Sunday, March 30, 2008

Oldest Pre-Human Ancestors in Europe

According to the cover story in Nature this week, a jawbone discovered in a cave in Spain pushes back the date of arrival of pre-human hominids in Western Europe to 1.1 million years. The jawbone belonged to a pre-human ancestor called Homo antecessor who lived approximately 300,000 years before the previous earliest-known pre-human in Western Europe. Artifacts at the site indicate that Homo antecessor fashioned crude tools and used them to butcher small animals.

We don’t mention Homo antecessor in Human Biology, 5th ed. so that the beginning student is not baffled by the number of pre-human hominid names that have cropped up in recent years. Until more fossils are discovered, it might be best to lump Homo antecessor with other better-known European archaic humans such as Homo heidelbergensis.

Reference: “The First Hominin of Europe”. Nature 452: 465-469, March 27, 2008.

Monday, March 17, 2008

A REALLY Costly Drug

A drug called Cerezyme has become a topic of debate among health care professionals, insurance companies, and patients. That’s because at the recommended dosage, the drug costs up to $300,000 a year.

Cerezyme is used to treat a rare inherited disorder called Gaucher disease, characterized by severe deterioration of bones and joints. The recommended dosage was determined on the basis of a clinical trial in only twelve patients more than 20 years ago. At the recommended dosage the drug has proven to be quite effective. But would a lower dose work just as well? Many doctors and insurance companies think so, but the manufacturer (Genzyme) has no interest in finding out. And why would they, when the drug has annual sales of over a billion dollars? Genzyme says it’s not their issue; they’d leave it up to doctors to determine whether a lesser dose would work just as well in their patients.

If the drug were cheap, dosage wouldn’t be an issue. But insurance companies are paying for this drug, and therefore so are we, indirectly. Who do you think should be responsible for determining the proper dose?

Thursday, March 13, 2008

Do Identical Twins Have Identical DNA?

It has long been thought that identical twins must have identical DNA, since they came from the same fertilized egg. The usual explanation for any observed differences between identical twins was that they were caused by environmental factors such as diet, exercise, or exposure to chemicals.

Now we know that the DNA of identical twins is not always identical. That's because as cells divide over and over again during normal human growth and development, some sections of the DNA are omitted accidentally once in awhile. Other sections of the DNA are duplicated unnecessarily. The result is that some somatic cells and even tissues and whole organs may have one to three copies of some genes, instead of the usual two. Such copy number variations occur rarely in all people, not just in identical twins.

It would be helpful to know whether copy number variations contribute to specific human diseases, and (out of curiosity) whether copy number variations contribute to the slightly different phenotypes of some "identical" twins.

Monday, March 10, 2008

Inhaled Insulin (Who Cares?)

Eli Lilly & Company announced that it was halting development of its inhaled insulin product because it no longer believes that the product has sufficient market potential. The company recorded a three-month loss of $90–120 million to shut down the failed project. The announcement comes just five months after the first inhaled insulin product, Pfizer’s Exubera, was pulled from the market because of weak sales.

What happened? For decades, scientists and drug marketers dreamed of blockbuster profits from the first inhalable insulin product that would eliminate the need for injections in the treatment of diabetes. It turns out that no one cared. Patients didn’t like the cumbersome device used to administer the powdered insulin, and doctors found that the powders had a slight tendency to impair lung function.

It seemed like such a good idea.

Saturday, March 8, 2008

Hormone Replacement Therapy Revisited

Back in the 1990s the federal government launched the Women’s Health Initiative to investigate the health of older women. One of its goals was to determine the risks and benefits of hormone replacement therapy (HRT) in post-menopausal women. The HRT study was stopped early (in 2002) when it was discovered that HRT led to an increased risk of breast cancer, heart attacks, and strokes.

What about the women who were on HRT during the study - do they remain at higher risk even after discontinuing HRT? The good news is that apparently most of the increased risk goes away with time. The first follow-up study indicates that three years after HRT is discontinued, the increased risk of heart attacks disappears, and the increased risk of cancer declines significantly. Future reports will show whether any increased risk of cancer remains as time passes.

Current recommendations for HRT remain unchanged; women should consider HRT only if they have moderate to severe post-menopausal symptoms, and for the shortest time and lowest dose that is effective.

Monday, March 3, 2008

Global Warming and Science Literacy

If people really understood global warming they’d be more concerned about it, right? Wrong! According to a recent survey, respondents who are more informed about global warming and who have a high confidence in scientists “feel less responsible for global warming, and also show less concern for global warming” (Personal Efficacy, the Information Environment, and Attitudes Toward Global Warming and Climate Change in the United States. Risk Analysis 28:113-1267, 2008).

Why is that? The authors suggest that its because “Global warming is an extreme collective action dilemma, with the actions of one person having a negligible effect in the aggregate.” They suggest that because informed persons understand this, they tend to feel less personally responsible and more pessimistic about their ability as individuals to change the outcome.

Okay, informed persons may feel less responsible, but why are they less concerned? One possible explanation is that people who are informed about science tend to trust that scientists will find a technological solution. After all, we’ve sent men to the moon, discovered antibiotics, and developed computers, haven’t we?

How confident are your students that scientists will find technological solutions to global warming in their lifetimes? Do they see any technological solutions on the horizon?