Planet of the Apes: What is that big hunk of 'junk' DNA up to ?

Last week, in response to a media blitz promoting a $288 million DNA project called ENCODE, headlines announced that most of our DNA formerly known as "junk" was actually useful.

A number of scientists both inside the study and out took issue with this claim - which centered on the 98 percent of our DNA that isn't officially part of any gene.

Sorting the workers from the freeloaders in our DNA is crucial to understanding how our genetic code works, how it drives human evolution and influences our traits and health.

Some biologists dislike the term "junk DNA" because they already knew at least part of it is doing something essential - like regulating how the instructions in the genes are carried out.

The genes hold recipes for making proteins - the working parts and scaffolding of the body. Some of the rest of the DNA tells the genes how much of a given protein to make at any given time.

The goal of the ENCODE (Encylopedia of DNA Elements) project was to figure out which parts have those important regulatory jobs.

According to some scientists involved, they succeeded in pinning down where many of those regulators lurked and identified variants in that DNA that other studies have connected to a variety of diseases. Those findings could lead to new targets for drug research and new avenues for predictive genetic testing.

But long before this project was conceived, scientists had begun to explore our jungle of mystery DNA. The question of non-gene DNA came up in 1975, when researchers discovered that humans and chimpanzees were 98 percent genetically identical. That meant we and chimps were more closely related than mice were to rats, or chimps were to gorillas.

The researchers who did the comparison pointed out that some of our differences might stem not from the genes, but from our other DNA that is regulating the genes.

That regulatory role is crucial when animals are developing in the womb. Some stretch of non-gene DNA could, for example, signal the human brain to keep growing long after chimp brain development would have shut off.

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Planet of the Apes: What is that big hunk of 'junk' DNA up to ?