'Junk DNA' uncovers the nature of our ancient ancestors

'Junk DNA' uncovers the nature of our ancient ancestors
The sea lamprey

The key to solving one of the great puzzles in evolutionary biology, the origin of vertebrates -- animals with an internal skeleton made of bone -- has been revealed in new research from Dartmouth College and the University of Bristol.

Vertebrates are the most anatomically and genetically complex of all organisms, but explaining how they achieved this complexity has vexed scientists. The study, published today [20 October] in claims to have solved this scientific riddle by analysing the genomics of primitive living fishes such as sharks and , and their spineless relatives such as sea squirts. 

Alysha Heimberg of Dartmouth College and colleagues studied the family relationships of primitive vertebrates. The team used microRNAs, a class of tiny molecules only recently discovered residing within what has usually been considered 'junk DNA', to show that lampreys and slime eels are distant relatives of jawed vertebrates.

Alysha said: “We learn from our results that lamprey and hagfish are equally related to jawed vertebrates and that hagfish are not representative of a more primitive vertebrate, which suggests that the ancestral vertebrate was more complex than anyone had previously thought.

“Vertebrates have been evolving for hundreds of millions of years but still express the same microRNA genes in the same organs as when they both first appeared.”

The team went on to test the idea that it was these same ‘junk DNA’ genes, microRNAs, which were responsible for the evolution origin of vertebrate anatomical features. They found that the same suite of microRNAs were expressed in the same organs and tissues, in lampreys and mice.

Co-author, Professor Philip Donoghue of the University of Bristol’s School of Earth Sciences, said: “The origin of and the origin of these genes is no coincidence.”

Professor Kevin Peterson of Dartmouth College said: “This study not only points the way to understanding the evolutionary origin of our own lineage, but it also helps us to understand how our own was assembled in deep time.”

Explore further

New piece in the jigsaw puzzle of human origins

Citation: 'Junk DNA' uncovers the nature of our ancient ancestors (2010, October 20) retrieved 15 April 2021 from https://phys.org/news/2010-10-junk-dna-uncovers-nature-ancient.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments