Ancestry Magazine

Today, a computer and Internet connection are indispensable tools for most genealogists. Three years ago, DNA testing was beyond the reach, practically and economically, of genealogists.

The jury is still out on whether genealogy is a science, in spite of Val D. Greenwood’s clear and persuasive exposition twenty years ago in the first edition of The Researcher’s Guide to American Genealogy (third edition, GPC, 2000). He notes that genealogists use the scientific method to reach conclusions by first formulating hypotheses based on existing knowledge and then designing research programs that will produce data to support or discredit a hypothesis. Some, however, still hold that genealogy is not a branch of learning but merely an intellectual pastime because it lacks academic recognition and degrees based on a formal course of study.

Nevertheless, genealogists are rushing to take advantage of new technologies based on recent scientific discoveries, and scientists in other disciplines are applying traditional genealogical research techniques to the understanding of human heredity. Twenty years ago, a few intrepid genealogists began using the new personal computers to assist their work. Today, a computer and Internet connection are indispensable tools for most genealogists. Three years ago, DNA testing was beyond the reach, practically and economically, of genealogists. In May of this year, one of the new firms offering testing services to genealogists, Family Tree DNA of Houston, passed the 10,000 mark for the number of samples tested or in process.

Meanwhile, a major scientific study, the Iceland project of deCODE Genetics, is using genealogical methods to learn more about inherited factors that contribute to fifty common diseases. Iceland’s remarkable records, stretching back over 900 years to its early inhabitants, are being used to determine the ancestry of all the island’s inhabitants. Its Book of Icelanders database, with over 680,000 entries, now includes an estimated fifty percent of the people who have lived on the island since it was first settled in the ninth century, and covers ninety-five percent of all Icel anders since the first island census was taken in 1703.

Science Serving Genealogy
When we look back at the twentieth century, one of its most striking features is how quickly new scientific discoveries were put to practical use through a series of rapid advances in technology.

It’s been just fifty years since the two biochemistry researchers James D. Watson and Francis Crick discovered the double-helix structure of the DNA molecule and outlined how it might determine heredity. Developments in technology during the intervening half-century now make it possible for family historians to verify or reject possible relationships that can’t be determined through records by using the scientific evidence of distinctive DNA patterns. We can now submit DNA samples from pairs of people thought to be related through the same all-male or all-female line, and within a month learn definitively whether they share a common male or female ancestor.

Similarly, the discovery of the transistor a few years earlier than the DNA structure has now been applied to a wide variety of practical uses through technology, making possible, among other developments, the personal computer and the Internet, two advances that have greatly expanded our options for searching out and recording genealogical evidence.

We don’t have to understand molecular biology to use DNA comparisons in our family history research, nor do we need to understand particle physics to use computers, but it’s sometimes helpful if we have a nodding acquaintance with the principles underlying the technology that’s now at our fingertips.

DNA, or deoxyribonucleic acid, consists of two long strands of small molecular building blocks labeled A, G, C, and T. The order in which thousands or millions of these units are arranged along a single DNA strand contains the genetic code that makes us human—more than 99.99 percent of the total—and then the tiny fraction—less than one part in 10,000—that identifie s each of us as individuals, and codes for the distinctive characteristics we inherit from our parents.

Two types of DNA are particularly useful in genealogical studies because they are passed on essentially unchanged from parent to child— Y-chromosome DNA (Y-DNA), from father to son in the male line, and, separate from the chromosomes, mitochondrial DNA (mtDNA), from mother to both sons and daughters, but passed on only by daughters, so that its transmission is limited to the all-female line.

The transistor, discovered in 1947, was first applied practically a few years later, providing peanut-size replacements for light-bulb-size vacuum tubes. Then, through the technology of integrated circuit boards, the components were reduced to microscopic size, making possible today’s microcomputers that can store the billions of bits needed to represent our numeric, alphabetic, and graphic data, and process them almost instantaneously into more useful forms.

Computers and the Internet both function by reducing all data to a series of bits that each contain only two items of information, such as 0/1, on/off, and yes/no. At first these elementary bits of information were recorded by the presence or absence of holes punched on a paper card or along a paper tape. More recently, they have been represented by the plus or minus magnetic polarity of a particular spot on a magnetic tape or disk, or by the off-on reflection of light from a spot on an optical compact disk. In each case they are entered or changed from one value to the other through the on-off flow of an electric current. Different zero or one values in three such bits, for example, can represent zero and the first fifteen numbers, providing the basis for the hexadecimal numbering system built into most computer systems. On or off values in seven such bits can represent each letter, numeral, and symbol in a 128-character alphabet, with both capital and lowercase letters. By using eight bits, the number of available characters can be expanded to the 256 available in most word-processing programs.

Genealogy Serving Science
The project now underway in Iceland seeks to identify the inherited factors that contribute to fifty or more common diseases. It will compare DNA samples from 80,000 volunteer participants whose ancestry is being determined from documentary records, and then evaluate their health records in light of the family relationships discovered.

