An ambitious hunt by Johns Hopkins scientists for actively "jumping genes" in humans has yielded compelling new evidence that the genome, anything but static, contains numerous pesky mobile elements that may help to explain why people have such a variety of physical traits and disease risks.As a species, we mutate at the drop of the proverbial hat.
Using bioinformatics to compare the standard assembly of genetic elements as outlined in the reference human genome to raw whole-genome data from 310 individuals recently made available by the 1000 Genomes Project, the team revealed 1,016 new insertions of RIPs, or retrotransposon insertion polymorphisms, thereby expanding the catalog of insertions that are present in some individuals and absent in others. Their results appeared online October 27 in Genome Research.
Retrotransposons are travelling bits of DNA that replicate by copying and pasting themselves at new locations in the genome. Having duplicated themselves and accumulated over evolutionary history, transposable elements now make up about half of the human genome.
"In any individual, only between 80 to 100 retrotransposons are actively copying and inserting into new sites," says Haig Kazazian, M.D., professor of human genetics, McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine. "We're not only discovering where they are and who has which ones, but also finding out that they insert with a remarkable frequency: On the order of one in every 50 individuals has a brand-new insertion that wasn't in their parents."
From Science Daily again, in 2009: 'Jumping Genes' Create Diversity In Human Brain Cells, Offering Clues To Evolutionary And Neurological Disease :
Rather than sticking to a single DNA script, human brain cells harbor astonishing genomic variability, according to scientists at the Salk Institute for Biological Studies. The findings, to be published in the Aug. 5, 2009, advance online edition of Nature, could help explain brain development and individuality, as well as lead to a better understanding of neurological disease.So not only are we remarkably diverse in terms of genetics from our parental genetic line... our bodies are genetically diverse at the cellular level, especially within the brain. Not nearly as genetically promiscuous as bacteria in a bucket of seawater, which swap gene sequences between species with gay abandon, but it looks like we might be unusual here compared with other mammals. What makes us the kind of people that dominate the planet is due to our brains; but that cranial capacity might be an effect of being unusually flexible in our internal genetic diversity.
The team, led by Fred Gage, Ph.D., a professor in the Salk's Laboratory of Genetics and holder of the Vi and John Adler Chair for Research on Age-Related Neurodegenerative Diseases, found that human brain cells contain an unexpected number of so-called mobile elements—extraordinary pieces of DNA that insert extra copies of themselves throughout the genome using a "copy and paste" mechanism.
"This is a potential mechanism to create the neural diversity that makes each person unique," says Gage. "The brain has 100 billion neurons with 100 trillion connections, but mobile pieces of DNA could give individual neurons a slightly different capacity from each other."
Having such flexibility might make our species short-lived, as a species. But it could lead to a family of Mankinds, just as it may have done in the past. It also has some advantages, in that it lessens the likelihood of some Killer Bug getting all of us. Some of us will inevitably succumb to even minor illnesses, genetically vulnerable. But some of us will be sufficiently different so that 100% wipeout is impossible. We may be as difficult to eradicate as cockroaches - though those of our descendents that survive might be as different from us as H Neanderthalis is from H Sapiens.
Diversity - not just a good idea, it's what makes us Human. E Pluribus Unum.