Does Natural Selection Weed Out Harmful Mutations?

A model of the influenza virus (Public Domain Image)
It is generally assumed by evolutionists that natural selection tends to “weed out” harmful mutations. After all, if a mutation is harmful to an organism, that organism will be less fit to survive and less likely to pass on that mutation to its progeny. While this idea makes perfect sense, it is not clear how effective natural selection can be at its job.

In his book Genetic Entropy and the Mystery of the Genome, award-wining geneticist and young-earth creationist Dr. John C. Sanford argues that most mutations simply don’t produce a strong enough effect to influence natural selection. As a result, organisms continue to build up deleterious mutations as time goes on. This leads to an erosion of the genome. As he puts it:1

While selection is essential for slowing down degeneration, no form of selection can actually halt it. I do not relish the thought, any more than I relish the thought that all people must die. The extinction of the human genome appears to be just as certain and deterministic as the extinction of stars, the death of organisms, and the heat death of the universe. (emphasis his)

While he quotes a lot of experimental research to support his findings, he has never been able to demonstrate this effect directly…until now. He obviously hasn’t shown that the human genome is deteriorating, but last year he and young-earth creationist Dr. Robert W. Carter published (in a standard, peer-reviewed journal) the results of some of their research, which directly demonstrate that even when natural selection is working hard, it doesn’t seem to do a good job of getting rid of harmful mutations.

Continue reading “Does Natural Selection Weed Out Harmful Mutations?”

Another Study that Confirms Homeschool Graduates Outperform Their Peers in College

A happy graduate (Click for credit)

Last week, I spoke at the Great Homeschool Convention in Greenville, South Carolina. It was very well attended, and other than a fire alarm that interrupted one of my talks, it ran really smoothly. I gave two brand-new talks at this convention, and they were both done with Diana Waring, whose high school history curriculum is truly wonderful.

One of these new talks was on the myths that you find in textbooks. It started off with the myth that ancient people thought the earth was flat. There is simply no truth to such an absurd idea. As early as 200 BC, natural philosophers knew the circumference of the earth, and the earliest Christian writers who mention the shape of the earth (such as Basil of Caesarea – c. 330-379) mention the spherical shape of the earth as an accepted fact. No one thought that Columbus was going to sail off the edge of the earth. His problems getting funding involved people not thinking he could carry enough supplies to make a voyage all the way around the earth. The other talk was based on a study by Dr. Harold McCurdy, which I have already discussed here.

While the talks I gave were enjoyable, as usual, the most interesting thing that happened occurred as a result of someone asking me a question. One of the solo talks I gave was called Why Homeschool Through High School. As a part of that talk, I discuss studies in which homeschool graduates are compared to graduates of traditional schools when it comes to their performance in college. Not surprisingly, the homeschooled students do much better in college than their traditionally-schooled peers.

After the talk, a homeschooling parent who is also a college professor asked me a very interesting question. He asked me if any study had attempted to measure not the performance of homeschool graduates at the college level, but instead the preparation that homeschool graduates have when they arrive at college. After all, he said, a student can perform well at the college level even when he is unprepared, as long as he has the ability to learn on his own. I told him that the studies I had seen focused on performance, but I would take another look at the literature and see what I could find.

Well, it turns out that such a study has been done. It is a PhD dissertation, which is why I hadn’t seen it in the academic literature. It was done by a student at the University of Nebraska, Lincoln, and it at least partially addresses the question that the homeschooling parent asked.

Continue reading “Another Study that Confirms Homeschool Graduates Outperform Their Peers in College”

The Appendix Is Now So Important That It Supposedly Evolved Many Different Times!

This medical image shows the appendix coming from the large intestine. (Click for credit)
The appendix is a tube-like structure that extends from the cecum, a small pouch that forms the beginning of the large intestine. In the medical image on the left, you can see it because it is filled with a contrast medium, as is the large intestine. For a long, long time, evolutionists have told us that the appendix is useless. It is a leftover vestige from when our ancestors depended heavily on vegetation for food. We have evolved out of such dietary needs, and as a result, we don’t need an appendix anymore. So the appendix we have today is just a shriveled remnant of what used to be a large, complex cecum in our ancestors. Here is how the Cambridge Advanced Learner’s Dictionary defined the appendix in 2008:1

BODY PART: 1 (plural appendixes) a small tube-shaped part which is joined to the INTESTINES on the right side of the body and has no use in humans
[emphasis in original]

Of course, anyone who has been reading this blog for a while knows what the scientific evidence actually says: The appendix is not useless in any way. As a recent study tells us:2

Substantial evidence supports the view that the cecal appendix is an immune structure primarily functioning as a safe-house for beneficial bacteria, and comes from a range of disciplines, including medicine, epidemiology, immunology, and microbiology.

