What is the Secret to Jewish Immortality?

In his famous essay "Concerning the Jews," published in 1898, Mark Twain presents his profound wonder about the Jewish people:

"The Jews constitute only 1% of the human race... It suggests a nebulous, dim puff of stardust lost in the blaze of the Milky Way. Properly, the Jew ought hardly to be heard of; but he is heard of, has always been heard of... His contributions to the world's list of great names are way out of proportion to the weakness of his numbers.