German, Norwegian, and Irish ancestors. The family name
Cramer is probably derived from the old German word “kramm” denoting a small
shop, so perhaps my Cramer ancestors were shopkeepers. Not
much is known about my great grandfather, Adolf Cramer. He
was born somewhere in
these days of extensive genealogical Internet data bases, without knowing
Adolf was born or who his parents were, we have been unable to find him in any
records before his appearance in
Envision the “family tree” diagram of your ancestors, arranged with the parent couples of each generation on a line, parents above and children below, with the male of each parental couple on the left. This family tree forms a funnel shaped distribution that doubles in size with each preceding generation. The genetic inheritance implied by the diagram is very complex, because each individual on the chart inherited some genes and chromosomes from his father and some from his mother on the line above.
However, at the right and left edges of this family tree diagram, things are much simpler because these edges represent the succession of male ancestors that led to your father and of female ancestors that led to your mother. On the left edge of the diagram, the male of each generation has inherited the y chromosome of his father. On the right edge of the diagram, the female of each generation has inherited the mitochondrial DNA of her mother. To understand this, let’s review some basic genetics.
In the nucleus of each cell, everyone has 46 chromosomes, little spools of DNA that form a genetic library encoded in “base-pairs” that constitute the 4-letter the language (A,C,G,T) of genetics. The “sentences” of this language are genes, which are step-by-step procedures for constructing the proteins than make up our bodies.
Of the 46 human chromosomes, 44 of them come in two 22-chromosome sets, one set from each parent. This deck of “alleles” is shuffled and often cross-mixed in every generation. The other two chromosomes are the sex chromosomes, called x and y. The x chromosome has about 153 million base pairs encoding about 1000 working genes. The smaller y chromosome has only about 60 million base pairs encoding about 85 working genes.
Females have two x chromosomes, one received from their father and the other from their mother. Males have an x chromosome from their mother and a y chromosome from their father. Thus, along the left edge of the family tree diagram described above, the y chromosome is passed down, relatively unchanged, from father to son in each generation in a linked patrilineal chain. Therefore, in principle, I have the same y chromosome as all of my male Cramer-surname ancestors including Adolf, extending back up the time stream for very many generations.
In a similar way, along the right edge of the family tree, mitochondrial DNA is passed down, relatively unchanged, from mother to daughter in each generation to form a linked matrilineal chain. Let me explain mitochondria a bit. Outside the nucleus of every human cell, residing in the surrounding plasma, there are a large number (100 to 10,000) of small bacteria-like organelles called mitochondria. They are associated with energy production and protein synthesis in the cell. Inside each mitochondron are several copies of their basic DNA structure, small rings of DNA with about 16,568 base pairs encoding 37 working genes.
During human reproduction a fertilized cell (whether male or female) receives a few (perhaps 2 to 10) mitochondria from the egg of its mother, but it receives no mitochondria from the sperm of its father. Thus, mitochondrial DNA is passed from mother to children in every generation, with the daughters forming in a linked matrilineal chain. Therefore, in principle I have the same mitochondrial DNA as my mother, her mother, her mother, etc., also extending back up the time stream for very many generations.
In other words, Nature has provided us with ways of tracking both of the outside edges of our family tree, along the patrilineal line of y chromosomes and along the matrilineal line of mitochondrial DNA, extending all the way back up the time stream to some y-chromosomal Adam and mitochondrial Eve that came down from the trees somewhere in Africa a couple of million years ago.
Actually, this view of an unchanging genetic structure is bit na´ve, because in each generation there is a certain probability that mutations will occur in the y and mitochondrial DNA. In fact, the mutation probability in certain DNA regions can act as a kind of “clock” that permits estimates of how many generations separate gene lines with similar but not identical genetic structures.
Now getting back to tracking Adolf, the cost of DNA analysis has been falling in recent times (but it’s still not cheap). Further, the human genome is huge, and to track a relative using DNA, it is necessary to focus on specific parts of the genome that can be compared with those of possible relatives.
