Understanding these and other differences may help us learn what it means to be human. But it took the recent advent of whole-genome sequencing of several species and an open-minded, combined computational and experimental approach to reveal the particular two-steps-forward, one-step-back evolutionary dance that set us apart from other primates millions of years ago.
"Rather than looking for species-specific differences in specific genes or genomic regions that exist in humans, we asked, 'Are there functional, highly conserved genetic elements in the chimpanzee genome that are completely missing in humans?'" said Gill Bejerano, PhD, assistant professor of developmental biology and of computer science. "We found several hundred locations that, as far as we could see, are absent in our species alone." Until now, many evolutionary geneticists focused on differences among genes, rather than the regulatory regions outside the genes.
Losing small pieces of regulatory DNA, rather than the genes they control, means that the related changes are likely to be subtle: Although the location or the timing of the expression of the gene within the body may change, the gene product itself remains functional. The distinction leads to viable differences among individuals that can eventually lead to the development of new traits and species.
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