Last month we reported on the first people who, around twelve thousand years ago, were lining their loved ones’ graves with flowers. This month, we have a piece on the “extinct” frog that was “resurrected” and then discovered to be a living fossil.
Both of these studies were led by Israeli researchers from other institutions. The Weizmann contributions were what you might call technical: precise radiocarbon dating and x-ray micro-tomography. While the findings, themselves, were publicized in many scientific and popular publications, the technological advances that make these findings possible tended to get ignored. (I mean, radiocarbon dating – that’s been around for years, right?)
So, I would like to take a moment to sing the praises not just of the new and improved technologies, but of the people who use them daily to produce scientific results. I am talking about people who are constantly looking to stretch the limits of their equipment, to perfect the measurements or images, and who excel at translating a scientific question into a research technique. It is pretty safe to say that most research would not get done without them.
Radiocarbon dating has, indeed, been around for a while, but not in the way that Dr. Elisabetta Boaretto practices it. She begins in the field, getting down into the dirt and dust to choose the samples for dating so that, on the one hand, she has the bits of material most likely to yield good dates and, on the other, she can double-check the stratigraphy.
Boaretto and her team are now in the process of inaugurating a new piece of machinery – a large accelerator mass spectrometer – that promises to take things to even higher levels. If the older techniques assess the ratio of the stable C-13 to the radioactive isotope C-14, the new accelerator counts individual atoms. That means that precise dating can be achieved from a single seed, or that a small handful of microscopic phytoliths – silica remnants of ancient plant matter – can be dated from the minuscule amounts of carbon still inside them. The precision of the dating will take some of the guesswork out of the archaeology. For example, if you know there was a drought in a particular area over a certain time period and you know that area was inhabited up to that time – give or take a few hundred years – you might assume that the drought was responsible for the end of the site’s occupancy. But if you can pinpoint the abandonment to a decade or so around 200 years before the drought, as Boaretto has recently done, you have not only produced a much more precise date, you will have challenged a basic assumption about environmental causes and the downfall of cultures.
It is this attention to detail, innovation in technique and adept use of the equipment, even more than the equipment itself, which has led the prestigious Max Planck Institute for Evolutionary Anthropology to collaborate with the Weizmann Institute in setting up a joint research center.
Down in the basement of the research services building, Dr. Vlad Brumfeld works his magic with the x-ray micro-tomography machinery. And I do mean magic: The finely detailed 3-D image of a frog’s skeleton is as beautiful and as poignant as a Georgia O’Keefe painting. The recent findings that the Hula painted frog is the last living remnant of an otherwise extinct genus was the result of an interesting convergence. Brumfeld had first begun examining a preserved specimen held in the Hebrew University’s natural science collection. The frog – distinguished by being the first amphibian to have been declared extinct by the IUCN – had not been seen alive since the 1950s. Around that time, some persistent frog lovers rediscovered the Hula painted frog hiding in the swamps, giving researchers additional specimens (that had died a natural death) to investigate.
Again, innovation helped crack the case: Brumfeld and a student had figured out a way to prepare the specimen for imaging by saturating it in vapor, rather than immersing it in liquid, to avoid distorting the image. It was the structure of the frog’s skull, along with DNA testing, that clued the research team into its true place in the frog family.
Frog skeleton structure, by the way, is just one of the wonders that are investigated in the x-ray micro-tomography lab. Brumfeld reports working with Institute scientists to reveal the internal structure of developing bone, the microstructure of the soft tissue inside teeth, soil infiltration, tiny defects in diamonds, particles of minerals and silica in plant tissues, the shape of micromachinery tools and more.