In order to salvage what they can, most evolutionists who know about the recent evidence now admit that the appendix has function, but they still insist that it is vestigial. They argue that the appendix evolved this new function once the old function was no longer needed.

At least some evolutionists, however, are more interested in what the data actually say. The authors of the study in reference (2) have looked at the data and have come to the conclusion that the appendix is not vestigial in any way. Instead, it is so important that it has evolved independently at least 32 separate times throughout the course of mammalian evolution!

Continue reading “The Appendix Is Now So Important That It Supposedly Evolved Many Different Times!”

Dr. Gish Dies at Age 92

Dr. Duane T. Gish (Click for credit)
According to Answers in Genesis, an icon of the modern young-earth creationist movement has passed into Glory. Dr. Duane T. Gish was a popular author among creationists, especially in the 1970s, 1980s, and 1990s. I read many of his books over the years, including Evolution: The Challenge of the Fossil Record, Creation Scientists Answer Their Critics, and Evolution: The Fossils Still Say No! While I did not agree with everything he wrote, I found his books incredibly helpful.

He was probably best known for his willingness to debate those who disagreed with him. He is said to have taken part in more than 300 public debates on the creation/evolution controversy. I always admired him for that. I never had the chance to meet Dr. Gish in this life, but I certainly look forward to doing so in the next.

Under the wide and starry sky
Dig the grave and let me lie:
Glad did I live and gladly die,
And I laid me down with a will.

This be the verse you ‘grave for me:
Here he lies where he long’d to be;
Home is the sailor, home from the sea,
And the hunter home from the hill.

-Requiem by Robert Louis Stevenson.

Homing Pigeons May Hear Their Way Home

These homing pigeons can usually find their way home over very long distances. (Click for credit)
Homing pigeons have been bred to be able to find their way home, almost no matter where they are released. They have been used for more than 2,500 years to deliver messages in a fast, reliable way. For example, a homing pigeon was used to deliver the results of the first Olympiad back in 776 BC.1 Because they have been used for such a long time, scientists have tried to figure out how pigeons are able to navigate their way from an unknown location back to their home. While scientists have been able to figure out some aspects of homing pigeon navigation, the details haven’t been entirely worked out.

It was once thought that homing pigeons use visual landmarks to help in their navigation, but experiments in which the pigeons’ eyesight was reduced using frosted contact lenses showed that’s not correct. Other experiments demonstrate that homing pigeons can sense the earth’s magnetic field, but many of those same experiments also show that disrupting that sense doesn’t always end up leading the pigeons astray. In addition, some experiments indicate that homing pigeons use the position of the sun in the sky to orient themselves, but that can’t be the entire explanation, either, because pigeons can navigate even on very cloudy days. It seems, then, that pigeons use a wide variety of strategies to navigate their way home.2

The mystery of homing pigeon navigation deepened back in 1997, when the Royal Pigeon Racing Association decided to celebrate its 100th year anniversary by releasing 60,000 pigeons in the south of France. These pigeons came from homes throughout southern England, and they were expected to be able to reach those homes in a few hours. While a few thousand of them ended up returning to their homes over a period of a few days, most never made it back.3

Over the years, several hypotheses have been put forth to explain why those pigeons never made it home. One of them suggests that the pigeons’ navigation was disrupted by the sonic boom of the Concorde jet whose flight path crossed that of pigeons. A recent study by Dr. Jonathan T. Hagstrum adds some support to this hypothesis.

Continue reading “Homing Pigeons May Hear Their Way Home”

Nature’s Farmers Are Pretty Smart!

The Central American agouti collects seeds and buries them for later use. (Click for credit)

When I was in Costa Rica last year, I saw several Central American agoutis, such as the one pictured above. I didn’t know anything about them, so when I got back home, I looked up some information. They can be omnivorous, but they prefer to eat seeds and fruit. One of their interesting behaviors is to follow troops of monkeys. They “hang out” underneath the trees that the monkeys climb, and they eat the fruit that the monkeys drop or inadvertently shake off the trees.1

Another really interesting thing about the Central American agouti is that it’s a scatter hoarder.2 This means it collects seeds and buries them in multiple locations. It remembers these locations and returns to them when food is scarce. However, it doesn’t just bury them once and leave them there. It often revisits its stores of seeds, digs them up, and reburies them somewhere else.

While this behavior is beneficial to the agouti (it provides storehouses of food for when food is scarce), it is also beneficial to the trees that drop the seeds. That’s because the agouti rarely uses all of its stored seeds. As a result, some of the buried seeds grow and develop into new trees. This means that the Central American agouti is, in fact, a “farmer” for the trees. It moves seeds away form the tree that drops them and plants the seeds so they can grow into new trees.

