Testing the Limits


Evolution would require an enormous amount of change. Modern laboratory experiments have tested bacteria’s ability to change. Is this ability truly unlimited?

Evolutionists face an insurmountable challenge. They believe that all living things descended from a single-celled common ancestor over the course of 3.5 billion years. For this to happen, an enormous amount of change had to occur. Massive amounts of novel genetic information had to be added to DNA on how to make brains, eyes, blood cells, and everything else that exists in modern living things but didn’t exist in the supposed original single-celled ancestor.

What could possibly produce all this change? Evolutionists credit one major source: genetic mutations. This mechanism must have enough power to add the seemingly endless amount of information that resulted in plants, animals, and humans. For evolutionists, mutations are the “magic bullet” that can do—and have done—virtually anything and everything.

But what does science in the laboratory show us? Are there limits to change? If so, then evolution would be dead in the water.

Historical vs. Observational Science

We can’t observe what occurred in the distant past. No human has observed billions of years of evolution through mutations, and no human was present to observe God’s creation in six days. So how can we know which is true?

We don’t need laboratory studies to answer the question. God gave us His eyewitness account in Genesis. Since we know that He cannot lie (Titus 1:2) and that His Word is true (Psalm 19:7–11), we can trust that His account of the past, not evolution, is correct. So in a sense the Bible is our final answer when answering people’s questions about evolution; God’s Word is the ultimate authority for every Christian.

But that doesn’t mean we don’t or shouldn’t use scientific evidence. God’s Word is true, so what we understand from observational science should confirm—or at least be consistent with—the Bible. The inference from Scripture is that all creatures were to reproduce according to their kind (Genesis 1, 6, and 8), so we expect to see organisms making limited changes to adapt to changing environments, but not evolving into totally different kinds of organisms.

Although we can’t directly observe or test evolution or creation, we can use observational science—observable, testable, and repeatable science—to see which view of the past aligns with the evidence today.

Scientists have been carefully studying mutations in bacteria to see whether they have the power to produce essentially unlimited change or whether change is limited. Two major, long-term experiments have examined the common gut bacteria Escherichia coli to see how it adapts to changing environments. These famous experiments are often cited as prime examples of unlimited “evolution in action.” But on closer examination, they confirm just the opposite: limited change.

Evolving Ability to Break Down Lactose

Dr. Barry Hall, professor emeritus of the University of Rochester, New York, has done research showing how bacteria react to adverse environmental conditions, like starvation. Amazingly, bacteria can initiate mechanisms in their genetic programming to speed up the occurrence of mutations that allow them to survive in difficult environments.

E. coli normally has the ability to use a common sugar, called lactose, as a food source. Hall was able to mutate a strain of E. coli so that it could no longer use lactose (as a result of mutations in the lac genes).1 He then put the mutant E. coli back into an environment where lactose was the only food source. The only way the E. coli could survive was to develop the ability to use lactose again. After a period of time, E. coli developed this ability. How?

The answer was mutations in other genes that the E. coli already possessed (called ebg genes). When these genes are not mutated, the bacteria can use a small amount of lactose, but not enough to survive. In response to the starvation conditions, mechanisms were initiated that enhanced the ebg genes’ ability to use lactose. No new or novel traits were gained; preexisting genes merely made a very limited change, enhancing a function they already had.

Interestingly, Hall predicted that if both genes (the lac genes and the ebg genes) were made nonfunctional through mutations, additional mutations would occur in other genes so E. coli could regain the ability to use lactose.2 However, “despite extensive efforts,” Hall was unable to get such E. coli to survive on lactose.

Mutations are limited and cannot originate new and novel traits necessary for molecules-to-man evolution.

Despite the evidence, Hall concluded, “Obviously, given a sufficient number of substitutions, additions, and deletions, the sequence of any gene can evolve into the sequence of any other gene.”3 But Hall’s own experiments showed otherwise—a gene cannot just become a completely different gene doing something completely different. Mutations are limited and cannot originate new and novel traits necessary for molecules-to-man evolution.

Evolving Ability to Break Down Citrate

In 1988, Dr. Richard Lenski, an evolutionary biologist at Michigan State University, began growing cultures of 12 identical lines of E. coli. More than 50,000 generations and 27 years later, the experiment continues. Lenski has been observing changes in the E. coli as they adapt to laboratory conditions.

For example, some lines have lost the ability to use a sugar, repair DNA, or even move.4 In other words, they’ve gotten lazy, as they’ve adapted to the easy life in the lab, where food is plentiful! If they were grown in a natural setting with their normal counterparts, competing for limited resources, the mutant bacteria wouldn’t stand a chance.

In 2008, Lenski’s lab discovered a new change in one of their lines of E. coli. A New Scientist writer proclaimed, “A major innovation has unfurled right in front of the researchers’ eyes. It’s the first time evolution has been caught in the act of making such a rare and complex new trait.”5 But is this what really happened?

Normal E. coli has the ability to utilize the substance citrate as a source of carbon and energy but only when oxygen levels are low. Lenski’s lab discovered that one of their E. coli lines could now use citrate when oxygen levels are normal.6 It’s easy to see that this was not the “making of a rare and complex new trait” because E. coli already had the ability to use citrate! These were mutations that changed when citrate could be used.7

The types of changes in E. coli simply altered (in a very limited way) genetic information and functions that were already present. These changes did not add new genetic information that over millions of years could lead from microbes to man.

