Specific DNA mutations that arise rarely in sperm and egg may sometimes over time spread among populations to become the fixed norm within a species. To measure advances in the ticking clock of evolutionary time, biological scientists like to count the accumulation of DNA changes. She also still collaborates closely with UCSC researchers, but now the banks of computers she relies on for analyzing massive amounts of data are housed at the UCSF Mission Bay site of the California Institute for Quantitative Biosciences (QB3).ĭNA Changes Are the Ticking Clock of Evolution Pollard, whose lab is all about computational ideas and experiments, collaborates with UCSF scientists who study diseases and work with biological materials. Today scientists can compare genomic data from 50 different vertebrate species, Pollard says. At that time only a handful of vertebrate genomes had been mapped out. Pollard was among the first scientists to begin comparing human and chimp DNA side by side. The consortium of dozens of researchers from universities around the world completed the map in 2005. When Pollard was a postdoctoral fellow at UC Santa Cruz (UCSC) she joined the Chimpanzee Genome Project. Other DNA differences affect the digestion of foods – not surprising when you consider how much our diets have diverged from chimp diets. She’s looking for hot spots along the genome where DNA has been evolving rapidly in humans.Īlready the top-scoring DNA hot spots to emerge from her number crunching have been shown by Pollard’s research team and other scientists to be important in brain development and limb formation. She’s analyzing not only the genomes of chimps and humans, but also the genomes of other vertebrates. To do a better job of finding out which of these spelling differences in DNA sequences are most important, Pollard has developed powerful computer software for comparing the complete genetic codes – or genomes. That’s more than anybody can look through manually.” “But when you consider that the genome is 3 billion base pairs long, that means there are 15 million human-specific letters of code that are not shared by the chimp. “Only one in 100 base pairs is different, which doesn’t sound like much,” says Pollard. No stretch of DNA escapes scrutiny – she’s looking at the entire genome. Thus equipped, Pollard is probing the places in the genetic code where base pairs – the coupled DNA alphabet building blocks that form the famous double-helix - differ between the two species. Pollard, an associate professor with the UCSF Department of Epidemiology and Biostatistics and the UCSF Institute for Human Genetics, as well as an associate investigator with the Gladstone Institute of Cardiovascular Disease, has created software programs – mathematical algorithms – to tease out vital information from DNA. In her own search for answers, Katie Pollard, PhD, has been buoyed by a decade’s worth of advances in computer power and in the tools used to map DNA at an ever faster clip. What is it about our genes that enables us to develop uniquely human capabilities? And what can we learn about familiar human vulnerabilities that we do not share with our primate cousins? The secrets are in the DNA, scientists believe. The goal is to find out more about ourselves.
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