Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Mutation
Name: Matt D Carter
Status: N/A 
Age: N/A
Location: N/A
Country: N/A
Date: N/A 

Why do organisms mutate?

Not sure if you mean "how" or "how come." If the second, then it's because this ensures a variation in the characteristics of the offspring. Each new generation of cheetahs includes a few who can run faster (but need to sleep more, say) and a few who can't run as fast (but who can go longer without food), and a lot who are pretty much the same as their parents. Then the environment does its job, and whoever isn't good enough at getting food dies and has no kids. The genes for the abilities that don't do the job get deleted from the species, and the average ability of the cheetah to get food rises. By and by they become real good at it. You still need to preserve the ability to adapt to the environment at this stage because the environment changes. Evolution is what makes species improve, and the two key parts of it are mutation and natural selection (the deletion process; it's not "natural" in the sense of "normal" but "natural" in the sense of "done by Nature.") Now if you mean "how," then the answer I think is usually assumed to be deliberate errors in duplicating DNA by the cell. The machinery for copying DNA is just set up so that every now and then it copies the recipe for a new cell as "1 egg and 1 eye of newt" instead of "1 egg and 1 teaspoon baking soda." X-rays and certain chemicals increase the rate of mutation, but I'm not sure this is significant in general.

Christopher Grayce

Click here to return to the Biology Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory