In other words, the halakhic measurement used to determine how much food must be eaten in order to recite an after-blessing, or the amount of matzo required to eaten at the seder, are much smaller than today's rabbis think -- with one very interesting exception:
First, a brief (and admittedly, weak) report on the new research, from the Jerusalem Post:
...Prof. Mordechai Kislev, who headed the team with Dr. Orit Simhoni, Yonit Tabak and Ofer Tzarfati-Zuta, maintains that Syrian and Nabali strains, whose weight per olive is only around five grams (about a sixth of the weight of a machine-made matza), are the model for the halachic standard. The researchers said these types of olives, smaller than today's olives, were the most common during ancient times.
There are rabbinical arbiters who maintain one must eat a whole machine-made matza at the Seder, while others are more liberal and require only half of a matza or even only five percent of a matza. [Who says only 5%? If you know, post it in the comments. Thanks!] While eating a whole matza is usually not a problem for healthy people, it is for some, and especially for celiacs, whose digestive systems are highly disturbed by the gluten in wheat flour; some buy special, expensive matza made of oats, which do not contain gluten, but too much of these can cause digestive problems.
Kislev and his colleagues said Syrian olives, which each weigh 2.5-3.5 gr., and Nabali, which each weigh 4-6 gr., were common in this area during Talmudic times. About 2,000 well-preserved olive pits of these two varieties were identified in archeological digs at the Masada fortress near the Dead Sea - destroyed in 73 CE. In addition, the Bar-Ilan researcher said, there are dozens of three-millennia-old olive trees of these strains around the country that still produce fruit.
The same types of olive pits from the time of the ancient Roman Empire have been found in digs at Pompeii and Herculaneum in Italy, the researchers said. The pits were preserved for thousands of years under the lava of a volcano that erupted in 79 CE.
Thus, the researchers concluded that when Joshua led the Jewish People into the Promised Land [sic], and later at the time of the First Temple, olives were much smaller than today, and our ancestors carried out the commandment of eating matza by consuming very small pieces weighing about 5 gr., the measure of olives from that time....
Now, the exception.
A friend of mine, both a physician and a rabbi, once asked Rabbi Shlomo Zalman Auerbach what the real size of a kezyit (olive) is. This was meant as an academic exercize, not as halakha to be followed (except, perhaps, in cases of illness or emergency).
RSZA answered by tapping a fingernail.
The Rabbi-Doctor asked for clarification. Did RSZA mean the entire digit or just the nail area?
The nail area, RSZA responded. An olive the size of the fingernail (but correctly proportioned).
Unfortunately, RSZA didn't publish his opinion (as far as I know).
Too bad he didn't. If he had, haredim would now be trumpting his "uncanny insight" and "da'as Torah" as they continue to consume matzo in quntities that would have killed Moses.
As it is, we'll have to be content in knowing that our indigestion and constipation is truly a mitzva d'rabbanan, sent directly from the rabbis to you.
God isn't sadistic enough to do this to anybody.