Saturday, 1 March 2014
Creationists are right—there is only microevolution
Evolutionary change can only happen because the process of copying DNA, though amazingly accurate, is not perfect. Errors occur. Measuring spontaneous mutation rates is complex but there is probably a lower limit of 0.1 mutation per generation for simpler genomes but it can be up to 1,000 times higher than this for complex genomes. These errors can affect genes in several ways: change a protein; change when a gene switches on or off; trim off pieces of DNA, insert pieces of DNA and so on.
Most of these changes are likely to be harmful but some will be beneficial or neutral and may be passed to future generations. This is how natural variation occurs in a species—we are not all identical. Some of us are bigger, faster runners, higher jumpers, smarter, have better vision and so on.
If many changes were to occur in one individual, the probability that these changes would be beneficial or neutral becomes astronomically small. This is why evolution occurs in very small steps and that is why (almost) all evolution is microevolution.
But evolutionary changes are cumulative. Over many, many generations, very small changes could amount to substantial changes, especially if the organism lives in a changing or hostile environment.
When a species becomes separated into geographically remote populations living in different environmental circumstances, the two groups are LIKELY to evolve differently to adapt to their differing environments.
Imagine that a population of small mammals separates into two groups. Perhaps some go roaming to distant places to find food or some cross a river and some don’t. One group may find itself in savannah—flat grasslands with few places to hide. The other group may end up in a wooded area where climbing a tree is a safe haven.
Both groups are subject to predators. In the savannah, our mammals are chased and the slowest are likely to become another animal’s dinner. Through this selective pressure, the individuals best suited to running (because of the natural variation in the population) would reproduce most successfully and the genes that confer running speed or endurance would become more widespread throughout the group.
Imagine this process continued for hundreds or thousands of generations during which time, the predators also became better adapted to chase our mammals.
Over this time many changes could occur to our mammals. Their rear legs may become stronger and longer. Their leg muscles might increase in size and, perhaps in composition to give faster acceleration or more endurance.
Their lungs may increase in capacity, their eyesight and sense of small may improve to give earlier warning of predators. They may lose body hair to improve cooling and allow faster running speeds and more endurance.
All these changes occur naturally, without any direction, because the most capable individuals in the population will have more offspring. Natural variations will continue to appear and build on the natural selection that has occurred over the past generations. Evolution is a cumulative process building on whatever has happened before.
Over a great many generations, these mammals would be unrecognisable compared to their body-form when they left their parent population. There would have been so many cumulative genetic changes that they would no longer be able to breed with their parent species. A new species would have evolved.
So creationists are right—there is only microevolution.
Macroevolution = microevolution + environmental pressure + time.
Macroevolution is an inevitable consequence of microevolution. In missing this final step, creationists are not right; they are dead wrong.
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About Me
- Nildogma
- As a 20-year-old I was insatiably curious about the world and passionate about rejecting superstitions and all kinds of false beliefs. I still am today. Sometimes when people believe things that are not true, it make little or no difference but sometimes the consequences can be disastrous and deadly. Now, I do what I can to help people improve their thinking skills, especially in how they impinge on core beliefs, such as cultural values and religious beliefs. I have an active Facebook page for which I create memes and write articles almost daily. I also engage people in on-line debates. You can find me here: https://www.facebook.com/bill.flavell.1 I lecture at universities around the world and present or debate at public meetings. I also, draw on my management consultancy background to help freethought groups, almost anywhere in the world, to get organised, develop strategy and improve their media and presentation skills. If you would like me to present at your university or for your church group or freethought group, please contact me.
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