So I’ve been extremely busy the last few weeks trying to get everything wrapped by the deadlines that always come with the end of the semester. I just completed working on a paper for Molecular Biology about cystic fibrosis. Before I go any further, let me define just a few genetic concepts using the analogy of shoes, so that I don’t have to worry about readers being completely lost. Thirty seconds of biology won’t kill you, I promise.

• allele – alternative version of gene. If shoes are a gene, then cowboy boots, sandals, and tennis shoes would be alleles. For any given gene, you’ve got two alleles – one from mom and one from dad.
• homozygous – you’ve got the same two alleles for a given gene. You’re wearing matching tennis shoes.
  • homozygous dominant – both of your alleles make the same working protein. You’re wearing matching tennis shoes.
  • homozygous recessive – both of your alleles either don’t make a protein or make a protein that doesn’t work. You’re not wearing any shoes and have two bare feet.
• heterozygous – you’ve got different alleles for a given gene. You’re wearing one cowboy boot and one sandal, or one cowboy boot and one bare foot.

Cystic fibrosis is a homozygous recessive trait. You’ve got to get two CF alleles that don’t work right to get the disease.

Enough of the background information. I was focusing on one thing in particular. The allele that causes CF is a lot more common in European populations than one might expect for such a seemingly detrimental allele. In fact in Caucasian populations, the frequency of carriers can reach as high as 1 in 25 people! That’s pretty darn high when you consider that if two copies of those alleles end up in a child, that child’s dead before they’re three years old. How do you explain that? The likely explanation is what’s called heterozygous advantage, where heterozygous are better fit for their environment than homozygotes.

The classic example of this is sickle-cell anemia and malaria. It turns out that heterozygotes are much less likely to get malaria than homozygotes. I was looking on the internet for a reference to the scientific literature that discusses heterozygous advantage with sickle-cell anemia, when I came across this page from the website of a medical doctor at Harvard. (Incidentally, it’s a nice lengthy discussion if you want to learn more about natural selection favoring a detrimental allele through heterozygous advantage.) But it contained one little illustration that immediately caught my eye and made me laugh out loud.

Figure 2. Schematic representation of the effect of the sickle cell hemoglobin gene on survival in endemic malarial areas. People with normal hemoglobin (left of the diagram) are susceptible to death from malaria. People with sickle cell disease (right of the diagram) are susceptible to death from the complications of sickle cell disease. People with sickle cell trait, who have one gene for hemoglobin A and one gene for hemoglobin S, have a greater chance of surviving malaria and do not suffer adverse consequences from the hemoglobin S gene.

Oh, okay. I get it. But still, it’s a rather odd and comical choice for the illustration. It tickled my funny bone so much that I had to share.

So getting back to cystic fibrosis, the main evidence for heterozygous advantage comes from a study1 which showed that the bacteria which cause typhoid fever use the protein that the cystic fibrosis gene creates. Thus, if you’re heterozygous (one good copy, one bad) then you have less of that protein on the surface of your cells lining your digestive tract. Using mice as a model, they showed that typhoid bacteria are 86% less successful at infecting cells of heterozygotes. They also showed that mice containing two bad copies of the CF gene were not infected by any typhoid bacteria. Thus typhoid are using that protein as their entries into the cell.

As typhoid is a disease that has ravaged Europe for many years in premodern time, it now becomes understandable why selection would increase the frequency of the CF allele in European populations.

It’s been too long, hasn’t it? I’ve got friends asking me to write again, friends that are hilariously cajoling me into writing again, and absolute nutjobs that leave the craziest comments on old posts.

This latter comment is especially hilarious for it’s illiterate ramblings against evolution, repetition of the belief that no one is required to pay income taxes, and then a sudden divergence into the necessity of vitamins and seed eating to prevent cancer. The list of seeds we should eat are apple, peach, and apricot seeds, which as any good biologist can tell you are filled with cyanide. If you’re skipping the fruit and going straight for the seeds, it doesn’t take but a handful at once to provide a lethal dose. But hey, you don’t get cancer! I especially liked the National Cancer Institute’s description of a drug name Laetrile based on these seed products. “Laetrile has shown little anticancer effect in laboratory studies, animal studies, or human studies. The side effects of laetrile are like the symptoms of cyanide poisoning.”

