I often criticize the Intelligent Design Creationists for not coming up with anything other than criticism of evolution. That criticism is perfectly justified as we can see in Casey Luskin's latest posting on
Evolution News & Views:
Back to School Lesson Plans That Actually Help Students Understand Evolution. He's even gone as far as proposing a lesson plan on evolution for grades 4-7. One of the important parts of that lesson plan is the challenges to evolution.
It's Monday, and it's Thanksgiving Day in Canada, so I'm taking a bit of a break. Let's have some fun with Luskin's lesson plan. I'll quote each of his points with a brief response.
Step 3: Learn About the Case against Evolution (1.5 hours). Now students will learn about some of the science that challenges evolution. Watch the DVD Icons of Evolution.
- Ask students to explain the difference between microevolution and macroevolution.
This is far too complicated for public school students. The simple answer is that microevolution describes changes occurring within populations and macroevolution describes the history of life. Macroevolution includes things such as speciation that are not part of microevolution and it also includes things like asteroid impacts, ice ages, and drifting continents in order to explain the history of life. There's an important part of evolutionary theory called "Hierarchical Theory" where proponents argue for higher-level mechanisms of evolution such as species selection. They aren't part of microevolutionary explanations. Thus, microevolution is necessary but not sufficient to explain macroevolution [
Macroevolution].
-The video mentions the Galápagos finches. Do the finches represent an example of microevolution or macroevolution?
It's on the border between microevolution and macroevolution. The value of the work on the Galapogos finches is that the results suggest how new species are formed. They formed from a combination of physical isolation events (different islands) plus microevoutionary events involving natural selection, and random genetic drift. Such speciation events occurred repeatedly in the history of life and these studies show how they can be explained by purely natural causes.
-The video mentions mutations in fruit flies which gave fruit flies an extra pair of wings. Were these fruit flies able to fly better and survive with the extra wings?
No.
-Are mutations helpful or harmful? Ask for examples of harmful mutations? How about helpful ones?
A harmful mutation is one that decreases fitness. There are hundreds of examples of genetic diseases in humans. A beneficial mutation is one that increases fitness. Antibiotic resistance in bacteria is a classic example but so is HIV resistance in humans. Dozens of field studies have shown that beneficial mutations can arise fairly quickly in populations that are challenged by environmental change. Molecular data documents thousand of beneficial changes to genes and enzymes over time.
-What was the Cambrian explosion?
The Cambrian Explosion was a period in the history of life where we see the appearance of new types of animals. The dates are approximately 500 million years ago and the time frame for the visible appearance of these groups ranges from 10-50 million years. It's important to note that the fossils of the Cambrian don't look like any species that are alive today and they don't contain any examples of land life. It's also important to note that the Cambrian explosion doesn't apply to plants, fungus, protozoa, and bacteria.
What caused the appearance of primitive animal groups 500 million yeas ago, over a period of tens of millions of years? Scientists don't really know but there are lots of ideas on the table. One thing that's very clear from molecular evolution is that the origin of the various lineages (phyla) goes back several hundred million years.
-Does the fossil evidence show that species have evolved by small gradual changes, or large sudden changes? Do fossils support Darwin’s theory? Why or why not?
The are many examples of slow gradual changes over millions of year but there are also examples of patterns called
Punctuated Equilibria. In these examples you see very small changes—such as the speciation events in the Galapagos finches—happening at the time of speciation. In other words, the fossil record mimics the sort of thing you see in the Galapagos islands where the small changes occurring at speciation are quickly fixed in the population within ten or twenty thousand years. There's hardly any fossil record of the intermediates showing the transition between these closely related species.
There's nothing in the fossil record suggesting that large sudden changes can occur rapidly. That's a lie propagated by creationists who don't understand evolution and who have a religious agenda that interferes with their ability to do science.
-The video also mentions the origin of life. Does the evidence support the claim that the building blocks of life were present on the early earth? Why or why not?
The origin of life is an interesting scientific problem that hasn't been solved. Although it has nothing to do with evolution, it's clearly related. Some scientists think that life arose in a primordial soup containing abundant supplies of all the necessary building blocks we see today. There is plenty of scientific evidence that some of these building blocks—such as simple sugars and amino acids—can arise spontaneously. In fact, many of them have been detected in outer space. Other scientists prefer scenarios where life began much more simply with very small, highly abundant, chemicals that are still around today in the oceans. It will be interesting to watch for new discoveries as you grow up because science is poised to make significant advances in these areas.
You should keep an open mind on this question and watch for new discoveries from religious leaders that will help you understand the origin of life. It's possible—alghough not very likely—that religious organizations such as
The Discovery Institute will come up with a scientific explanation of how, and when, God created life on Earth.
-Compared to humans, was the first life simple or complex? How about compared to a calculator, computer, or cell phone? Are living organisms more or less complicated than human technology? What do students think?
All available scientific evidence points to a common ancestor that was much more simple than humans, or most other species that are living today. Those primitive ancestors are much less complex than a modern computer because, in addition to having only a few hundred genes (at most), the internal cell biology and biochemistry was undoubtedly sloppy and inefficient. No modern machine is anything like that.
We are at the stage in technology development where it is possible to build better life forms than those that evolved naturally and you should look forward to learning about these new artificial forms of life in the next few years. You might even want to think about a future career in science so you can learn this technology.
). One of them is Brent Kelley, an undergraduate at the University of Alberta in Edmonton, Alberta, Canada.
