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Wednesday, January 28, 2015

Scientists Are Still Trying To Figure Out Gecko Feet

Posted by jlwile on January 15, 2015

The underside of a gecko's foot as seen through glass (click for credit)

The underside of a gecko’s foot as seen through glass (click for credit)

Geckos are lizards that have an uncanny ability to crawl on virtually anything. They effortlessly climb up glass windows without slipping, and they can even crawl on a smooth surface when they are upside down! What gives them this incredible ability? A popular chemistry textbook explains it this way:1

…the gecko uses van der Waals forces to attach itself to surfaces and employs a special technique to disengage from that surface. Van der Waals forces exist between any two surfaces, but they are extremely weak unless relatively large areas of of the two surfaces come quite close together. The toe of a gecko is covered with fine hairs, each hair having over a thousand split ends. As the gecko walks across a surface, it presses these stalks of hairs against the surface. The intimate contact of a billion or so split ends of hairs with the surface results in a large, attractive force that holds the gecko fast. Just as easily, a gecko’s foot comes cleanly away. As the gecko walks, its foot naturally bends so the hairs at the back edge of its toes disengage, row after row, until the toe is free.

I have used this explanation myself when lecturing about van der Waals forces. It sounds like scientists have the gecko’s climbing ability all figured out, doesn’t it? Not surprisingly, however, the gecko’s climbing ability is even more complex than we imagined. As a result, scientists still haven’t completely figured it all out.

The best way to understand what I mean is to look at a bit of history. Back in 1904, German scientist H.R. Schmidt thought that perhaps the gecko employed electrical charges to stick to surfaces. After all, opposite charges attract one another, so if a gecko could induce its feet to develop one charge and the surface to develop the opposite charge, the resulting attractive force could hold the feet to the surface.

About three decades later, another German scientist, Wolfgang-Didrich Dellit, did a simple experiment to test that hypothesis. He shot X-rays at the air surrounding a gecko’s feet while it was on a smooth metal wall. Those X-rays should have ionized the air around the gecko’s feet and neutralized any charge on the wall’s surface. This would have negated any electrical force between the gecko’s feet and the wall, and the gecko should have fallen off the wall. However, after repeated attempts, he couldn’t get a gecko to even slip.2 As a result, scientists ruled out the possibility that electrical charges had anything to do with a gecko’s climbing ability.

Dellit also tested other possible explanations, including that geckos used suction to hold to surfaces, and each was ruled out. Eventually, electron microscopes were used to analyze gecko feet. Once the toe hairs and their “split ends” were seen, the van der Waals forces explanation given by the chemistry text I quoted above was suggested. In the year 2000, a study in Nature confirmed the explanation. It directly measured the force of a single hair from a gecko’s foot, confirming that van der Waals forces were at play.3 As a result, van der Waals forces have been considered the complete explanation for a gecko’s remarkable climbing ability…until now.

WAIT! There is more to read… read on »

An Update On The Triceratops Fossil That Contained Soft Tissue

Posted by jlwile on January 7, 2015

A triceratops skull (click for credit)

A triceratops skull (click for credit)

In March of 2013, I wrote about soft tissue that had been found in the fossilized remains of a Triceratops horridus, which is supposed to be about 65 million years old. One of the scientists who found the tissue and published a paper on it in the peer-reviewed literature1 (Mark Armitage) was subsequently fired from his position at California State University Northridge. He has sued the university, claiming that he was fired because of his religious views. This update isn’t about the lawsuit; I have no knowledge of how that is going. Instead, this update is about the fossil itself.

Samples from the fossil were sent to Dr. Alexander Cherkinsky at the University of Georgia’s Center for Applied Isotope Studies for dating via the carbon-14 dating method. Since the current half-life of carbon-14 is “only” about 5,700 years, there should be no detectable levels of it in the original parts of the fossil, if the fossil is millions of years old. However, Dr. Cherkinsky’s lab found very detectable levels of carbon-14. In fact, there was so much carbon-14 in the fossil that it was given a date of 41,010 ± 220 years.2 This is well within the accepted range of carbon-14 dating, and it is actually younger than other carbon-14 dates reported in the scientific literature.3

While this is an interesting result, it is not as interesting as I would like it to be. I wanted the soft tissue that was found in the fossil to be dated, but it was not. Instead, the fossil’s bioapatite (a mineral found in bone) was dated. According to a 2009 report in the journal Radiocarbon, bioapatite is actually preferable to soft tissue in many cases. As the report states:4

Contamination of the organic fraction in the process of the burial or during museum preservation treatment generally prohibits the use of the collagen fraction for dating. Our investigation has shown that the pretreatment of bone with diluted acetic acid following a proscribed technique allows the separation of the bioapatite fraction from diagenetic carbonates.

