Anthropology.net

If you look at the time stamp of both Bora‘s and Greg Laden‘s posts, you’d notice that they just broke the embargo on a new study of a prehistoric case of tuberculosis that was supposed to go live at 5pm PST, 8pm EST. Now that the news is out, albeit slightly earlier than expected, I figure I should also cover it. The press release touts that the human remains from a site called Atlit-Yam in Israel have provided genetic evidence for the earliest known cases of tuberculosis, dated at 9,000 years old.

Atlit-Yam, Israel

Atlit-Yam is a site currently submerged 8 to 12 meters below sea level in the North Bay of Atlit. The site is about 10 kilometers south of Haifa. Previous researchers have radiocarbon dated the site to be 9,250 to 8,160 years old. The site has yielded both floral and faunal remains along with tools. The floral remains and the faunal remains indicate that these people already made the transition from hunter gatherer subsistence to a fully Neolithic lifestyle.

Human remains were also recovered from the site, and some show characteristic bone lesions that are signs of tuberculosis, specifically the remains of a 25 year old woman buried with an infant. The age of the woman was estimated based on dental attrition, epiphyseal ring ankylosis and the symphysis of the pubis, which are all pretty solid markers. The bones were preserved in a muddy dark clay substance, an anaerobic condition which is very conducive for DNA preservation. Even though other elements have tuberculosis caused lesions, the researchers specifically analyzed the ribs and arm bones of the female adult and long bones of the infant.

Paleopathological lesions on Neolithic infant bones.

Because of the excellent conditions for DNA preservation, the authors moved ahead with two molecular techniques to determine if tuberculosis was the causative agent of the lesions. First they deployed a PCR experiment, specifically designing a primer set to the fish out Mycobacterium tuberculosis sequences. Secondly, they utilized a reverse phase high performance liquid chromatography (HPLC) method that tried to isolate mycobacterial cell wall mycolic acids from the sample.

The PCR yielded positive results with the multi-copy IS6110 & IS1081 fragments, obtained from the rib of the woman and infant long bone. The fragments were confirmed to be valid by sequencing. These fragments are restriction fragment length polymorphisms and are commonly used as definitive signatures of Mycobacterium tuberculosis. The authors compared their PCR fragment sequences to Genbank and also reported that the sequences are identical to those in the NCBI database for M. tuberculosis.

The HPLC also provided evidence that there are mycobacterial cell wall molecules present in the samples. The woman had the highest amount per mg of bone, at 20.14 pg, while the infant had a smaller amount at 0.12 pg/mg. Nonetheless, both lines of evidence along with the visual lesions show that at least two of the people of Atlit-Yam had a tuberculosis problem.

As I mentioned, it seems that the press is going to love the ‘earliest evidence of TB’ sound bit. But it’s not particularly true because, John Kappelman announced the discovery of tuberculosis in a 500,000 year old Homo erectus cranial fragment last yet. I have my doubts about the H. erectus diagnosis though. The authors also did review other paleo-tuberculosis cases such as the 17,000 year old bison and the 4,000 year old Egyptian human bone and soft tissue sample. Either way, this is the earliest report of the disease in humans that has been confirmed by molecular means.

One last thing, Atlit-Yam is among the very few Pre-Pottery Neolithic sites where domesticated cattle have been found. Tuberculosis in humans was thought to have a zoonotic origin, perhaps transmitted to humans from domesticated cattle during the Neolithic revolution. But that theory has been on the rocks, and these individuals were clearly infected with Mycobacterium tuberculosis, not Mycobacterium bovi, which infects cattle. Could the cattle have caused the tuberculosis in these two individuals? What do you think?

Israel Hershkovitz, Helen D. Donoghue, David E. Minnikin, Gurdyal S. Besra, Oona Y-C. Lee, Angela M. Gernaey, Ehud Galili, Vered Eshed, Charles L. Greenblatt, Eshetu Lemma, Gila Kahila Bar-Gal, Mark Spigelman, Niyaz Ahmed (2008). Detection and Molecular Characterization of 9000-Year-Old Mycobacterium tuberculosis from a Neolithic Settlement in the Eastern Mediterranean PLoS ONE, 3 (10) DOI: 10.1371/journal.pone.0003426

I remember reading a short announcement in 2003 about the discovery of 385,000–325,000 years old human-like footprints near the Roccamonfina volcanoes in southern Italy. We haven’t found many paleo-footprints, so any discovery is welcomed with excitement and of course with controversy. Some of the most notable paleo-footprints are the 3.5 million year old prints from the Laetoli ash bed in Tanzania (which are in danger of being destroyed), the Pleistocene footprints from Langebaan, South Africa and another set from the same era from Willandra Lakes, Australia. There’s also the highly curious 40,000 year old Toloquilla footprints in Mexico.

Photos of the Devil's Footprints from Roccamonfina Volcano (Source: 10.1038/422133a)

The three sets of prints from Roccamonfina show that these individuals were fully bipedal and were navigating a steep descent. The tracks have some sharp hairpin turns, indicating at times they were negotiating some precarious moments. There’s even evidence of slipping, an occasional hand print shows up from time to time, suggesting someone wiped out a couple times.

The authors also measured the dimensions of the tracks and estimated that the individuals who made them were no taller than 1.5 meters in height, or 4 feet 11 inches. Again, they were fully bipedal but didn’t have a completely modern human gait. The authors were careful and didn’t get into a discussion about exactly which archaic Homo species made these tracks. At this time in Europe Homo heidelbergensis is thought to be the dominant species. The authors were also cautious and warned that the dating of the volcanic tuffs that the trackways were made on are provisional and preliminary.

I haven’t read anything about the footprints until yesterday, when I saw that Dienekes shared a citation to this new paper, “Oldest human footprints dated by Ar/Ar.” The authors of the new paper criticize that the previous authors relied on an old and imprecise K–Ar date. They instead decided to do a detailed ⁴⁰Ar/³⁹Ar dating from a sample collected directly from the footprint-bearing layer (about 5 meters away, actually). A whole range of dates were ultimately calculated, from 332,000 ± 5,000 to 403,000 ± 5,000 years ago, but a tightly grouped peak of dates clustered around 340–348,000 years ago. The authors calculated the best fit a Gaussian distribution centered at 344.5 ± 5,600 years ago.

With this slightly more refined date, we now know that the footprints were made awfully close to the Climatic Termination IV, a time at which the global ecosystem was making transition between a glacial maximum and the sudden establishment of warmer conditions…. Providing us a window into several minutes of archaic human activity during a shift in ecological and paleoclimatic conditions of the Middle Pleistocene.

Paolo Mietto, Marco Avanzini, Giuseppe Rolandi (2003). Palaeontology: Human footprints in Pleistocene volcanic ash Nature, 422 (6928), 133-133 DOI: 10.1038/422133a

S SCAILLET, G VITASCAILLET, H GUILLOU (2008). Oldest human footprints dated by Ar/Ar Earth and Planetary Science Letters DOI: 10.1016/j.epsl.2008.08.026