Why is this beneficial to the trees? If a seedling grows too near the tree that dropped the seed, it ends up competing with its parent tree. That’s not good for the parent or the seedling. By carrying the seed far from the tree and planting it, the agouti allows the seedling the chance to grow without competing with its parent. Pretty nifty, huh? Well, recent research shows its even niftier than that. It turns out that these “tree farmers” are smarter than we originally thought.

Continue reading “Nature’s Farmers Are Pretty Smart!”

Fully Human

The Home Educating Family Association is a wonderful organization that provides all sorts of useful resources to homeschoolers. They publish a magazine called (not surprisingly) Home Educating Family. Recently, they asked me to contribute to their first issue of 2013, which focuses on pro-life topics. I ended up writing two pieces for them. The first one is entitled “My Little Girl,” and it discusses our experience of adopting a teenager (who just turned 34!). It was probably the most difficult piece I have ever written, as it brought up all sorts of (mostly wonderful) memories. I had such a hard time finding the words I needed to convey what I felt, and then I had a hard time proofreading the piece because of my tears! The article is not available on the internet, so if you want to read it, you will need to get the print magazine.

The other article didn’t make it into the print magazine, so it ended up being posted on the Home Educating Family Association blog. It is essentially a composite of two blog posts I wrote previously discussing how a baby in the womb is fully human. It is not emotional, but some might find it interesting. If you care to read the piece, you can find it here.

Why (and How) Your Skin Wrinkles Underwater

When immersed in water for a long time, the skin on your hands and feet wrinkles.
(Photo by Brenderous, click for full credit)

Almost everyone has experienced it. When you have been soaking in the bathtub, swimming, or just washing dishes for a long time, the skin on your fingers (and toes) wrinkles. From a scientific point of view, there are at least two questions to consider: (1) How does this happen? and (2) Why does this happen? Most textbooks explain (often incorrectly) the how, but I haven’t found any that explain the why. It seems that over the years, scientists have been studying this, and in the end, they have mostly answered both questions.

Let’s start with the “how.” A lot of textbooks and websites incorrectly explain this part. They say that it is the result of your skin absorbing water and swelling. It turns out that’s not true at all. More than 70 years ago, scientists showed that if certain nerves to the hand are damaged, its skin will not wrinkle, no matter how long it stays underwater.1 Over the years, other scientists have investigated water-induced wrinkling, and it seems to be the result of a process initiated by the nervous system.

Your skin is made of two layers: the epidermis (the layer you see) and the dermis (the layer underneath that contains blood vessels). When your hands and/or feet have been underwater for a long time, your nervous system tells the blood vessels in your dermis to constrict. This reduces the volume of the dermis, which in turn reduces the tension with which the epidermis is stretched. As a result, the epidermis “relaxes,” forming wrinkles.2

This answer is interesting enough, because I have long taught the incorrect explanation for how your skin wrinkles underwater. I am glad that I learned I was wrong on the point, and I will now start teaching the correct explanation. However, the “why” question is also very interesting, and a couple of recent studies have provided a good answer for that question as well.

Continue reading “Why (and How) Your Skin Wrinkles Underwater”

Human and Chimp DNA Only 70% Similar, At Least According to This Study

A chromosome-by-chromosome comparison of chimpanzee and human DNA. The chimp DNA was cut into slices of varying lengths (see legend on the right), and a similar sequence was searched for on the relevant human chromosome, which is shown on the horizontal axis.
(Copyright Answers in Genesis, published at http://www.answersingenesis.org/articles/arj/v6/n1/human-chimp-chromosome in a study by Jeffrey P. Tomkins)

PLEASE NOTE: The results of this study are known to be wrong due to a bug in the computer program used. A new study that uses several different computer programs shows an 88% overall similarity.

I have written about the similarity between human and chimpanzee DNA three times before (here, here, and here). It’s an important question for creationists, intelligent design advocates, and evolutionists alike, since the chimpanzee is supposed to be the closest living relative to human beings. As a result, a comparison of chimp DNA to human DNA gives us some idea of what the process of evolution would have to accomplish to turn a single apelike ancestor into two remarkably different species like chimpanzees and people.

Early on, it was widely thought that human DNA and chimp DNA were 99% similar. As I discussed in my first post on this subject, that was based on a very limited analysis of only a minute fraction of human and chimp DNA. Now that the entire set of nuclear DNA (collectively called the “genome”) of both humans and chimpanzees have been sequenced, we now know that the 99% number is just plain wrong. Interestingly enough, however, even though both genomes have been fully sequenced with a reasonable amount of accuracy, no one can agree on exactly how similar the two genomes are.

Why is that? Because comparing genomes is a lot harder than you might think. While we know the sequence of the chimp and human genomes really well, we don’t understand the DNA itself. Indeed, there are large sections of DNA that seem to be functional, but we simply have no idea what they do. As a result, comparing the genomes of two different species can be very, very tricky.

Continue reading “Human and Chimp DNA Only 70% Similar, At Least According to This Study”