It seems that there’s a debate over who’s responsible for bringing syphilis to Europe. Some researchers posit that it was brought back from the New World by Christopher Columbus, while others argue that it arose from a non-sexually transmitted strain of bacteria that was present in Europe previous to his voyage.
In this study, researchers examined and compared DNA from 26 different strains of pathogenic Treponema (the genus of bacteria which contains the syphilis-causing organisms). In doing so, they discovered that the strains that cause syphilis are the newest, and that they are most closely related (genetically speaking) to a South American strain. A non-sexually transmitted Old World strain (which would have been present in Europe prior to Columbus’ return from the Americas), is actually the oldest strain, and is indistinguishable from a simian strain of Treponema.
In case anyone was wondering, this is the type of stuff I used to do in undergrad, only with plants and snakes instead of venereal diseases. In the case of the plants, we used to actually use the amount of genetic variation over time as a way to date the divergence of two species (or two families, or whatever). With the snakes, we used the relationships of different species on different Caribbean islands to determine how those islands were speciated – either from one island breaking into two, or whether the relationships mirrored ocean current and wind patterns, which indicated that the snakes had gotten to those islands by floating across from other islands.
Which reminds me – I think I still have two papers coming out at some point from that lab. At least I hope they’ll actually be published, as opposed to languishing on my advisor’s desk…
Also, it looks like he set up an online database of divergence times recently, so if you’re dying to know the time of divergence for dogs and cats, have a go at it (Spoiler – it’s between 50 and 60 million years ago).
And that folks, is your random science lesson of the day.