The immediate genealogical objective is to link all of Iceland’s present inhabitants with their paternal and maternal ancestors from the period 1849 to 1892, and then from the period 1698 to 1742.

The ancestral determinations are based on the unique genealogical database, called the Book of Icelanders, described earlier. Its data on 680,000 past and present Icelanders was compiled from the wealth of public-domain resources available, including public registry data, church records, and pedigrees for particular families or geographic areas that go back to the original settlement and the Icelandic sagas.

The volunteers represent about one-third of the present adult population of the island, and more than ninety percent of those over sixty-five years of age. It was the comprehensiveness and accuracy of the available genealogical data that led deCODE to use Iceland for the population-wide study of inherited factors that contribute to common diseases.

In a later analysis phase of the program, sophisticated software systems will allow encrypted IDs of a list of patients with a particular disease to be run against the genealogy database encrypted with the same key, identifying extended families where a factor is particularly prevalent. Further analysis will then attempt to identify from their DNA samples those segments of the genome inherited by related patients.

A recent paper based on project data reports that the generally accepted length of time between generations—twenty years for female lines, twent y-five years for male lines—is unrealistically short. Data from the Iceland project, which is also consistent with data from contemporary hunter-gatherer cultures in other parts of the world, indicates that a more appropriate matrilineal interval is twenty-five years, with a paternal line interval between thirty-one and thirty-eight years. 1 I checked eight all-male or all-female lines from my own family, each extending from two to six generations, and similarly found intervals longer than the previously accepted ones—a twenty-nine-year average interval in the female lines, and a thirty-four-year interval in the male lines.

Bringing Science Together
The exciting potential represented by the interdisciplinary approach of the Iceland project is still not the norm in the sciences. Researchers in general tend to remain within traditional boundaries of their individual branches of expertise, and interact infrequently with researchers from other fields.

Prospects are changing, however, and nowhere is that more evident than in recent discoveries about human progress and development before the earliest written records. For the past forty years, one individual has been at the center of much of the scholarship that has crossed the traditional boundaries that separate academic branches of learning—Emeritus Professor Luigi Luca Cavalli-Sforza of Stanford University. He has engaged in dialog with researchers from disciplines ranging from his own fields of medicine and genetics to those in fields as diverse as archaeology, anthropology, geography, linguistics, and molecular biology. They have begun to address findings in other fields of research that touched on their own, particularly when the results were not consistent.

Among Cavalli-Sforza’s numerous interdisciplinary scholarly contributions over the years have been papers or books on statistical genetics, allowing comparison of varying frequencies among a number of inherited characteristics in different popula tion groups 2 , a study of cultural transmission in relation to evolution 3 , a correlation of archaeology and genetics 4 , and an interdisciplinary review of evolution 5 . Unlike many academic researchers, he has not been reluctant to incorporate genealogy into his multidisciplinary interests, and among his lesser-known papers is one in 1969 on using computer technology to compile genealogies from vital records databases. 6

He is also the author of several works aimed at the non-specialist, explaining in non-technical terms how hereditary characteristics are passed on from generation to generation. The books don’t touch in any detail on the Y-DNA and mtDNA being used for genealogical studies, but they are a fine introduction to the interdependence of the sciences generally, to genetics in particular, and to how parental characteristics are inherited.

Notes
1. A. Helgason, B. Hrafnkelsson, J.R. Gulcher, R. Ward, & K. Stefánsson, “A Populationwide Coalescent Analysis of Icelandic Matrilineal and Patrilineal Genealogies: Evidence for a Faster Evolutionary Rate of mtDNA Lineages than Y Chromosomes,” American Journal of Human Genetics 72 (June 2003): 1370—1388.
2. L.L. Cavalli-Sforza & A.W.F. Edwards, “Analysis of Human Evolution,” Proceedings of the 11th International Congress of Genetics 2 (1964): 923—033.
3. L.L. Cavalli Sforza & M. Feldman, Cultural Transmission and Evolution, a Quantitative Approach (Princeton: Princeton Univ. Press, 1981).
4. A.H. Ammerman & L. Cavalli-Sforza, The Neolithic Transition and the Genetics of Population in Europe (Princeton: Princeton Univ. Press, 1984).
5. L.L. Cavalli-Sforza, A. Iazza, P. Menozzi, & J.L. Mountain, “Reconstruction of Human Evolution: Bringing Together Genetic, Archaeological, and Linguistic Data,” Proceedings of the National Academy of Sciences 85 (1988): 6002—6008.
6. L.L. Cavalli-Sforza, I. Barrai, & A. Moroni , “Family Reconstitution by Computer,” World Conference on Records and Genealogical Seminar, Demography and Genealogy, Part I (Salt Lake City, 1969).

Donn Devine, CG, CGI, a genealogical consultant from Wilmington, Delaware, is an attorney for the city and archivist of the Catholic Dioceses of Wilmington. He is a former National Genealogical Society board member, currently chairs its Standards Committee, and is a trustee of the Board for Certification of Genealogists.