How fast can evolution operate?
A common arguments against evolution raised by creationist and intelligent design writers is that no significant changes have ever been observed by humans in biological species, so evolution must be regarded only as a “theory.” In a previous Blog, we mentioned how this argument is refuted by recent research results, which document that evolution can operate surprisingly fast — over the course of hours, days or years (certainly within a human timescale).
The rise of antibiotic-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. By analyzing DNA sequences, researchers have identified at least six different families of tuberculosis, and at least one of these appears to be evolving in a potentially very dangerous direction [Lehrman2013]. Some fear that by 2050, up to 10 million persons may die every year from infections that cannot be treated. Developing a plan to avert a “post-antibiotic apocalypse” is a urgent priority in biomedical research [Long2016a].
Along this line, on 27 May 2016 researchers announced that a Pennsylvania woman, who had been diagnosed with a urinary tract infection, was in fact infected with a strain of bacteria that was resistant to colistin, an antibiotic “of last resort” — used only when all other antibiotics have failed. This was the first instance of this strain in the U.S., and more are feared [Moyer2016].
Harvard’s MEGA-plate demonstration
On 8 September 2016, biologists at Harvard University released a video allowing viewers to witness E-coli bacteria developing resistance to an antibiotic agent, before your very eyes [Long2016b]. You can view the video here: VIDEO.
They call their experiment Microbial Evolution and Growth Arena plate (MEGA-plate). Here is how it works: The experiment was constructed in a 2 foot x 4 foot Petri dish, separated horizontally into nine zones. The outermost zones had no antibiotic; the two next inner zones had unit concentration; the next two had 10X this level; the next two had 100X; and the innermost region had 1000X.
At the start of the MEGA-Plate demonstration, bacteria are dropped into the two outermost zones, and soon fully colonize these zones. After a while, bright spots appear on the edges of the next two inner zones, indicating that mutations have arisen and are now spreading through the 1X zones. After some hesitation, they spread to the 10X zones, and then to the 100X zones, and, finally after an extended pause, to the innermost 1000X zone.
Scientists are as impressed as anyone by the demonstration, and are intrigued by its research potential. As Pamela Yeh of UCLA remarks, “It is very exciting and takes us much closer to the real thing.” Michael Brockhurst of the University of York notes similarities between the experiment and the patterns of infection in a person’s lung who is afflicted with cystic fibrosis: “There are some really interesting parallels between those infections and the multiple coexisting wavefronts [on the MEGA-plate].”
Creationists and intelligent design writers have long rejected the notion that evolution can occur. But those unfortunate persons who have been infected by one of these multi-drug-resistant disease strains would certainly disagree! The challenge of scientific research is now to understand how these resistant varieties arise and to develop new approaches to treatment for future victims.