it is likely that they will also see resistance grow as well [Coghlan2010].
  6. Tibetan high-altitude genes. In 2010, researchers at the University of Utah and Qinghai University in China have found that natives of the Tibetan highlands have evolved ten unique genes that permit them to live well at very high altitudes. Because of these genes, Tibetans have more efficient metabolisms, do not overproduce red blood cells in response to thin air, and have higher levels of nitric oxide, which helps get oxygen to tissue. A even more recent study found a total of 30 genes that were distinct in the Tibetan population, and concluded that this change constitutes the fastest documented case of human evolution [Wade2010b].
  7. New York City fauna. Present-day “before your very eyes” evolution is not restricted to distant lands. In 2011 researchers at the New York University Medical center noted that tomcod in the Hudson River appeared to have acquired resistance to PCBs, which otherwise cause deformities in fish larvae. As it turns out, almost all of these fish share a mutation known as AHR2, which inhibits PCB action and thus shields the fish from harm. This mutation is completely missing from tomcod that live in northern New England and Canada. Also, researchers at the City University of New York recently identified a set of mutations spanning more than 1000 genes that are present in all white-footed mice in New York City, but which are missing from mice in Harriman State Park, just 45 miles north. Many of these genes are involved in fighting bacteria, while others appear to aid in coping with exposure to chemicals [Zimmer2011].

Additional examples and complete references are available at Novelty. This post was entered in the NESCent Blog Contest.

References

  1. [Coghlan2010] Andy Coghlan, “Drug-Resistant HIV Set to Surge,” New Scientist, 15 Jan 2010, available at Online article.
  2. [Hall1974] Barry G. Hall and Daniel L. Hartl, “Regulation of Newly Evolved Enzymes,” Genetics, vol. 76 (1974), pg. 391-400.
  3. [Lenski1994] R. E. Lenski and M. Travisano, “Dynamics of Adaptation and Diversification: A 10,000-Generation Experiment with Bacterial Populations,” Proceedings of the National Academy of Sciences, vol. 91 (1994), pg. 6808-6814.
  4. [Musgrave2003] Ian Musgrave, Steven Pirie-Shepherd, and Douglas Theobald, “Apolipoprotein AI Mutations and Information,” 2003, available at Online article.
  5. [Negoro1994] Negoro, S., K. Kato, K. Fujiyama and H. Okada, “The Nylon Oligomer Biodegradation System of Flavobacterium and Pseudomonas,” Biodegradation, vol. 5 (1994), pg. 185-194.
  6. [Wade2010b] Nicholas Wade, “Scientists Cite Fastest Case of Human Evolution,” New York Times, 1 Jul 2010, available at Online article.
  7. [Zimmer2011] Carl Zimmer, “Evolution Right Under Our Noses,” New York Times, 25 Jul 2011, available at Online article.

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