Rapid tomcod ‘evolution by pollution’? Yeah, right … and wrong
Published: 22 February 2011 (GMT+10)
Joanie Côté, Wikipedia.org
The Atlantic tomcod only benefits from its information-losing mutation in the heavily polluted Hudson River.
Headlines have screamed that fish in New York’s Hudson River have ‘evolved’ into ‘super mutants’, able to resist the toxic effects of PCBs (polychlorinated biphenyls) in that heavily polluted waterway. And all this ‘evolution’ has happened in less than 50 years.1
As reported in the respected journal Science,2 researchers have indeed shown that some 95% of the Hudson’s bottom-feeding Atlantic tomcod have become resistant to these poisons. It is the first recorded case of poison resistance (similar to antibiotic resistance or pesticide resistance) developing in vertebrates (creatures with backbones). And this is almost certainly via mutation, which is then favoured by natural selection.
So the fish have adapted to this new environment by a Darwinian mechanism. But as we have already extensively shown in detail (for example, in this article on supergerms), such resistance to poisons in bacteria, for instance, most definitely does not demonstrate the sort of biological change required to have turned microbes into magnolias, mosquitoes and microbiologists. It is in fact demonstrating the opposite, if anything, especially in those cases of antibiotic resistance where mutations have generated the resistance.
This is something that is simple to understand and demonstrate; the germs become resistant due to various forms of damage (which is what mutations—inherited genetic copying mistakes—mostly do) to their internal engineering. A good example is where a germ that uses biological pumps to draw in its nutrition has a mutation that damages the pumps. That makes it harder for it to pump in not just nutrients, but also antibiotics when these are in its environment—in short, it is no longer as good at sucking in the poison that kills it.
So the ones that have this defect do better when there are such poisons around (natural selection—a fact of life). But they are ‘damaged goods’, unable to pump in nutrients as efficiently—so, once the poison is removed from their surroundings, they don’t do as well as the normal, undamaged germs. So the ‘normal’ type of germ will come to dominate the population once more, because it is more efficient at what it needs to do.
This is not ‘evolution’ (as most people understand that word to mean) at all, since that requires a net uphill gain of information, improvements giving greater viability and efficiency, building new and improved biological machinery, not damaging that which exists. In short, even a committed evolutionist should concede that this sort of mutation that ‘breaks things’ is not the sort that he would like to see to demonstrate the viability of his belief in ‘uphill’ evolution.
And—surprise, surprise—despite the media hype, all indications are that the same sort of downhill damage as in the bacterial example just given has taken place in the case of the Hudson tomcod. All such Atlantic tomcod fish have a gene called AHR2. This codes for a receptor protein which in its normal state allows PCBs to bind to it, causing severe problems (some 30 years ago, 94% of Hudson tomcods were found to have a PCB-induced liver tumour, for instance). The Hudson River variety, according to one of the researchers, Dr Mark Hahn of the Woods Hole Oceanographic Research Institution, “appear to be missing two of the 1,104 amino acids normally found in this protein”. This is apparently the result of six of the bases in the gene’s DNA sequence having been deleted (two lots of three bases, each coding for one amino acid).
This loss mutation has damaged the receptor such that PCBs and dioxins cannot bind as readily to it. Mutation happens in one generation, and since in such a poison-rich environment the non-damaged fish would be rapidly eliminated, it’s no wonder (and in keeping with other instances in non-vertebrates of poison resistance) that the mutated gene would spread quickly enough to dominate the population in just a few decades.
Given that these mutant fish are ‘damaged goods’, and in keeping with our comments earlier, it’s also no surprise to read about the Hudson tomcod that “the fish have suffered in other ways. They likely grow slower than other tomcod, and they may have reduced resistance to other dangers.”3
One would therefore expect that these genetically damaged fish would not do as well in less polluted areas, and so again it’s no surprise to read that only “5% of the fish in the nearby, relatively clean waters off Connecticut and Long Island possess the mutated gene.”
Of course. About the only surprise is, why would the same article that made those frank admissions about these damaged, weakened fish have a headline that referred to them as having “evolved” into “super mutants”?
But then, maybe one shouldn’t be surprised there, either. It seems that in this day and age sensationalist headlines that keep reinforcing the idea that there is all this ‘evidence’ of ‘evolution happening’ are just par for the course. If anything, it should encourage us all to get involved much more with passing on the sort of information that can counter this ‘propaganda war’; tell your friends and acquaintances about this site; subscribe to our free email newsletter; give them gift subscriptions to Creation magazine, hand out books and DVDs of quality creation information. And keep yourself informed. Yes, it helps us to keep going and growing, but it is also one way in which all of us can ‘do our thing’ to help combat this relentless onslaught of misinformation. As you get behind us, we can ‘make the bullets’ in this spiritual war, but we need you to help fire them.
- For example, http://www.dailymail.co.uk/sciencetech/article-1358316/Atlantic-tomcod-immune-Hudson-Rivers-toxic-chemicals-just-50-YEARS.html Return to text.
- Wirgin, I., Roy, N.K., Loftus, M., Chambers, R.C., Franks, D.G. and Hahn, M.E., Mechanistic Basis of Resistance to PCBs in Atlantic Tomcod from the Hudson River, Science, 17 February 2011 DOI: 10.1126/science.1197296. Return to text.
- http://io9.com/#!5763610/fish-in-polluted-waters-have-evolved-into-toxin resistant-super-mutants Return to text.