As science theories go, evolution is perhaps the least amenable to experimental observation. The processes are presumed to occur over vast periods of time, the cited evidence is often entombed in rock and subject to much speculation, and the proposed mechanisms are resistant to experimentation.
But with modern methods, much of this may be changing. Until recently it was difficult if not impossible to directly observe the changes in populations of organisms as the result of either incidental or introduced genetic modifications. Simply mapping genomes was a costly and expensive proposition, much less conducting regular experiments which tracked genetic changes. But technology is rapidly advancing in this area, and increasingly scientists are able to make more direct observations about the actual effect of genetic changes in populations of organisms, and directly test the claims of neo-Darwinism (the synthesis of Darwin’s theory of evolution with modern genetics). First a little background on why such experiments are relevant to evolution.
In the modern iteration of evolution, genetic variation is thought to be the product of mutations. Those mutations express themselves in the form of physical traits that act to make individual organisms more or less capable of reproducing in their environment, which in turn affects their ability to pass on those traits to their offspring. If the variation in question confers some beneficial trait, over the course of a number of generations the increase reproductive fitness causes the trait to predominate in that population of organisms. Given sufficient modifications over a sufficient amount of time if the organisms with novel traits become a separate interbreeding population, then a new species comes into existence.
Again, because of the time periods involved, and the fact that the changes occur on an unseen genetic level, this process isn’t very amenable to observation or experimentation; however two recent experiments have allowed researchers to directly observe the propagation of genetic changes in a population of organisms, the first tracking a mutation in a population of fruit flies over the course of 600 generations, and the second observing the effect of a introduced mutation on a bacterial population.
The first paper, published in Nature, details a 30 year experiment observing a selection process acting on the genome of a population of fruit flies. In this case they were chronicling the how a particular adaptation moved through a population – specifically a trait that conferred accelerated development. Fruit flies mate as soon as they mature, so accelerated development (estimated to be 20% faster) would certainly convey a reproductive advantage to individuals with the trait; in fact, the evolutionary expectation is that eventually the trait would ‘sweep’ the population and become fixed in the population. And this would be the evolutionary expectation for a significantly advantageous trait.
What they observed when they surveyed the genomic regions to identify the modifications in the selected population was that there was little difference from the control population. Not only had the beneficial genetic modifications not ‘swept’ the selected population – in fact the frequency of the trait was little different than the control population. As the paper concludes:
Our work provides a new perspective on the genetic basis of adaptation. Despite decades of sustained selection in relatively small, sexually reproducing laboratory populations, selection did not lead to the fixation of newly arising unconditionally advantageous alleles. This is notable because in wild populations we expect the strength of natural selection to be less intense and the environment unlikely to remain constant for, 600 generations. Consequently, the probability of fixation in wild populations should be even lower than its likelihood in these experiments. This suggests that selection does not readily expunge genetic variation in sexual populations, a finding which in turn should motivate efforts to discover why this is seemingly the case.
In short, if the activity failed to occur in the lab under optimal conditions, it is unlikely that traits are going to be transmitted this way in nature. If that is so there is a fundamental flaw in the current evolutionary theory.
In the second case researchers inserted mutations in various loci in a genome in order to determine the effect on the fitness of a population of bacteria. As mentioned before, mutations are seen as essential for the production of new information in Neo-Darwinian evolution. This is problematic when such mutations occur on genes, or portions of the genome that sequence for proteins which are critical to the organism as such a mutation could deleterious to the organism’s survival. To get around this, evolutionists have proposed that mutations can occur on non-sequencing portions of the genome, and thus will produce no such effects – those mutations to non-coding sequences could serve as the raw material for novel genetic sequences.
What researchers found in this experiment however was that the introduction of mutations throughout the genome, whether to coding sequences or non-coding sequences was equally the effects were equally negative:
Even more surprising was the fact that mutations that do not change the protein sequence had negative effects similar to those of mutations that led to substitution of amino acids. A possible explanation is that most mutations may have their negative effect by altering mRNA structure, not proteins, as is commonly assumed.
This certainly casts a pall on the notion that there exist portions of the genome that are amenable to random mutations – if introduction of such mutations to any portion of the genome is equally deleterious to an organism, then there is little room for the acquisition of novel traits through incremental addition of such modifications, a process critical to evolutionary advancement.
Much of this research comports with Michael Behe’s thesis in The Edge of Evolution that the significant genetic leaps required to produce complex novel traits simply aren’t observed in nature.
Evolution has been difficult to test up until now –but as so often happens in science technology has caught up with theory; and in this case the current theory of evolution isn’t fairing so well.