Please note that “diagenetic carbonates” refer to contaminants that occur during the fossilization process. The report then gives a method by which original bioapatite can be extracted from a fossil. Dr. Cherkinsky’s lab followed that procedure. Since the lab specifically reported a date for the fossil’s bioapatite, I have to assume that the investigators who actually did the preparation and dating think they were dating the fossil’s original bioapatite, not a mixture of bone and contaminants.

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More Archaeological Evidence That Supports The Bible

Posted by jlwile on December 30, 2014

This bulla (a clay seal) and five others were found in a 10th-century BC village near what was the border between Judah and the land of the Philistines.  The ruler in the photo is marked off in centimeters.  (click for credit)

This bulla (a clay seal) and five others were found in a 10th-century BC village near what was the border between Judah and the land of the Philistines. The ruler in the photo is marked off in centimeters. (click for credit)

Back in the late 1980s and the early 1990s, it was fashionable among certain archaeologists to claim that Biblical characters such as King David never existed. However, archaeological finds like the Tel Dan Stele forced most of these archaeologists to admit that King David was, indeed, an actual historical figure.

But many of them still wanted to doubt the accuracy of the Biblical text. As a result, they grudgingly admitted that David really existed, but they claimed that the Old Testament “glorified” him. He wasn’t the king of a mighty kingdom, as depicted in the Bible. Instead, he was more of a tribal chieftain who commanded a rag-tag group of rural villagers. National Geographic, for example, describes how Dr. Israel Finkelstein, an archaeologist at Tel Aviv University, sees it:1

During David’s time, as Finkelstein casts it, Jerusalem was little more than a “hill-country village,” David himself a raggedy upstart akin to Pancho Villa, and his legion of followers more like “500 people with sticks in their hands shouting and cursing and spitting—not the stuff of great armies of chariots described in the text.”

While this might be the fashionable view among certain archaeologists, the actual archaeological evidence speaks strongly against it. As I discussed more than a year ago, the excavations at a large city called Khirbat Qeiyafa have demonstrated that in the late 11th-century BC (David reigned in the early 10th century BC), Judah was already a thriving kingdom. Just recently, more archaeological evidence has surfaced to back up this view of ancient Judah.

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USGS Sacrifices Scientific Integrity to Jump on the Global Warming Bandwagon

Posted by jlwile on December 16, 2014

This aerial photo, captured by Corey Accardo of the NOAA, shows the enormous walrus haul-out.  (photo in the public domain)

This aerial photo, captured by Corey Accardo of the NOAA, shows the enormous walrus haul-out that occurred this year. (photo in the public domain)

The National Geographic headline says it all:

Biggest Walrus Gathering Recorded as Sea Ice Shrinks
More than 35,000 of the marine mammals have congregated in Alaska

Unfortunately, the headline isn’t true. It isn’t the biggest walrus gathering, and it’s not clear such gatherings have any relationship whatsoever to the amount of sea ice that exists in the Arctic. Where did National Geographic get their false information? From the United States Geological Survey (USGS).

The National Geographic article goes on to say:

Scientists have seen large haul-outs on the Russian side of the Bering Strait for quite some time, says Anthony Fischbach, a wildlife biologist at the USGS in Anchorage. But since the first recordings of walrus gatherings in Alaska in the 1870s, groups of this size weren’t observed until 2007, he said.

Of course, that’s also not true. Either the scientists at the USGS didn’t bother to check the literature on what they have been studying, or they willfully ignored the recorded observations of the past. This is not the largest haul-out on record for walruses, and haul-outs of this size have been observed several times in the past.

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Research Shows That We’ve Been Wrong About Stem Cells

Posted by jlwile on December 11, 2014

This is a simple schematic of a tooth. (click for credit)

This is a simple schematic of a tooth. (click for credit)

Stem cells are a hot topic in biology. Scientists call them “undifferentiated,” because they have not yet specialized to become a specific kind of cell. This means that a stem cell can develop into several different kinds of cells, depending on what the body needs. For example, everyone has stem cells in their bone marrow. Some of those cells (called hemopoietic stem cells) can develop into various kinds of blood cells, while others (called stromal stem cells) can develop into fat cells, bone cells, or cartilage cells. Physicians have used such stem cells to treat certain heart conditions1, and it is expected that as time goes on, more stem-cell-based treatments will be developed.

