Biblical Genetics 2 August 2013
Modern genetic science and Biblical history provide new ways of looking at old questions. Joseph Adams explores how.
Biblical history and modern genetics may not seem like obvious bedfellows; Biblical scholars tend to be found in the small corners of humanities and divinity departments at universities, surrounded by dusty books and dead languages;
geneticists can be found in the
laboratories, surrounded by the whirring and clicking of expensive machinery and supercomputers. Two separate worlds, two separate sciences and two very distinct approaches to research. Surprisingly however, the two have found themselves of use to each other.
A Human Story
Biblical history is of course epic. It tells the story of humanity, albeit with a focus on the Middle East, but that is where much of the action in the human story took place anyway. Historians and archaeologists have long asked the question as to what extent the Bible can be used as a reliable source of history. Most agree that it is indeed possible to use the Bible to shed light on history, provided you’re not too worried about the specifics. That said, genealogical history in the Bible was rarely taken seriously. After all, the Gospels list Jesus’ parentage back to Adam which is at most 76 generations – thus providing only a few dozen centuries for all of human history. The genealogical histories of the Bible are what lead young Earth creationists to argue that the earth is at most five thousand years old.
So it is perhaps surprising that modern scientists have used the Bible to explore our shared genetic history. Our DNA doesn’t just contain information about our height, physical features and skin colour. It also contains the story of our past ancestors. Through the mitochondrial DNA of a person, their maternal genetic history can be traced. This technique led to one of the most revealing discoveries in history about humanity; we all share a common mother – dubbed Mitochondrial Eve. Likewise, by tracing the Y chromosomes (only found in males), the same can be done for a person’s paternal history. This has similarly shown that every human being on earth is related via a common father. It should be clarified that our genetic ‘Adam’ and ‘Eve’ have very little bearing to the Biblical Adam and Eve, and it would be somewhat naïve to suggest so. The two were certainly not contemporaries, but rather reflections of our shared paternal and maternal ancestry.
The interesting part comes next. It is the Jews who presented the most interesting example to study. They are one of the oldest ethno-religious groups in the world – the Hebrew Bible having been preserved by Jews for millennia. Their distinct identity has been passed down through countless generations, and ultimately much of the Old Testament is a story about Jewish history.
Genesis tells the story of the first man, Adam, and a broken covenant. A covenant is established once again through the Patriarch Abraham. Abraham has two sons, Isaac and Ishmael. Isaac begets Jacob. Jacob, also known as Israel, has 12 sons. Each son is father to one of the twelve tribes of Israel. One of his sons, Judah, is the acclaimed father of all Jews. So how does this stack up against the genetic history of the Jewish people?
Geneticists from Technion (Haifa), the University College of London and the University of Arizona took on the challenge. Some academics, such as Batsheva Bonne-Tamir, have established a career researching Jewish genetic history. Batsheva is the head of the National Laboratory for Genetics of Israeli Populations in the Tel Aviv University School of Medicine which has made a number of interesting discoveries. The most significant of which is that the Jewish DNA sampled from Israel, the USA, and England all shared key markers that indicated a shared ancestry. Thus throughout the generations, through countless conversions and marriages, the Jewish people have maintained a link to one another – a huge and extended family tree.
It gets more interesting when you look at the theological teachings of Judaism. In traditional Jewish teaching, only the sons of Aaron can be high priests, responding to the responsibility given to Aaron and his sons in Exodus. The Torah reads: –
“In the tent of meeting, outside the curtain that shields the ark of the covenant law, Aaron and his sons are to keep the lamps burning before the LORD from evening till morning. This is to be a lasting ordinance among the Israelites for the generations to come.” Exodus 27:21
“Have Aaron your brother brought to you from among the Israelites, along with his sons Nadab and Abihu, Eleazar and Ithamar, so they may serve me as priests.” Exodus 28:1
Adhering to this commandment, Jewish high priests have always traced their lineage back to Aaron, and this priestly genealogy is indicated through the surname Cohen. Even in the modern day, Jewish priests are chosen from amongst the supposed descendants of Aaron. When the geneticists from Haifa, London and Arizona examined the DNA of those with the Cohen surname, they indeed found a unique genetic marker that indicated a single paternal ancestor. This marker is called the Aaron Haplotype.
