Evolution

Originally published February 6, 2005

Evolution vs Creation; Evolution vs Intelligent Design; Creation vs Intelligent Design…

At least part of the problem seems to be that the word evolution is so loaded with emotion and confusion that there is no space to bring a religious component into the picture. So here’s an attempt to define evolution in a way that which perhaps creates some room for God.

My definition of evolution is that it is the collection of changes which happen to living organisms in an ecosystem in response to changes in the ecosystem and mutations of the organisms.

It’s the mutation category which most people think of when evolution is the topic. As a result of some damage to the DNA passed from the progenitors to the offspring, the offspring has a combination of traits which gives it a distinct advantage or disadvantage over its relatives. If the mutation is disadvantageous, the offspring is itself unlikely to reproduce and the effect of the mutation is lost. Otherwise the mutation is retained in that individual’s DNA, and may be passed on to its offspring (or perhaps emerge generations later). If the new traits give the individual a competitive advantage, it may provide for higher survival rates of it and its offspring (and broader access to reproductive partners), and gradually a population of individuals sharing this advantageous trait emerge. In successive generations, the DNA pool contains more and more mutations, and in aggregate they improve the reproductive and survival success of that line of individuals. Eventually the changes from the original species become so great that a different species emerges. This is the process which causes green slime to eventually become H. sapiens. It takes thousands or millions of generations for this to happen. That’s a long time for humans, but not quite so long for bacteria (only minutes elapse between generations). Nonetheless, it happens pretty slowly, and few of us get the opportunity to observe its results.

In business, you sometimes hear people say that evolutionary change isn’t fast enough, something revolutionary needs to happen. Those folks are thinking of evolution in terms of cumulative mutations. They miss the far faster and more dramatic form of evolution: the catastrophic change of environment. We know about the dinosaurs being wiped out by a dramatic change in the planet’s climate, perhaps caused by an asteroid strike. But not every reptile was eradicated, and not every mammal appeared after this event. When the climate changed, populations of species which could survive in the new environment carried on, and the rest died. Species which had the best bodies and brains for the old environment might just barely hang on in the new environment, and species that were marginal in the old environment might find that the sudden disappearance of their prime predators and competitors created a Garden of Eden for them. In one fell swoop, the planet went from domination by cold blooded lizards to warm blooded mammals. Of course, the change wasn’t really this binary. There are lots of organisms on Earth besides mammals and lizards. Some plants died out, and others filled their niche. Insects and bacteria and millions of other species survived, although the relative population sizes may have changed.

This kind of evolution is violent and sudden. Winners become losers and visa versa. The total population of individual organisms plummets, and the populations of those organisms better suited for the new environment begin taking over. This kind of evolution happens right before us. In fact, humanity causes a great number of the environmental catastrophes which drive these evolutionary changes. Here’s some examples:

When farmers spray their fields with insecticides, they kill large numbers of the target ‘pests,’ but not quite all. They also kill many of the predators who would otherwise kill those pests, as well as many other insects, some of whom may have been beneficial to the crops. Many of the population of target pests who survived the spraying did so because they were lucky enough to have a genetic makeup that made them resistant to the insecticide. The accumulation of mutations they had perhaps were never apparent or even useful before the farmer took his sprayer through the field, but on that day it was the key to their survival. If both male and female populations survived (because the necessarily mutations were expressed in both genders) they would happily go about procreating new generations of their species, many of whom would carry the mutation. Eventually, the population of this pest would approach that which it would have been had the pesticide not been sprayed at all. The reaction of the farmer is change pesticides. Same thing happens, except now the pest species has become resistant to both pesticides.

We do the same kind of thing when we take antibiotics, which are just pesticides for bacteria. Our body is a greenhouse for bacteria, most of which are harmless. And many of the bacteria which cause sickness can be defeated by a healthy immune system. But when we get sick, we want to feel better – right now. So we go the doctor and beg for antibiotics. The antibiotics are like a meteor strike to the population of bacteria in our body. Some species are wiped out altogether, some are weeded down to their lucky resistant members, and resistant specie now have the whole body to infect without any competition. If we’re lucky, the bad bacteria were part of the first group, and the bacteria who repopulate our body are the harmless kind.

But chances are, there were some bad guys who were resistant to the antibiotic. Perhaps we beat them down enough that they no longer cause a harmful infection, but the species did survive, and these particular members are resistant to this particular antibiotic. Our immune system may have them under control temporarily, but if we take ill for another reason, this population of bad guys can explode, and we might infect someone else. Now the resistant population is loose, and the antibiotic is no longer effective. With luck, the medical community has another antibiotic which beats down the population of bad guys. But eventually we get back to the same place. It’s just like the farmers with their insect pests.

Some agricultural experts have been saying that its time to just let pests and predators reach a natural balance. Sure some crops will be lost to the pests, but the theory is that the money saved in pesticides and application costs (e.g. fuel for the tractors) more than offset the loss of yield. But this isn’t just about saving money in one particular year. If we keep using more and more radical pest population control measures, the pest populations will just keep getting resistant to more things, until we have nothing acceptable left to kill them. Sure we can find yet one more way to kill the pests, but perhaps it creates genetic damage to the crops which results in undesirable effects on the animals that consume it. Maybe the next wave of a “mad cow” like disease will flow from cattle eating genetically damaged corn.

The “miracle drug” antibiotics of 50 years ago are all but worthless in western countries today. The species of bacteria they were developed to kill have become resistant, and now third and fourth generation antibiotics must be used. Where do you think the most resistant bacteria live? It’s not in cesspools and nasty ponds – it’s in major hospitals. Those rooms and their contents are constantly cleaned with antibacterial solutions to keep down infection. But you can’t kill all the bacteria all the time because some lucky few will have a mutated resistance. The bacteria which live in hospitals have survived the best we have to throw at them. If your body gets infected by one, there may be no antibiotic left which can beat it. If your immune system loses the battle, you die.

Yep, evolution is definitely going on all around us. H. Sapiens is enjoying what may well be the latter half of its time of domination. The catastrophe that changes the balance may well be of our own making.

When Jesus said, “blessed are the meek, for they shall inherit the Earth (Mt 5:5),” he may have been talking about the bacteria and cockroaches.