Gene Expression and Differences Between Chimp and Human


click for full-zise image
It has been proposed that minor changes in control of gene expression could result in the evolutionarily rapid and drastic differences between humans and chimpanzees. This idea is based on observations from the field of evolutionary development (EvoDevo). EvoDevo studies have demonstrated the effects of tinkering with the expression patterns (including location and timing) of master genes involved in controlling expression of other genes. The homeobox genes are a good example of this phenomenon. However, there are many ways to control gene expression ranging from more obvious regulatory regions surrounding the gene to regulation of the expressed RNA, which is not as easy to predict.

In this recent paper, the authors describe how they identified 202 regions that showed significant differences between chimps and humans, but were highly conserved between chimps and other mammals. These regions were studied extensively and compared with various other regions of the genome to determine what forces might have caused the differences between humans and other mammals, specifically chimps. They concluded that a number of evolutionary forces could be responsible for the changes, but found that most of the changes were in non-coding regions of the genome. Non-coding regions don't contain a gene, but they are responsible for regulation of genes and are where regulatory RNAs are located. In addition, these regions were often located near control genes, such as transcription regulators.

Additional studies of the HAR1 region, show that an RNA from this area is produced during human embryonic development and is found in the brain. No one is sure what it does yet, and there are at least 48 other areas of interest waiting for study as well, however these initial studies certainly support the theory that small changes in regulation of expression may be responsible for the differences between us and our nearest living relatives in the tree of life.

An overview article

The article, “Forces Shaping the Fastest Evolving Regions in the Human Genome"

Click here for more on a specific region, HAR1.

For more on these areas, click here.