Genetic history and Biblical genealogy thus stack up quite well, and the epic scale of the Bible is suited to pointing scientists toward interesting areas to look for genetic intricacies.
Old Questions, Modern Answers
But are there ways in which genetic history can help resolve Biblical disputes? Perhaps so. Following the destruction of the Jewish temple in Jerusalem in AD70 by the Roman Empire, the Middle-Eastern Jews began spreading across the world, founding new homes in Europe, North Africa and Persia. This led to two distinct Jewish groups emerging, the Ashkenazi Jews who trace their heritage through Europe, and the Sephardic Jews with Middle-Eastern and Mediterranean ancestry. Relations between these two groups are not always cordial, and a common accusation to undermine the claims of Ashkenazi Jews was to accuse them of not being ‘true’ Jews through ancestry, but rather the descendants of Turkish and Slavic converts. The theological significance being that they are not part of God’s Chosen People through blood, but rather gentiles who adopted practice of the Jewish religion. Genetic tests however found Ashkenazi Jews and Sephardic Jews as sharing many of the common Middle-Eastern Jewish markers that indicated they were indeed from the same genetic pool two thousand years ago.
The Lemba are black Africans from Southern Africa. They are distinct from nearby African tribes however in that they trace their lineage back to Jews from the Arabian peninsula. They practice a Judaic religion and adhere to dietary customs that reflect those of modern-day Orthodox Jews. They claim to be descended from Jews who, like the Ashkenazi and Sephardic communities, left Jerusalem after the Roman expulsion. Few took their claims seriously until 1997 when the DNA of the Lemba were analysed. Remarkably, they too shared the genetic markers that revealed Jewish ancestry. Even more so, the most senior Lemba clans who were responsible for overseeing religious functions had the Aaron Haplotype, hinting at the preservation of the priestly hierarchy of Judaism.
There are however limits to what DNA testing can tell us. The Pashtuns of Afghanistan and Pakistan, for example, preserve stories that indicate they are descended from Jacob and his twelve sons. Given that Jews, descended from Judah, only account for one of the twelve tribes of Israel, it is tempting to think that perhaps the Pashtuns could be descended from another. Pashtun families are organised in tribal units that reflect traditional Biblical models. Even tribal names indicate at possible roots (such as Yusufzai, or the Sons of Joseph). Genetic testing however has thrown up no definitive answer. The Pashtuns certainly share ancestry with the Jews, but so does every other human being on the planet – there were no indications that they shared a closer link to the Jewish people than anyone else. This does not mean the Pashtun folk stories are not true, but genetic testing is unable to help us resolve this mystery.
It would be wrong to give the impression that genetic tests are sure-fire ways to ascertain ancestry. They’re not. If a Jewish rabbi did not test positive for the Aaron Haplotype, then that does not mean he is not descended from Aaron. It is largely a game of probability. Human beings all share more than 99% of their DNA, we are all remarkably similar. The tests that may indicate Jewish ancestry are based on probability, tracking the percentages and probability of certain chromosomes appearing amongst particular groups in particular geographic areas at particular times.
It is worth mentioning that biology has all but abandoned the notion of human races, which are largely a social rather than physiological construct. When we speak of the differences between a pale Nordic European and swarthy Spaniard, we are essentially recognising the smallest of differences in appearance to which we attribute cultural difference. Another way of highlighting the fallacy of race is that two Africans are more likely to be more genetically distinct from each other than the west-most European and the east-most Japanese. As all non-Africans are descended from a single tribe that left Africa some tens of thousands of years ago, non-Africans are generally more closely related than two Africans.
Being overly fixated on discovering the ‘truth’ behind claims of ancestry also strikes me as somewhat missing the point. Communities acknowledge the inheritance of previous generations as a way of preserving values and meanings – whether or not you are directly related is somewhat beside the point.
Ultimately, it is worth remembering the one thing that the Abrahamic traditions and genetic science agree upon. Every human being living today is descended from one mother, making us all simply distant relatives. Some of the worst crimes in humanity are committed under the pretence of difference – something European Jews are certainly more than aware of. Religion and science here meet an important point of agreement – we are all united by our common humanity.