Sunday, 8 August 2010
Why humans are different from rats?
Humans have a genome very similar to many other species. For example, more than 90% of our DNA is shared with mice and more than 95% with chimps. Why we are so different from these animals? The evolutionary developmental biology, whose nickname is Evo-Devo, proposes that morphological diversity among species is, for the most part, not due to differences in genes but in genetic switches that are used to turn genes on and off. These switches are the non-coding DNA, or the so-called "junk DNA", which are now known to be used in gene regulation. These genetic networks allow a huge number of possibilities for gene expression patterns, since there are so many possible ways in which proteins can be attached to the switches. The reason the humans share so many genes with quite different species is because, although the genes might be the same, the sequences making up switches have often evolved to be different. Small changes in switches can produce very different patterns of genes turning on and off during the development.