‘Junk DNA’ may hold key to the evolution of complex organisms

‘Junk DNA’ could hold the key to the evolution of complex organisms . Vertebrates, animals that possess a backbone, are the most anatomically and genetically complex of all organisms, but explaining how they achieved this complexity has perplexed scientists since the conception of evolutionary theory.

A study, published in Proceedings of the National Academy of Sciences,USA, claims to have solved this scientific riddle by analysing the genomics of primitive living fishes such as sharks and lampreys and their spineless relatives, such as the sea squirts.

Alysha Heimberg of Dartmouth College, UK and her colleagues showed that microRNAs, a class of tiny molecules only recently discovered residing within what has usually been considered ‘junk DNA’, are hugely diverse in even the most lowly of vertebrates, but relatively few are found in the genomes of our invertebrate relatives.

She explained: “There was an explosive increase in the number of new microRNAs added to the genome of vertebrates and this is unparalleled in evolutionary history.”

Co-author, Dr Philip Donoghue of Bristol University’s Department of Earth Sciences continued: “Most of these new genes are required for the growth of organs that are unique to vertebrates, such as the liver, pancreas and brain. Therefore, the origin of vertebrates and the origin of these genes is no coincidence.”

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Elaine Warburton  www.geneticsandhealth.com