Jared Diamond gives four possible explanations for Tay-Sachs disease:
1. New mutation of the gene could be arising at the same rate copies disappear with the death of Tay-Sachs children
2. The Tay-Sachs gene could have been acquired by other people who already had the gene at high frequency (there is some speculation that the Ashkenazim could have been descended from the Khazar, who might have carried the Tay-Sachs gene).
3. The theory which Diamond believes is that the Tay-Sachs gene may be helpful to heterozygote people, similar to the sickle-cell gene being a preventative agent to malaria in heterozygote people. In the Tay-Sachs case, the gene might be helpful against tuberculosis.
4. Genetic drift and/or the founder effect could be responsible for the high frequency in Ashkenazim.
Diamond does not believe the found effect or genetic drift could be a significant agent for Tay-Sachs disease. One reason he gives is that either of these evolutionary mechanism only occur in small populations, and there is no hard evidence that the Ashkenazim began as a small population. He also argues that Ashkenazim communities were rather widespread, so each event of drift would have had to have been independent of each other. He concludes that natural selection would have been able to restore gene frequencies to normal by now.
Glausiusz argues that genetic drift is an important agent to the high frequency of certain diseases in the Ashkenazim. First, immigrant Jew rarely ever married outside of their community and that there is some evidence that their original population was small. Both of these are excellent indicators of the presence of the founder effect.
Other bits of evidence she gives are that many older ITD carriers originated from Lithuania and Belurussia. With this occurrence, what most likely happened was that the original carrier(s) of the gene probably cam from one of the two places and their descendents spread it through the Jewish Pale of Settlement. Another indicator may be because of the different birth rates present in Ashkenazim society. What may have happened is the more desirable people of the affluent classes (business and community leaders, scholars and rabbis) may have passed the genetic disease(s) among their many children.

The Gundestrup Cauldron- Depicts a wide variety of Celtic deities

Fitting the pieces of the puzzle to Celtic history is tricky, since they wrote nothing. The only sources of information we have are second hand accounts of the Celts and archaeological evidence.
Since it is true that a “conqueror always writes the history…we have to piece together the early history of Celts from the hostile viewpoints of the Greeks and Romans (Ellis 1990). Everything recorded by the Greeks and Romans are dripping with bias. When they first encountered the Celts, their immediate impression was how barbaric they seemed to be. This was due to their lack of knowledge concerning their culture. And the fact that the Celts would run into battle stark naked wearing only sandals and jewelry probably did not help matters much, either. Because of this, all information gained from the Greeks and Romans are fogged by their immediate prejudgment of the Celtic culture.
This is not to say that everything the Romans recorded should be dismissed as being too one sided to be reliable. The recounting of their religious beliefs and myths are very helpful today in understanding the Celtic culture. Much of what we know about religion and mythology in Celtic society is in fact based on information gather by classical scholars.
Our most reliable source of information, therefore, is the archaeological record. As Frank Delaney (1986) remarks, “…without the archaeologists, the Celts might well have remained in the glowing hand of the literary and oral romantics.” That is to say, everything that we know would be embroidered to fit a good story, instead of sticking to the truth. Some of what archaeologists have found have in fact supported past observations on these people. Other finds have given even more information with which to decipher the Celtic past. Our knowledge of their style of art (the common ‘swirly’ figures) and lasting monuments have given tremendous insight on this ancient society.
And so we continue on our search for more puzzle pieces to put together our image of the Celts. Some pieces that have been acquired have fit tightly, others are skewed with the bias of the Greeks and Romans, and there are still more to be found. The mystery that surrounds the Celtic culture is slowly yet surely being exposed.

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