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Name: Brittany
Status: Student
Grade:  12+
Location: CO
Country: United States
Date: October 2008

Why do humans have extra DNA?

One explanation is that we simply don't know its function yet (but that doesn't mean it doesn't have a function). Another is that a mutation or other change has rendered a sequence non-functional, but the remaining sequence remains in our genome.

Hope this helps,

All eukaryotes have extra DNA. One theory is that it provides for the evolution of new genes which, of course, is the raw material for future evolution.

Ron Baker, Ph.D.

I'm not sure I fully understand what you are asking. However, here are to items that may address your inquiry. First, some DNA (and other substances, cells, and even organs) contain redundant, i.e. backups in case something fails. Two examples and the kidney and liver. If those organs, and hence their cells right down to their DNA, stop functioning they can continue to function. Second, only a fraction of the functions and use of DNA is known. The use of major amounts of the DNA remains unknown. This has been called "junk" DNA. But that is not a good name. It's not "junk" we just don't yet know what its function is.

Vince Calder

There is one idea about this topic that suggests that this DNA may be left over as a result of evolutionary processes. Advanced organisms may have left over DNA from their ancestry prior to being our current stage of "Homo sapiens", for example. Humans have a great deal of identical or similar genes to fish, reptiles, etc., but, of course, we have evoled to a different stage of development. We just have previously used.but now junk DNA in our genome, much like left over crumbs.

Steve Sample

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