Epigenetics Comes of Age

Ask a biology student on what determined evolutionary transitions from a body plan to another or even from a species to a closely related species and he unhesitantly will tell you that it is a natural result of changes in existing genes and the evolution of new genes under the action of natural selection. A more advanced student, from a neo-genetic standpoint, will tell you that changes in regulatory sequences of genes may be all that is needed for the evolution of living forms.

Most biologists still believe in one of the above explanations as the cause of evolution, despite the lack of pertinent evidence.

However, butterflies, frogs and even humans, defy - if not mock - these explanations: with the same genes and the same regulatory sequences a butterfly, within its life time, builds two very distinct body plans of two different  phyla, of a worm and of an insect; a frog builds first the Bauplan of a fish then that of an amphibian. We have more than 98% of our genes in common with a chimp, but look at the huge differences in physiology, morphometry, morphology, behavior and cognitive capabilities.

If extant organisms, with the same genetic toolkit can produce such different Bauplane, why could worms not evolve into insects and fishes into amphibians with the same genes and regulatory sequences, without changes in  their DNA?

I don’t believe any biologist would seriously claim he could produce a human being by replacing 2% of the genes in chimp gametes with human genes (the whole early embryonic development is determined by epigenetic information, by parental (maternal and paternal) cytoplasmic factors arranged in strictly determined spatial patterns in gametes of each species).

This entry was posted on Thursday, June 17th, 2010 at 5:20 pm and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.