Keeping Time

[The following was brought to my attention by Jerry Coyne's book, Why Evolution is True.]

Earth is old--about 4.5 billion years old. We know this primarily from radiometric dating of rocks, which is based on the fact that certain elements decay into other elements at a constant rate. We also know that Earth is slowing down in its rotation due to tidal forces exerted by the moon, which is at least one reason that leap seconds are occasionally added to our official time. This observed slowing implies that millions of years ago Earth's rotation was faster with shorter days and more days per year.

But is this all just unwarranted extrapolation into the past? After all, as young-earth creationists like to remind us, none of us was there.

In the early 1960's, paleontologist John Wells published a paper describing his study of fossil coral from several ancient periods. As corals grow, they lay down a skeleton of calcium carbonate with a regularity such that distinct layers can be seen, analogous to tree rings. These layers can be discerned as yearly--or even daily--layers. The geological periods had been dated radiometrically, so the expected number of days per year could be calculated. Wells looked at the growth layers of fossil coral and determined how many daily layers were in each year. Lo and behold, he found that the coral daily layers per year correlated nicely with the astronomically calculated days per year.

This represents just one method of independently checking the reliability of radiometric dating. We may not have been there, but coral were; and dead coral tell tales.

For more information on coral timekeeping, see Can Corals Tell Time?

For a nice explanation of radiometric dating and a response to creationist claims, see Radiometric Dating: A Christian Perspective.

For more information on a number of dating methods see Dating Methods in Science.

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One Way of Getting a Link

S. Faux at Mormon Insights gives his perspective on being a Mormon evolutionist. It's a nice read, and my opinion is in no way biased by the fact that he says nice things about me and my blog.

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Great Primate Fossil; Great Hype

Everyone seems to agree that this 47-million-year-old primate fossil, named Darwinius masillae, is a remarkable find. The preservation is fine enough to reveal the stomach contents and the outline of the fur.

But it's also supposed to be a source of revenue--this may be the first fossil whose publication was accompanied by a press conference, a History Channel film, and a book--and is being hyped (i.e. marketed) as a revolutionary find that's going to change everything about our understanding of primate evolution.

For cooler heads, see here, here, and here.

Bottom line: Neat? Yes. Important? Yes. Revolutionary? Not so much.

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Dinosaurs in the Church News

Via S. Faux at Mormon Insights, I was pleasantly surprised to see that the Church News has an article about BYU's Museum of Paleontology and highlights the work of James Jensen.

Once patrons move past the thrill of peering into a "terrible lizard's" jaws they might be even more surprised to learn the Church-owned school operates one of the largest collections of upper-Jurassic period dinosaur fossils in North America.

I think I detect signs of discomfort, as the article seems to spend a little extra effort to assure readers that everything is on the up-and-up, and it neglects to inform when the Jurassic period was. Further, the article does not give any sense of the results of the research--as though making dinosaur displays represents the sum of the "intellectual curiosity" that drives the museum. Nevertheless, it's nice to see a nod to natural history in the Church News.

Note: I've previously written about the North American Museum of Ancient Life, at Thanksgiving Point, which is also based on the work of Dr. Jensen.

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Vital Force Discovered?

This week I was on an airplane, absent-mindedly browsing the SkyMall magazine, when I noticed an amazing device. It's called Aculife, and it is a variation--well, technically a complete re-definition--of acupuncture. It stimulates and helps to unblock qi by delivering mild electrical pulses. But it doesn't just stimulate qi, it can detect it and let you know where the blockages are! I repeat, it can measure qi! That proves that qi exists!

(Click image to enlarge.)

A number of things about the ad caught my attention.

1. It includes a handy (pun) diagram of qi points on the hand. This represents a mixing of pseudosciences. My understanding is that traditional qi points are located all over the body. For convenience, it looks like they've mixed reflexology (which maps the whole body onto the hand or foot) with acupuncture.

2. The map itself is interesting. The heart, liver, and kidneys are depicted in multiple places. And for some reason, the anus is out on the tip of the thumb (?!), along with fatigue, bronchitis, and insomnia--nowhere near the intestines, inflamed colon, diarrhea, or hemorrhoids. True, the spine is represented along the side of the thumb, but it's in the opposite orientation to the anus that you would expect.

3. "The best way to find out if Aculife is right for you and your health is to try it."

4. ...except if you are "pregnant, have a pacemaker, or suffer from malignant tumors, excessive bleeding or tuberculosis." I guess those things have nothing to do with blocked qi.

5. But wait, over at the base of the thumb is "breast tumor." So I guess as long as the tumor is not malignant, it's alright to use Aculife.

6. "FDA Approved" -- Well, okay, that probably just means that the electrical stimulation won't hurt you, not that this actually can be used to diagnose and treat disease.

7. "Diagnose and heal yourself and your family." Oh.

In summary, this is total garbage and if it doesn't technically break any laws governing advertising or medical claims, it should.

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What Separates Humans from Orangutans?

[This post is part of a series, What Separates Humans from the Animals?]

Glucocerebrosidase (GBA) is an enzyme that helps break down a fatty molecule that is present in the cell membrane. Mutations that disrupt its function result in Gaucher's disease, which can have a variety of symptoms with varying severity. An estimated 10-20% of disease-causing mutations are due to the fact that the GBA gene has a duplicate but broken copy next to it. In such cases, recombination between the normal GBA gene and its neighboring pseudogene results in the loss of a fully functional gene, leading to disease.

Wafaei and Choy looked at the GBA genes of several primate species, and it should come as no surprise that chimpanzees and gorillas also have one functional GBA gene and a neighboring pseudogene. I've drawn the following figure to represent their findings. (Note: pseudogenes are sometimes indicated by the Greek letter psi.)

(Click image to enlarge.)

Interestingly, orangutans appear to have two functional copies of GBA, while squirrel monkeys (a New World monkey) have a single GBA gene. The pseudogene is not found in non-primates, including mice, rats, and chickens, either. This suggests that a gene duplication event occured sometime after the lineages leading to squirrel monkeys and orangutans (and other apes) diverged.

The pseudogenes shared by humans, chimpanzees, and gorillas are not exactly the same. Each has some unique mutations that are not shared by the others. However, they all have at least one mutation in common: all three have a 55 base pair deletion in the same place, which appears to be the primary cause for the gene being broken. This is shown in a portion of Figure 4, which is an alignment of part of the various GBA genes and pseudogenes.

(Click image to enlarge.)

The human GBA sequence is at the top and is used as a reference. In the comparison sequences, differences are indicated by the changed letter. If the sequence is the same, it is indicated with a period. Missing sequences are represented with dashes. I've boxed the dashes, which are only in the pseudogene sequences.

This is like three copies of text missing the same run of 55 letters, and suggests that the deletion occurred in a common ancestor rather than three times independently. Unlike us, it appears that Orangutans are unlikely to get Gaucher's disease.

Reference:

Wafaei JR, Choy FY. Glucocerebrosidase recombinant allele: molecular evolution of the glucocerebrosidase gene and pseudogene in primates. Blood Cells Mol Dis. 2005 Sep-Oct;35(2):277-85. (Subscription Required)

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