DNA testing allows us to trace our paternal (fathers of fathers) and maternal (mothers of mothers) lines, but not the ones in between (e.g. mothers of fathers). Although this technique has been very useful in many different fields, it can easily be misu
A 2,100-year-old Iron Age skeleton from Bleadon, Somerset, can be linked to at least four relatives in present-day Bleadon. This is a facial reconstruction of how the Bleadon Man might have looked. Credit: Science & Society Picture Library/B.B.C.
nderstood. It can reveal only two ancestors in any given generation. This weakness is magnified by the long time-spans invo
This success implies a high degree of faithfulness
lved. Going back a few centuries, we have a million of potential ancestors, but genetics can only identify two of them directly.
By examining Y chromosomes, it has been possible to show that some surnames do share a common ancestor. This success implies a high degree of faithfulness between husbands and wives. The divergence between biological and legal parentage is called the non-paternity rate. Non-paternity can arise from sex outside marriage, adoption or simply by taking a different surname from the father (to obtain an inheritance, for instance). The observed non-paternity rate for the Sykes family, for example, was 1.3 per cent, and while this is low, it is sufficient for only half the Sykes to be genetically linked. DNA testing can also be used to discover the father of a child whose parentage is disputed, as several famous fathers have discovered to their cost.
Similar DNA tests, using samples from close relatives, can be used to identity victims of disasters such as the collapse of the Twin Towers in New York in September 2001, or the remains of the Russian royal family who were executed in 1918 and buried an
Doris Gould, DNA testing revealed that she is related to the Bleadon man. Credit: Science Museum/Science & Society Picture Library
onymously. Genetics can help us improve on conventional genealogical techniques. Most people have trouble finding ancestors born before 1800. DNA testing can reveal more distant ancestors though it cannot give us their names. In the 1970s, the Guinness Book of Records stated that the O’Neills of Tyrone had the longest family tree as they could trace their ancestry back to Niall of the Nine Hostages, who lived around AD400. The current edition of the Guinness Book of Records credits Adrian Targett of Cheddar, Somerset, as the person with the longest family tree because DNA testing by Bryan Sykes of Oxford University has reputedly linked him with the 9,000-year-old skeleton of ‘Cheddar man’ found in the Cheddar Gorge in 1903. Similarly, recent tests revealed that a 2,100-year-old Iron Age skeleton from Bleadon, Somerset, can be linked to five relatives in present-day Bleadon. The mother of ‘Oetzi’, the 5,000-year-old body found in the the Italian Alps in 1991, has a direct descendant living in Bournemouth.
Some medical conditions are caused by changes in our genetic material. They can be passed from one generation to the next. Genealogy allows researchers to trace back some of these conditions to their human origins. > more
Scientists have attempted to reconstruct the movement of different groups and the development of modern cultures. It appears we are all descended from a small group of early people, the mothers and fathers of all living human beings. > more