...Since all human beings have virtually identical DNA, geneticists have to look for slight chemical variations that distinguish one population from another. One technique involves the use of "microsatellites" - short repetitive fragments of DNA whose patterns of variation differ among populations. Because microsatellites are passed from generation to generation and have a high mutation rate, they are a useful tool for estimating when two populations diverged.

In their study, the research team compared 377 microsatellite markers in DNA collected from 1,056 individuals representing 52 geographic sites in Africa, Eurasia (the Middle East, Europe, Central and South Asia), East Asia, Oceania and the Americas.

Statistical analysis of the microsatellite data revealed a close genetic relationship between two hunter-gatherer populations in sub-Saharan Africa - the Mbuti pygmies of the Congo Basin and the Khoisan (or "bushmen") of Botswana and Namibia. These two populations "may represent the oldest branch of modern humans studied here," the authors concluded.

The data revealed a genetic split between the ancestors of these hunter-gatherer populations and the ancestors of contemporary African farming people - Bantu speakers who inhabit many countries in southern Africa. "This division occurred between 70,000 and 140,000 years ago and was followed by the expansion out of Africa into Eurasia, Oceania, East Asia and the Americas - in that order," Feldman said.

This result is consistent with an earlier study in which Feldman and others analyzed the Y chromosomes of more than 1,000 men from 21 different populations. In that study, the researchers concluded that the first human migration from Africa may have occurred roughly 66,000 years ago.

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Most people know little about today's Samaritans. Many believe that the name refers to an ancient Biblical race of which no vestige survives. They are often surprised to learn that the Samaritans, who accept only the Pentateuch as Holy Writ, are a vital, intelligent group with a rich history and a distinctive language and literature, practicing their own form of worship and following age-old traditions and customs.

They claim direct descent from Ephraim and Manasseh, sons of Joseph, who entered the Promised Land with Joshua and settled in the Samaria region; while their priests stem from the tribe of Levi. The Samaritans rather resent the name by which they are known; preferring to call themselves "Shamerim" --in Hebrew, guardians-- for they contend that they have guarded the original Law of Moses, keeping it pure and unadulterated down the centuries.

Their numbers are not large, and today less than five hundred are left of a great nation that is said to have been counted in hundreds of thousands --there were estimated to be over three-quarters of a million in the early part of the Christian era. About half of the remnant live on their ancestral site, close to Mount Gerizim (1), and the other half in Holon, near Tel Aviv.

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This is snipped from Steven Morgan Friedman's semi-regular random thoughts newsletter.

I was recently talking to a friend's wife, who teaches at Yeshiva University--the leading Orthodox Jewish university in New York--and she pointed out to me that the colors and patterns of the kippot (the little hats that Jews are required to wear at almost all times, also known as a "yarmulkes" or even "skull-caps") that students wear reveal their attitudes towards everything from Judaism and Israel, to life and pot-smoking. I pressed her for examples, and to my great interest and surprise, she recited for me the unofficial list of associated affiliations. Later, I e-mailed her and asked her for this list, which I would like to share with you now, with, of course, the caveat that these are just one keep observer's insights from one social context:

- Black velvet is worn by the most frum [very observant] men: Lubavitchers, Chabadniks, and others in the more modern orthodox realm who are very observant

- Black leather indicates less religious but still very observant and traditional people

- Knitted yarmulkes with a white center demonstrate strong Zionism

- Knitted yarmulkes with other colors in the center don't make a specific political statement but show more openness to modernism than the black of any material; they're often made for guys by their girlfriends (especially the ones with names knitted into them) but not always

- Knitted yarmulkes worn on the very front of the head show that the wearer went to an orthodox Jewish day school

- Full-head yarmulkes (like the Sephardic-styled, embroidered ones or the knitted ones of thicker yarn than cover the head nearly to the ears) show much more openness to liberalism and modern ideologies. At YU, guys with these kippot tend to be rebels or pot-smokers or guitar players. This statement is, of course, a terrible generalization but has some kernel of truth.

- The very little yarmulkes show some kind of coolness, but I don't know what the exact statement is. Same goes for yarmulkes with smiley-faces, watermelons, Nike swooshes, names of sports teams, etc. I think those say, sure, I'm religious, but I can be cool and "with-it" too

- Guys with velvet yarmulkes under their big black hats are hard core. At YU, they are almost always Ba'al T'shuvah, but in the rest of the world they're just really really religious and tend to eschew the trappings of American capitalism.

A new computer program can determine the sex of an author by detecting subtle differences in the words men and women prefer to use.

For instance, female writers tend to choose grammatical terms that apply to personal relationships, such as "for" and "with," more frequently than men do.

"Women have a more interactive style," said Shlomo Argamon, a computer scientist at the Illinois Institute of Technology in Chicago who developed the program. "They want to create a relationship between the writer and the reader."

Men, on the other hand, use more numbers, adjectives and determiners - words such as "the," "this" and "that" - because they apparently care more than women do about conveying specific information.

Argamon said the intent of male writers often was to say: "Here's something I want to tell you about, and here are some things about it."

Women, he found, write the pronoun "she" more often than men do, although both sexes use "he" about equally.

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While we speak of matters dark:

Researchers shine their lights on noncoding sequence

The dark side of the moon is a misnomer. Light reaches la luna's entire surface, but one half is unviewable from Earth. The human genome, the now essentially decoded map of life, likewise has a light side--the genes encoding mRNA and protein--and a dark side, which is coming into view for the first time. The dark side encompasses more than its opposite: The majority of the genome comprises intronic regions, stretches of repeat sequence, and other assorted gibberish that has attained the ignoble dubbing, "junk."

The first exploratory missions to the human genome's faceted surface are turning up traces regarding the extent of the junk. At a recent National Human Genome Research Institute (NHGRI) conference, numerous presenters invoked Sydney Brenner's classic distinction: "Garbage you throw away and junk you keep, because you think you might want to do something useful with it, and of course you never do."

Comparative, computational, and experimental studies can shine light on these unexplored DNA elements. Some are known regulatory stretches; others encode RNAs but offer scarce hints at their function. Eric Green, chief of NHGRI's genome sequencing branch, says, "I think the challenge is going to be in the nongenic, functional portion of the genome."

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