Yes, it’s been too long since I’ve blogged.

Why did I stop blogging?

The short and sweet answer is that I suddenly got tired of it. It felt more like a chore than it did fun. As the amount of time I poured into school skyrocketed (and so did the amount of writing for school), it was hard to enjoy blogging.

I’m also completely done with these eternal debates about evolution and creationism. At least online anyway. Like the above comments shows, the number of people who froth at the mouth and show up to leave comments far outweighs those interested in learning how science works. We live in the age of Google. In 30 seconds you can get more information about a subject than you can read in 30 days. An understanding of evolution and how it works is not lacking because of a lack of information. Therefore, I’m much more interested in having real conversions with people, face to face, who actually want to learn how things work, not just argue. The time I’ve spent at church talking with people about it on a number of occasions is just so much more fulfilling than blogging about it.

I also face the problem of being a fairly good but extremely slow writer. One story in particular illustrates this better than anything. Not long after we got married, my wife was working on this very lengthy paper for a class. She called me in to ask for help with wording a single sentence. I spent 30 minutes and finally came up with wording that we both liked. So out of 10 pages, I wrote one sentence. When she got the paper back (with a good grade of course), the professor had underline that single sentence and written in the margins, “Nicely worded!” (I’ll smile about that for the rest of my life). But the problem you see is that I can’t spend that long writing a post to Ocellated. There’s not enough hours in the day.

So What Comes Next?

I didn’t want to post again until I really knew what I wanted to say. I think where I am right now is that I would love to post about science. There’s just too many cool little things that I learn to not share them with anyone. And I have fun whenever I can taking pictures, so there’s no better medium than the web for sharing the fruits of that labor.

I promise nothing. I certainly won’t be posting every day. Maybe once a week. Maybe once a month. We’ll just have to see how it goes. But I’d definitely like to get back to talking about science, birds in particular, and I’ve got a few papers that are worth sharing due to their general “cool factor.”

I can’t just leave you with nothing

So for all three of you still checking the blog, I’ll leave you with a few pictures. I have been busy working at photography when I have the time, and I’ve posted many of these quite some time ago, but never wrote a post announcing them. Here’s a list of the recent galleries. Some of the pictures are of course better than others.

• San Antonio Lakes, 12-27-06
• Marfa, TX 12-18 to 12-19-06
• Christmas Bird Counts 2006
• San Angelo State Park, 12-8 to 12-10-06
• OH Ivie Reservoir, 12-2-06
• Forth Worth Nature Center, 11-25-06
• San Angelo Birding, Nov. 2006
• S Tx Birding Festival 2006
• Davis Mountains and Lake Balmorhea, 10-2006

The trip to Marfa, TX (which is in deep southwest TX north of Big Bend National Park, was probably one of the most enjoyable though. I managed to get a couple of incredible pictures of a juvenile Red-tailed Hawk.

There’s more in that album too. And speaking of pictures, I’ve got lots more to process from recent trips which I’ll be posting shortly.

A study reported by National Geographic News places the U.S. near the very end of a shameful list.

Yes, only Turkey rejects evolution more than the United States.

The reasons are what you’d expect — religion — but even I was surprised by the low percentage. Only 14% of U.S. adults thought that evolution was “definitely true.” Oh, I could rant and rave about the way evolution is a theory with every bit as much footing as our other theories in science. I could point out that science seeks truth with a lower case t, not ultimate meaning. I could point out the utility of science, and that the 86% of U.S. evolution rejectors already turn to evolution when they seek medical care, and that in our lifetimes, our knowledge of evolution and its application to medicine will increasingly deepen. Indeed, the article makes this point for me.

Third, the study found that adults with some understanding of genetics are more likely to have a positive attitude toward evolution.

I could do all these things, but as they say, you can lead a horse to water but you can’t make it drink.

National Geographic also offers a great solution to this problem. An excellent article by David Quammen titled Was Darwin Wrong? which appeared in the print edition of the November 2004 magazine. (Alas, the online version lacks the pretty pictures.)

I also offer my own solution. It’s meager, and perhaps a little incomplete. (I could add more to it while condensing it some to make it tighter). But I like to think it’s not bad. My old article on the basics of evolution. Though I’m but a humble grad student, the U.S. would do well to read it. At least 86 percent of them would.