Bacteria—Designed to Change

Bacteria are “master adapters.” God designed them with special genetic mechanisms that can alter their own genetic information, and He even gave them the unique ability to acquire genetic information from other bacteria (see “Bacteria’s Unique Design—Pooling Resources,” Answers, January–March 2015, pp. 52–54). Bacteria serve vital roles in a variety of difficult environments. So God gave them both of these special processes to help them survive where they would have to adapt or die.

Yet their mutations—or any other type of genetic change—are limited so that bacteria can continue to function in the beneficial roles God designed for them.

This so-called “evolution in action” is likely not applicable to other types of organisms. It is widely known that bacteria differ greatly from other living things, yet these differences are rarely mentioned when it comes to research on evolution.8 Many evolutionists think that the changes in bacteria have continued in many other types of organisms over millions of years. Yet this thinking is problematic. Here are just a few reasons:

Bacteria are single cells, so changes need to occur in only one cell to be passed to the next generation. In multicellular organisms, changes would have to occur in multiple cells of a given tissue or organ to benefit the organism and reappear in a germ cell (sperm or egg) to be passed to the next generation.

Bacterial population sizes are usually large and generation times short. So bacteria can test different mutations quickly to find the most beneficial changes, and populations can recover quickly. For other living things, small population sizes and longer generation times are the norm, making such trial and error deadly.

Bacterial DNA is much more streamlined than the DNA of other living things. The genes in bacteria perform separate and distinct functions, so a mutation will likely affect only one function (for instance, a gene produces a single protein but nothing else). The genetic sequences of humans, in contrast, often have multiple overlapping functions (for instance, a sequence could be for a gene and regulation). So a mutation is likely to affect multiple functions, and one of the effects is bound to be detrimental.

Even with all the genetic changes that occur in bacteria, they still remain bacteria. Because of their short generation times and large population sizes, bacteria have reproduced far more than humans or animals could in billions of years. Yet the changes have led to nothing more than minor variations within the bacterial populations, not molecules-to-man evolution. If even the “master adapters” can’t evolve into something different, as observational science confirms, there is no chance that any other creature will be able to achieve this feat.


Experimenting with Change in Bacteria

Two famous sets of experiments have shown that mutations in bacteria enable them to utilize food in new ways. Is this “evolution in action”? On closer examination, the changes in bacteria merely altered preexisting genes and their regulatory components; they didn’t produce the types of changes necessary for molecules-to-man evolution.

Hall's Lactose Experiment Evolution Requires Experimental Observations Showed
Dr. Barry Hall developed a strain of E. coli bacteria that lost its ability to break down the sugar lactose (through a cluster of genes called the lac genes). A mutant strain later began breaking down lactose with another cluster of genes it already possessed (called the ebg genes).Gain of novel structures and functionsThe E. coli regained preexisting structure and function. In other words, E. coli initially had the ability to break down lactose (lac genes), it lost that ability through mutation of those genes, and then it regained that ability through mutation of similar but different genes (ebg genes).
Gain of novel genetic information that is directionalPreexisting genetic information was altered, leading to nondirectional change. In other words, mutations in the ebg genes enhanced the bacteria’s ability to break down lactose, but E. coli remained E. coli.
Unlimited genetic changeThe genetic change was limited. In other words, no alterations in any other gene in E. coli occurred that allowed it to break down lactose when the lac and ebg genes were made nonfunctional.
Lenski's Citrate Experiment Evolution Requires Experimental Observations Showed
Dr. Richard Lenski observed a strain of E. coli gaining the ability to break down citrate under normal oxygen levels. Before this change, it only happened under low oxygen levels.Gain of novel structures and functionsThe E. coli did not gain novel structure or function. In other words, E. coli already had the ability to break down citrate.
Gain of novel genetic information that is directionalPreexisting genetic information was altered, leading to nondirectional change. In other words, mutations in citrate regulation allowed E. coli to use citrate under different conditions, but E. coli remained E. coli.
Dr. Georgia Purdom is a speaker and researcher for Answers in Genesis. She earned her doctorate from Ohio State University in molecular genetics and spent six years as a professor of biology at Mt. Vernon Nazarene University.

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  1. Georgia Purdom and Kevin L. Anderson, “Analysis of Barry Hall’s Research of the E. coli ebg Operon,” in the Proceedings of the Sixth International Conference on Creationism (Pittsburgh, Pennsylvania: Creation Science Fellowship, 2008): 149–163.
  2. Barry G. Hall, “Evolutionary Potential of the ebgA Gene,” Molecular Biology and Evolution 12 (1995): 514–517.
  3. Ibid.
  4. Scott Whynot, “Hijacking Good Science: Lenski’s Bacteria Support Creation,” August 13, 2014, https:// answersingenesis.org.
  5. Bob Holmes, “Bacteria Make Major Evolutionary Shift in the Lab,” New Scientist, June 9, 2008.
  6. Zachary Blount et al., “Historical Contingency and the Evolution of a Key Innovation in an Experimental Population of Escherichia coli,” PNAS 105 (2008): 7899–7906.
  7. Zachary Blount et al., “Genomic Analysis of a Key Innovation in an Experimental Escherichia coli Population,” Nature 489 (2012): 513–518.
  8. Kevin L. Anderson and Georgia Purdom, “A Creationist Perspective of Beneficial Mutations in Bacteria,” in the Proceedings of the Sixth International Conference on Creationism (Pittsburgh, Pennsylvania: Creation Science Fellowship, 2008): 73–86.


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