Of course, bone marrow isn’t the only place in which stem cells reside. In fact, stromal stem cells can also be found in tooth pulp, the soft tissue that is under the tooth’s dentin (see the illustration above). That’s where the blood vessels and nerves of the tooth are found. While scientists have known for a long time that these stem cells are there, how they get there has always been a mystery.

Nina Kaukua and her colleagues weren’t trying to solve that mystery. They were just studying certain kinds of cells in the teeth of mice. These cells, called “glial cells,” are support cells that help the nerve cells (called neurons) do their job. In their research, they were adding a fluorescent chemical to these cells and watching what happened to them over time. What they found was kind of shocking!

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What Does It Mean To Be Open-Minded?

Posted by jlwile on December 2, 2014

My new elementary science series has been included in Cathy Duffy's "102 Top Picks for Homeschool Curriculum"

My new elementary science series has been included in Cathy Duffy’s “102 Top Picks for Homeschool Curriculum”

Those who have been homeschooling for many years probably recognize the name Cathy Duffy. For years, her Christian Home Educators’ Curriculum Manual was the main reference homeschooling parents used to choose among their various curriculum options. Over the years, other means by which home educators can get curriculum advice have been developed. Nevertheless, Cathy Duffy continues to be a trusted resource for many homeschooling parents.

Her latest book, 102 Top Picks for Homeschool Curriculum, is a set of reviews of what she considers to be the best curriculum available to home educating parents. I was honored to find out that my new elementary science series has been included in that book. In her review, she writes:

I’m not aware of any other science curriculum similar to this. While it is a Christian curriculum, it avoids the apologetics flavor of some others that spend a lot of energy arguing for creationism and against evolution. Nevertheless, it helps students view science from Christian worldview. The use of hands-on activities to introduce lessons, the multi-age format, and the chronological approach in this series are also features likely to appeal to many families. This seems to me an excellent way to teach science, and an approach that should have exceptional appeal for classical educators.

I truly appreciate Cathy Duffy’s kind words!

Of course, there are many other reviews of my new series, and most of them are very positive (see here, here, here, here, here, and here, for example). There is one negative review as well. In addition, there is one review that is a bit mixed, and it’s the one that caused me to write this post.

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More Than A Marksman

Posted by jlwile on November 4, 2014

An archerfish hunting a cricket (click for video)

An archerfish hunting a cricket (click for video)

I have been intrigued by archerfish (genus Toxotes) ever since I saw them at an aquarium. They like to feed on insects that crawl around on the plants near the water’s edge. When an archerfish spies an appetizing insect, the fish shoots a stream of water out of its mouth, hitting the insect and knocking it into the water. The fish then goes to the surface and swallows the insect. You can watch a video of this happening by clicking on the picture. Youtube has several other videos of these incredible fish.

Obviously, the archerfish has to “know” a lot of physics to be able to hunt the way it does. After all, as soon as the water leaves its mouth, it is affected by gravity. As a result, the stream of water doesn’t travel straight to its target. Its path bends downward, forming a shape called a parabola. Because of this, the archerfish can’t aim directly at its prey. Instead, it has to aim above its prey, taking the curved shape of the water’s path into account.

But that’s not the end of the story. When light passes from one medium to another, it bends in a process called refraction. This causes a problem for what we see when we look at things that are in the water. Consider, for example, looking at a fish that is swimming in a pond. You see the fish because light hits the fish, reflects off the fish, and travels to your eyes. However, when the light passes from water into air, it bends, and that causes a problem for you. Look at the drawing below:

refraction

The light coming from the fish bends when it enters the air, but your brain interprets light as traveling in a straight line. So when your brain constructs the image of the fish, it doesn’t take refraction into account, and therefore it forms the image of the fish at a shallower depth and behind where the fish actually is. Those who try to spear fish while standing in shallow water have to account for this. If they don’t aim their spear in front of the place where they see the fish, they will never hit it.

The archerfish, of course, has a similar problem. The light that its eyes receive bends when it hits the water. Because of the way it bends, the fish sees the insect closer and lower than it really is. So not only does the archerfish have to account for the effects of gravity when it aims its water stream, it also has to realize that it shouldn’t aim for the position where it sees the insect. Instead, it should aim for a position that is closer and lower!

If all that isn’t impressive enough, scientists have recently found out that the archerfish uses even more physics when it hunts!