Fortunately, geneticists have worked out a way of doing this. As I indicated above, the y chromosome contains 85 working genes, and any mutations in these genes might have disastrous consequences, in the form of a genetic disease. However, the y chromosome also contains fairly large regions of non-coding “junk” DNA that serve no known purpose, contain nonsense sequences that repeat many times, and show fairly high mutation rates in which the number of repeats of the sequence changes. This is perhaps because the DNA replication mechanism can become confused by repeating patterns.
in the field of population genetics have developed a set of genetic “markers”,
junk DNA regions of the y chromosome in which the
repeat count has sufficient variability to distinguish the gene lines of male
individuals with some reliability. There are now a number of
commercial firms that will, for a hundred dollars or so, analyze a sample of
your DNA taken from a cheek swab and provide a set of numbers for the y
chromosome representing the number of repeats in a set of markers.
(They will also will analyze your mitochondrial DNA, but that’s another
story.). The y-chromosome analysis
represents a genetic “fingerprint” or haplotype that you share with
your ancestors but that may be very different from one family group to another.
I have tracked six of my eight great grandparents using this technology
by arranging for the y and mitochondrial DNA analysis
of myself and several of my cousins. On the
y-chromosome side, I had 46-marker analyses done for myself and
two cousins, producing fairly specific high-resolution haplotypes for each of
us. (I’d also like to find a Gleason and
geneticists have divided the genetic landscape of y
and mitochondrial marker patterns into “haplogroups”, ensembles of related
individuals that share a similar pattern of markers. For
example, the majority of individuals of European origin are most likely to fall
into y haplogroup R, which is associated with a
mutation called M207 that occurred around 26,800 years ago, as our ancestors
were resettling Europe and
(defined by mutation M201) branched off from haplogroup F (mutation M89)
thousands of years ago. It is believed to have originated in
the Near East or Southern Asia, probably in the region that is now northern
According to an article in Wikipedia, the sub-haplogroup G2c (defined by mutation M377) presents more mysteries regarding its origin and distribution than virtually any other major y haplogroup. Haplogroups that are rare in certain regions are usually more common in another and have rather clear origins in other places where they are more commonly found. G2c does not follow this pattern. It is most common by far in a region where its carriers arrived very recently, and is exceedingly rare in other regions, including it likely area of origin. The distribution of G2c is incredibly sparse and dispersed, with almost no G2c haplotypes found in very large intervening regions. This pattern is unique among y haplogroups.
G2c is rather specific to a single ethnic group in Europe, the Ashkenazi Jews,
who settled in genealogically recent times in the German and Polish regions of
So Adolf was
probably descended from the Ashkenazi Jews of Germany or
In any case, because of the recent technological advances in DNA analysis, the field of genetic genealogy is presently growing explosively, with more and more genetic databases becoming available and expanding. My tracking of Adolf is not finished. I hope that in a few years the volume of data will grow to the point where I can find more G2c matches that fit his and my haplotype. It’s almost as good as visiting Adolf with a time machine.
“Haplogroups”, Wikipedia: http://en.wikipedia.org/wiki/Haplogroups
“Haplogroup G”, Wikipedia: http://en.wikipedia.org/wiki/Haplogroup_G_(Y-DNA)
“Haplogroup G2c”, Wikipedia: http://en.wikipedia.org/wiki/Haplogroup_G2c_(Y-DNA)
Y-DNA Testing ComparisonChart: http://www.isogg.org/ydnachart.htm
Sorenson Molecular Genealogy Foundation: http://www.smgf.org
Family Tree DNA: http://www.familytreedna.com
SF Novels by John Cramer: my two hard SF novels, Twistor and Einstein's Bridge, are newly released as eBooks by Book View Cafe and are available at : http://bookviewcafe.com/bookstore/?s=Cramer .
Columns Online: Electronic
reprints of about 177 "The Alternate View" columns by John G.
Cramer, previously published in