Modern Science Archives : Page 34 of 53 : Proslogion

Coral Can Call for Help

This broad-barred goby is one of the species that responds to a coral's call for help (click for credit)

Anyone who has read this blog for a while knows that I am fascinated by the mutualism that seems to be all over creation. You can seem some of my previous posts about this topic here, here, here, here, and here. I recently came across a study that provides another example of mutualism in one of favorite habitats: a coral reef. As an amateur scuba diver, I spend a lot of time enjoying the wonders of coral reefs, and the more we study their biology, the more amazed I am at the interconnectedness that exists among their inhabitants.

The authors of the study were trying to understand how a very common species of coral, Acropora nasuta, protects itself against the toxic seaweed Chlorodesmis fastigiata. This particular seaweed attempts to take over a coral reef by producing chemicals that harm the coral. The chemicals reduce the coral’s ability to grow and feed, allowing the seaweed to “muscle in” on the coral’s turf. When the seaweed is completely successful, it chokes out the coral, forming a shrubby thicket where the coral once was.

As the authors note, previous studies have already shown that overfished coral reefs are more likely to be taken over by such seaweed, so they wondered if perhaps the fish that live in the coral reefs provide some sort of protection for the coral. They found that certain species of goby (particularly the broad-barred goby, Gobiodon histrio, and the redhead goby, Paragobiodon echinocephalus) do, indeed, protect the coral from the seaweed, but the process by which this happens is rather surprising.

Continue reading “Coral Can Call for Help”

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

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!”

Homing Pigeons May Hear Their Way Home

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!

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

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

human_chimp — 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”

Even Shark Embryos Detect Electric Fields

I have always been fascinated by sharks. In fact, of all the times I have been scuba diving, the dive I remember the most occurred off the coast of South Africa. I went with some marine biologists who had been studying sand tiger sharks (Carcharias taurus). As I initially sunk down into the water, I leveled out just a few feet from the bottom, and as I was checking my gauge to determine my depth, a 2-meter (6-feet) long shark swum right underneath me! We ended up seeing more than a dozen sharks of various sizes on that dive. It was incredible.

One of the things that is fascinating about sharks is the way they hunt. While they use their sense of smell (and to some degree their sense of sight), one of their main hunting techniques involves using their electrical sense. Yes, sharks can sense electrical fields, and they are quite good at it. As a recently published book on sharks says:¹

They can detect the minute electrical currents generated by the nervous systems of prey by using electrical sensors called the ampullae of Lorenzini…These sophisticated sensors are very useful in finding prey buried under the sand.

Interestingly enough, these sophisticated sensors often develop while the shark is still an embryo. Is that just to get the shark ready for hunting its prey when it is fully developed, or could there be some use that the embryo has for sensing electrical fields? It doesn’t need to hunt, so for what purpose could it be using its electrical sensors?

Some Australian scientists decided to investigate this issue, and what they found is fascinating!

Continue reading “Even Shark Embryos Detect Electric Fields”

Sockeye Salmon Use Geomagnetic Details to Guide Them Home

Salmon have an incredible lifecycle. They hatch in freshwater streams, eat and mature a bit, and then they make their way into the ocean. They do most of their growing and maturing in the ocean, and when they are ready to reproduce, they return to the very stream from which they hatched to find a mate and begin the cycle all over again.

A lot of research has been done trying to figure out how the salmon know the way back to the specific stream from which they hatched. Well, each stream has it own mix of soil, rocks, and other environmental elements. As a result, each stream has its own specific mix of chemicals. Most of the data indicate that a salmon remembers the specific chemical makeup of its original stream. Once it gets back to freshwater, then, it starts following a “chemical trail” that will lead it back to the stream from which it hatched.¹

While this is rather impressive, it doesn’t really tell us about the most difficult navigational aspect of the journey. The salmon spends a long time in the ocean growing and maturing. As a result, it often ranges far from the place where it entered the ocean. How does it find its way back to the correct freshwater inlet that will lead to the correct stream? It seems hard to believe that it could follow a “chemical trail” that far! Since we know that salmon are equipped with biological machinery that allows them to sense the earth’s magnetic field, it has been thought for some time that salmon use magnetic guidance to get them to the proper freshwater inlet.²

While that’s a reasonable conclusion based on what we know, there hasn’t been a lot of evidence to back it up. However, a recent study published in Current Biology has begun to remedy that situation.

Continue reading “Sockeye Salmon Use Geomagnetic Details to Guide Them Home”

Even More Impressive DNA Storage

dnastore — DNA can store incredible amounts of information (montage of public domain images)

A few months ago, I wrote an article about a group of scientists who stored a book that contained words, illustrations, and Java script on DNA. It was an amazing technical achievement, and it demonstrated the incredible storage capabilities of this marvelous biomolecule. Well, another team of scientists has gone even further: they stored words, pictures, and audio on DNA!

Yes, the team encoded all 154 of Shakespeare’s sonnets, a photograph of the European Bioinformatics Institute (where the scientists work), and a 26-second audio clip from Martin Luther King’s famous “I have a dream” speech.¹ Also, in a very fitting symbolic gesture, they added the famous James Watson and Francis Crick paper that first revealed the structure of DNA.²

This new achievement was noteworthy for more than just the fact that the scientists stored audio on DNA. While the method that the previous team used to store the book worked well, it was difficult for instruments to retrieve the information from the DNA once it was stored there. Thus, the time it took to retrieve the book from DNA storage was fairly long. The scientists who produced this study used a different method to store the information, which made it much easier for instruments to read it back. As a result, not only was everything retrieved from DNA storage with 100% accuracy, the time it took to get it back was significantly reduced.

Continue reading “Even More Impressive DNA Storage”