This may sound like an exaggeration, but our understanding of evolution has become a life-or-death issue for a number of health workers imprisoned in Libya. In the late 90s, poor hygienic conditions had allowed the spread of HIV and other pathogens among children in a Libyan hospital. A group of six foreign health workers—five Bulgarian nurses and a Palestinian doctor now known as the Tripoli Six—were arrested for knowingly infecting the victims. Following confessions that they claim were induced by torture, the six were convicted and sentenced to execution by firing squad.

The international outcry that followed compelled the Libyan supreme court to order a retrial, and the verdict from that retrial has now been handed down: death again, with a single remaining chance of appeal. Nothing unusual about the slow and sometimes unfair motion of the wheels of justice, right?

In this case, wrong: there is clear scientific evidence that these health workers have not been directly responsible for the infections. It has been made available to the court, which chose to ignore it in handing down this most recent death sentence. Perhaps the disturbing aspect of this evidence, however, is that it is based on standard evolutionary and epidemiological evidence—two fields that have become the target of frequent attacks in the culture wars that are engulfing the US.

The journal Nature has been instrumental in leading the efforts against these charges, providing open access to to editorials and scientific discussion of the HIV strains involved in the infections and the course of the epidemic. They have now published what may be the definitive analysis of the HIV outbreak that resulted in these death sentences.

It turns out that over half the infected children wound up in European hospitals at one point or another, and viral samples were obtained from them. Sequencing of these viruses followed by standard building of an inheritance tree based on common descent reveal that all of the viruses are derived from a single, and typical, ancestral virus. That ancestral virus was a member of the strains active in sub-Saharan Africa, which provides migrant workers to Libya. All statistical tests indicate that the virus was already spreading within the patient population prior to the arrival of the foreign health workers at the hospital. Many of the HIV victims were also infected with Hepatitis C while at the hospital; examination of the phylogeny of this virus indicated that the hospital had at least three independent HepC infections active prior to the arrival of the Tripoli Six. The authors clearly state that these results "suggest that Al-Fateh Hospital had a long-standing infection-control problem."

The verdict is a clear indication that Libya doesn't respect scientific evidence and is more comfortable believing President Gaddafi's allegations that the health workers were part of a plot by the CIA and Mossad. For those of you outraged by this verdict, a collection of contact information for people and organizations that are actively helping or can provide diplomatic pressure is available. I would just add that, whatever country you are in, doing what you can to promote a respect for the strength of scientific evidence can prevent a travesty such as this from happening closer to home.