Which genes make us human? + What is Uniquely Human?

By | September 4, 2009

… The best guess is that the human genetic code takes in somewhere around 24,000 genes – bits of chemical code that provide the instructions for building the proteins used in our bodies. Many of these genes are shared with other species. In fact, geneticists have found that humans and their closest living relatives in the animal kingdom, chimpanzees, hold about 96 percent of their DNA in common.

Most of the differences arise from old genes that have been copied and tweaked over time to create a larger store of genes – feeding a merry-go-round of mutations that keep the evolutionary process spinning. Biologists have long surmised that such mutations add up over time to produce different species.

In addition to our genes, there are other long stretches of DNA in the genome that don’t figure in the production of proteins. Those stretches are known as “non-coding DNA” or “junk DNA,” and every species has some. It’s only been in the last few years that scientists realized that junk DNA may not be junk at all but instead can play an essential role in our genetic workings.

Three years ago, scientists discovered that bits of non-coding DNA in fruit flies actually turned into protein-coding genes. In this week’s issue of the journal Genome Research, David Knowles and Aoife McLysaght of Trinity College Dublin say they found at least three human genes that appear to have gone through a similar conversion process.

Knowles and McLysaght found the genes by running a computerized comparison of the human and chimp genomes and checking the sections that didn’t have anywhere near a close match. They identified 644 protein-producing genes in humans that didn’t produce a corresponding hit in the chimp genome. Then they took a closer look at those sections.

In 425 cases, there were gaps in the chimp genome sequence big enough to account for the missing human gene. In 150 other cases, the researchers found a match that was missed the first time around. They looked at other species as well – eventually winnowing down their list of “uniquely human” genes to just three, known as CLLU1, C22orf45 and DNAH10OS.

That wasn’t the end of the exercise. “We needed to demonstrate that the DNA in human is really active in the gene,” McLysaght said in a news release. She and Knowles verified that the genes really did play a role in producing proteins for humans, and that the protein-producing capacity was disabled for other primates. …

via Which genes make us human? – Cosmic Log – msnbc.com.

What do you suppose genes found only in humans would be responsible for?

Music as we know it? Language complexity? The physical and psychological features that enable us to speak? Extreme creativity and innovation (intelligence)? Extreme tool making, structure building and clothes creation?  A thirst for knowledge and self improvement? The ability to destroy the planet? The ability to care about saving the planet?

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