Thursday, February 12, 2009

The New York Times on Nishtaneh HaTeva

In the New York Times article to which I linked in the previous post, it says the following:
Researchers have long known that bacteria evolve to evade antibiotics, and that parasites, like those that cause malaria, adapt to drugs used against the disease. More recently, researchers have reported that cod, overfished for decades off New England and the Canadian Maritime Provinces, have begun reproducing at younger ages and smaller sizes. Other scientists have reported similar changes in species as diverse as bighorn sheep, caribou and ginseng plants.

This instantly made me think of the concept of nishtaneh hateva, "nature has changed," an approach that was introduced in the medieval period to account for disparities between the Talmud and the natural world as perceived in that era. This was that the physical nature of the world had changed since the time of the Sages. While this approach has been grossly overextended, its original application is to the case described by the New York Times.
The primary source for this concept stems from a ruling in the Talmud relating to the age at which cattle and donkeys can bear young. Establishing this age is important because a firstborn animal of these species automatically belongs to a Kohen; thus, when purchasing an animal from a non-Jew, one must ascertain if the animal could have given birth already. If not, then when the animal gives birth, the calf must be given to a Kohen. The Talmud rules that if they are three years old, then when they give birth, their first offspring definitely belongs to the Kohen. Tosafos notes that this is contrast to the facts known in his time:
The explanation of this [ruling] is that before they are three years old, they can certainly not have given birth. But this is astonishing – surely we see all the time that two-year-old cows can give birth! One can answer that times have certainly changed from how matters were in earlier generations. (Tosafos to Avodah Zarah 24b s.v. Parah V’chamor)

This is the same as the phenomenon described in the New York Times!


Anonymous said...

What does this say about the increase of teenage pregnancies? :P

Bryce said...

"Researchers have long known that bacteria evolve to evade antibiotics, and that parasites, like those that cause malaria, adapt to drugs used against the disease."

Not a disagreement, but a different angle, comes from Professor Bruce Levin from Emory University:

"It is easy to concoct just-so stories to explain the evolution of a mechanism that, like the SOS response, produces quiescent cells that are refractory to lethal agents. Yet it seems unlikely that ampicillin was the original selective force responsible for the evolution of the induction mechanism observed by Miller and colleagues. A bigger challenge to those in the evolution business is to account for the generation of lower fitness cell types when they do not provide an advantage to the collective, like the persisters of Balaban et al. in the absence of antibiotics. Then again, just like people, bacteria do some seemingly perverse things that are not easy to account for by simple stories of adaptive evolution." -- 1Bruce R. Levin, “Microbiology: Noninherited Resistance to Antibiotics,” Science, Vol 305, Issue 5690, 1578-1579, 10 September 2004, [DOI: 10.1126/science.1103077].