There's one tiny fragment of DNA that pretty much all vertebrates and invertebrates share. It's the only piece of DNA known to be a billion years old — and it still has a role to play in shaping our genes.
Researchers at the University of Barcelona discovered the fragment, which is a noncoding sequence of DNA involved in gene regulation. While this particular fragment doesn't directly determine our physical and mental characteristics, it's one of many noncoding regions that plays a crucial role in determine how the rest of our genes are expressed, and which sets of genes are activated. It's a job this particular fragment has had for the last billion years.
The region was discovered through analysis of both vertebrate and invertebrate genomes. Researcher Jordi Garcia-Fernández explains what this all means:
"The study reveals the first evidence of a noncoding sequence region deeply evolutionarily conserved for more than 1,000 million years, which has maintained its activity in the control of neurogenesis throughout the evolution of metazoans.
"A surprising outcome of the study was the identification of a genetic sequence highly conserved over thousands of years in such different organisms, with an equally highly conserved pattern of biological functions. The results from the Drosophila melanogaster [fruit fly] model are also particularly impressive. Although until now this noncoding region had not been identified in the genome, we have found that once it is inserted it can direct gene regulatory machinery in the development of the brain and occipital lobe.
"The complexity of living beings was not produced simply by the appearance of new genes. A gene can be co-opted; that is, it can be used for a new function, and in many cases this phenomenon has paved the way for evolutionary innovation. Before it was thought that the most complex organisms derived their complexity from the possession of a larger number of genes, but this is not the case. They are complex because the same genes have been co-opted to acquire new functions."