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Subject: DNA may tell police the surname of the criminal
Date: Wed, 22 Feb 2006 13:09:16 +0000
From: Brian Randell
From today's (UK) Guardian:
How DNA may tell police the surname of the criminal
Alok Jha Wednesday February 22, 2006 The Guardian
Police will soon be able to predict the surnames of criminals whose DNA is found at crime scenes, according to research published yesterday. The technique would only work in finding men, however, as it is based on identifying similarities in the Y chromosome, which is passed from father to son.
The technique relies on research carried out by University of Leicester scientists into how Y chromosomes have spread through the British population. They analysed these chromosomes in 150 pairs of men with the same surname and found that, in a quarter of cases, the pair had matching Y chromosomes.
When the most common names were excluded from the list - Smith, Jones, Williams and Taylor, for example - the chance that two men with the same surname shared a Y chromosome jumped to 50%. The research appears in the latest edition of Current Biology.
Mark Jobling, a geneticist at the University of Leicester who led the work, said the police would need a relatively small collection of male DNA - around 40,000 people - to allow useful matches to be made. "That sounds big but the national DNA database is nearly 100 times bigger," he said. By matching the Y chromosome details of unidentified DNA at a crime scene with the database, police would get a list of potential surname matches.
"That would allow you to prioritise suspects in your investigation," said Dr Jobling. "If you have a lot of suspects - say a whole town or something - you can say we have 50 names, are these names represented here, if so let's go and interview these people."
Y chromosomes are passed from father to son mostly unaltered. Once in a while, they will acquire random mutations as they pass through the generations. Some parts of the chromosome are known to mutate less rapidly than others and, by mapping these differences, scientists can create a tree showing the relationships between different Y chromosomes.
"If men fall in different branches of the tree, there's no way they can be related to a recent male ancestor," said Dr Jobling. "If they lie within the same branch, there is a chance they are, but it doesn't prove it.
"When we do that simple test, we find that a highly statistically significant excess of pairs share a branch of the tree, much more than we expect by chance."
It is a surprising result, since there are plenty of reasons why people might have the same surname but be unrelated: many names were founded by more than one man, for example. There is also the issue of illegitimacy. The researchers predicted that more than 1% of children were illegitimate in each generation. Over many generations, this could have built up a significant error.
"Those two elements would act as a strong force to break any links," said Dr Jobling. "It was a surprise that by choosing just pairs we got a clear signal of sharing ancestors."
http://www.guardian.co.uk/crime/article/0,,1715022,00.html -- School of Computing Science, University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK EMAIL = Brian.Randell@ncl.ac.uk PHONE = +44 191 222 7923 FAX = +44 191 222 8232 URL = http://www.cs.ncl.ac.uk/~brian.randell/ ------------------------------------- You are subscribed as eugen@leitl.org To manage your subscription, go to http://v2.listbox.com/member/?listname=ip Archives at: http://www.interesting-people.org/archives/interesting-people/ ----- End forwarded message ----- -- Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE [demime 1.01d removed an attachment of type application/pgp-signature which had a name of signature.asc]