Autism Vox

Changing Environment, Changes in Genetic Structure

by Kristina Chew, PhD on November 14th, 2007

Many say that a child may have a genetic “predisposition” to autism, or a weak immune system, etc., but that some “environmental factor” is “triggering” autism: How do genes and the environment interact? Rice University physicist and bioengineer Michael Deem has a new theory about how the changing environment may influence genetic structure. As noted in the November 14th Science Daily:

The study by Deem and postdoctoral fellow Jun Sun found the structure of genetic information becomes increasingly modular when two conditions are taken as givens: horizontal gene transfer (HGT) and a changing environment. Like modular furniture that can be rearranged in different functional patterns, modular genes are standardized components that lend themselves to flexible rearrangement, and this genetic modularity arises spontaneously because of the selective pressure of a changing environment and the existence of horizontal gene transfer.

Genes are typically transferred vertically. People, plants and animals pass genes vertically, from generation to generation, through sexual reproduction. Bacteria transfer genes vertically via conjugation. HGT allows genes, pieces of genes and collections of genes to move between species, even in cases where vertical transfer is physically impossible.

Though scientists have known about HGT for years, it was thought to be rare and infrequent until sophisticated tools opened the genetic history of many species in the 1990s. Today, HGT is widely accepted as the primary reason for antibiotic drug resistance, and Deem said HGT played a significant role in human development as well. “Our acquired immune system is a product of horizontal gene transfer and is organized in a modular fashion,” he said.

The fitness of an organism—-its likelihood to succeed—increases as the modularity of its genetic code does, Deem finds. And, as the genetic code’s modularity increases, so does the “web of life” become more complex and varied and “intricate.” Says Deem:

“‘Our results suggest that the beautiful, intricate and interrelated structures observed in nature may be the generic result of evolution in a changing environment……….The existence of such structure need not necessarily rest on intelligent design or the anthropic principle.’”

There is evolution of gene structures “in a changing environment”: Perhaps it is not only the environment that changes but the something about genes themselves.

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POSTED IN: Environment, Genetics