Which came first, the chicken genome or the e...( Which came first the chicken genome ...)

Which came first, the chicken genome or the egg genome?

Researchers have answered a similarly vexing (and far more relevant) genomic question: Which of the thousands of long stretches of repeated DNA in the human genome came first? And which are the duplicates?

The answers, published online by Nature Genetics on October 7, 2007, provide the first evolutionary history of the duplications in the human genome that are partly responsible for both disease and recent genetic innovations. This work marks a significant step toward a better understanding of what genomic changes paved the way for modern humans, when these duplications occurred and what the associated costs are in terms of susceptibility to disease-causing genetic mutations.

Genomes have a remarkable ability to copy a long stretch of DNA from one chromosome and insert it into another region of the genome. The resulting chunks of repeated DNA called segmental duplications hold many evolutionary secrets and uncovering them is a difficult biological and computational challenge with implications for both medicine and our understanding of evolution.

The new evolutionary history, published in Nature Genetics, is from an interdisciplinary team led by biologist Evan Eichler from the University of Washington School of Medicine and computer scientists Pavel Pevzner from University of California, San Diego.

In the past, the highly complex patterns of DNA duplication including duplications within duplications have prevented the construction of an evolutionary history of these long DNA duplications.

To crack the duplication code and determine which of the DNA segments are originals (ancestral duplications) and which are copies (derivative duplications), the researchers looked to both algorithmic biology and comparative genomics.

Identifying the original duplications is a prerequisite to understanding what makes the human genome
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