Discrepancy between haplogroups and language families

All of Africa was once populated by the people we now call "sub-Saharan" Africans. This is why the San (or "Bushmen") lived near Suez 50,000 years ago when the more adventurous members of the tribe decided to walk over to Asia and become the ancestors of all non-African people. But a warming climate turned North Africa into a desert, where Paleolithic people (nomadic hunter-gatherers) couldn't get enough food to survive. So everyone migrated south. The San now live at the southern end of the continent.

Around 12,000 years ago, the Agricultural Revolution ushered in the Neolithic Era. Farming (the cultivation of plants using irrigation) and animal husbandry (the domestication of animals) caused an explosion in the quantity of food available, both permitting and requiring people to settle down in permanent villages and learn to live together in larger groups. The technology of agriculture was first invented in Mesopotamia. Figs were the first cultivated crop and sheep or goats were the first animals domesticated for meat and milk.

At some point, explorers from southwestern Asia traveled back to humanity's ancestral homeland: Africa. With the new technology of agriculture, they were able to raise enough food to survive in the desert. There are three possible versions of what happened next, and we may never know which is the correct one:

• 1. The Asian population grew until they had spread over much of the region. Eventually their explorers and the explorers from sub-Saharan Africa discovered each other. Africans moved north, learned to farm and raise animals, and lived among the Asians. Intermarriage inevitably occurred. The huge African population kept migrating north, so today their DNA dominates the gene pool. But since the Asians were the leaders of the communities, the Africans adopted their languages.
• 2. The Asian population grew slowly. Even with the bounty of food produced by agriculture, disease took its toll. When the sub-Saharan explorers discovered them, they had established a viable beachhead on the continent, but they were soon overwhelmed by African immigrants. As the leaders with the superior technology, their language dominated. Again, intermarriage occurred and the larger African population dominated the gene pool.
• 3. The sub-Saharan Africans invented the technology of agriculture on their own and managed to repopulate the Sahara. When the Asians arrived with their more well-developed agriculture, they showed them how to do it better. Intermarriage occurred. As leaders, their language dominated, but the larger African population dominated the gene pool.

So no matter how it went down, we ended up with a huge population speaking languages from all six branches of the Afro-Asiatic family (Semitic, Egyptian, Chadic, Omotic, Cushitic and Berber), yet with DNA distinctly different from the Semitic speakers in Asia.

It's not always easy to separate linguistics from anthropology. There are many places where DNA does not match up with language.

• The Bulgars were not a Slavic people. Best guess is that they were either Finno-Ugric or Mongolic, and some scholars say those two ethnic groups and language families are related anyway. But when they settled down smack-dab in the middle of the Slavic region of Europe, they adopted the Old Slavonic language, and today their descendants speak Bulgarian, a Slavic language.
• The Jews are a Semitic people, but they long ago gave up Hebrew as a vernacular language and made a habit of adopting the languages of their host peoples. The largest Jewish population ended up in Europe, and they spoke Yiddish, an Indo-European language descended from medieval German. Today the largest Jewish population is in the United States, and they speak another Indo-European language closely related to German: English.
• Most of the people in Central and South America speak either Spanish or Portuguese, Indo-European languages. Yet the DNA of many (or perhaps most) of them is predominantly Native American.
• The Aramaeans were a number of separate tribes living under the rule of the Assyrian Empire. Yet their Semitic language, Aramaic, was adopted by their conquerors. (An interesting exception to the usual scenario of people adopting the language of their rulers.) Even after the demise of the Assyrian Empire and the virtually complete disappearance of the Aramaeans, Aramaic remained the vernacular language of the entire Middle East right up into the 20th century, spoken by a huge population of Jewish, Arabic, Palestinian, Lebanese, Persian, Turkic and other peoples.

You just can't expect language and DNA to correlate perfectly.