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Bill Nye Makes a Prediction

Posted by jlwile on October 8, 2014

Bill Nye is known as "The Science Guy," even though some of his behavior is rather anti-science. (click for credit)

Bill Nye is known as “The Science Guy,” even though some of his behavior is rather anti-science.
(click for credit)

Despite the fact that Bill Nye is known as “The Science Guy,” some of his behavior is rather anti-science. He doesn’t think certain scientific ideas should be debated, despite the fact that conflict between competing theories is one of the most important aspects of science. He also narrated a faked experiment, demonstrating his lack of understanding of basic climate science along the way. Nevertheless, he is an interesting (and funny) guy. In addition, he debated Ken Ham on the creation/evolution issue. Even though the debate was not all that interesting, it was nice to see him engage in it. That’s more than most evolutionists will do! As a result, I like to keep up on what Bill Nye is doing and saying.

He was recently in Canada to attend the 65th International Astronautical Congress. While there, he was interviewed on The Morning Show. You can see the entire interview here. Not surprisingly, I disagreed with much of what he had to say, but I want to highlight two of his statements here. The first is a prediction. When speaking of creationists, Nye said:

In another 20 years, I claim, those guys will be just about out of business. That’s my claim.

I am willing to make exactly the opposite claim. I predict that in 20 years, creationism will be stronger than ever. I expect more scientists will be creationists, creationism will be more openly discussed in academic settings, and there will be more groups dedicated to communicating creationism to the general public. This will be true not only for the U.S., but for most countries in the world. After all, contrary to a previous statement Bill Nye made, creationism isn’t something unique to the U.S.

Barring some unforseen tragedy, Mr. Nye and myself should both be alive in 20 years. It will be interesting to see whose prediction is the more accurate one.

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Climate Science Is Not “Settled”

Posted by jlwile on October 3, 2014

Neither how the globe is warming nor how much humans are responsible for it is understood.  (click for credit)

Neither how the globe is warming nor how much humans are responsible for it is understood.
(click for credit)

Unfortunately, because of the college class I am teaching, a looming publishing deadline, and an upcoming speaking engagement in South Africa, I don’t have time to write a full blog article. However, a man I respect and admire sent me a link to a Wall Street Journal article about climate change. The Author is Dr. Steven E. Koonin, a theoretical physicist and member of the National Academy of Sciences. The article is an excellent example of how to approach the issue of climate change from a truly scientific perspective. Unfortunately, you rarely find such an approach in most discussions of the subject. In my opinion, here is the best point he makes:

Policy makers and the public may wish for the comfort of certainty in their climate science. But I fear that rigidly promulgating the idea that climate science is “settled” (or is a “hoax”) demeans and chills the scientific enterprise, retarding its progress in these important matters. Uncertainty is a prime mover and motivator of science and must be faced head-on. It should not be confined to hushed sidebar conversations at academic conferences.

I couldn’t agree more!

Neil deGrasse Tyson – Serial Spreader of Falsehoods

Posted by jlwile on September 18, 2014

Neil deGrasse Tyson speaking as host at the Apollo 40th anniversary celebration held at the National Air and Space Museum. (click for credit)

Neil deGrasse Tyson speaking as host at the Apollo 40th anniversary celebration held at the National Air and Space Museum. (click for credit)

A few months ago, I discussed some of the many historical falsehoods spread by Fox’s reboot of the television show known as Cosmos. A professor of history, philosophy, and sociology of science at Michigan State University actually wondered if it was okay for the show to promote such falsehoods, because the ultimate goal was to get people to believe in a naturalistic view of the universe. According to him, this is a good thing, so perhaps it’s okay to lie a bit about history in order to achieve that goal.

At the time, I didn’t want to blame the show’s host, Dr. Neil deGrasse Tyson, for these falsehoods. He’s a very likeable guy, and besides, he’s an astrophysicist, not a historian. I assumed that he was just reading a script and didn’t know enough to realize that the script was wrong. After all, Bill Nye had a similar problem when he didn’t understand the science behind a faked experiment that he narrated. Unfortunately, I think I was giving Dr. Tyson too much credit.

Thanks to the folks over at Evolution News and Views, I was made aware of three articles at The Federalist which show that spreading falsehoods seems to be a pattern for Dr. Tyson. The first article discusses how he made up a fake newspaper headline, and in the process, demonstrated that he doesn’t understand basic statistics. The second article rehashes the first one and then gives an example of a quote Dr. Tyson fabricated as well as a supposedly true story he tells, the details of which seem to change as he tells it. The third article discusses another fabricated quote that demonstrates Tyson’s lack of Biblical knowledge.

There is simply no excuse for making up quotes, headlines, and supposedly true stories. Now that I have read these articles in The Federalist, I wonder if Dr. Tyson had a hand in writing the historical falsehoods he spewed on Cosmos. It seems that would be in keeping with his standard mode of operation.