Posts Tagged ‘John Maynard Smith’

Scientists Mutate Flatworms without Altering Genes

November 28, 2015

This is another very interesting piece I found on Tumblr. Biologists at Tufts University have managed to make one species of flatworm grow the brains and heads of other species without altering its genetic makeup. This suggests that the body plan of living creatures may be partly determined by the bioelectric fields and synapses, and develop according to epigenetic processes. These are the biological processes that affect the shape of living being which aren’t caused by that creature’s genes.

Flatworm EvolutionPic

It’s a fascinating addition to modern evolutionary theory, which takes it beyond the simple Neo-Darwinian synthesis formulated at the beginning of the 20th century by Theodososius Dobzhansky and Fisher, amongst others. This stated that evolution worked through the appearance of mutations in living creatures’ genetic codes, which provided the raw material for the operation of Darwin’s natural selection. If the mutations proved beneficial, then the creature thrived and had more offspring, and the genes spread through the rest of that creature’s population. If the mutations were harmful, then the creature died, taking with it the faulty genes. Gradually these mutations, selected by the environment, mounted up until a new species emerged, descended from its predecessor.

This complicates the situation. There’s a theory that Lamarck based his theory that evolution was driven through inherited characteristics partly on misunderstood observations of epigenetic alterations in the animals he studied. Some of the changes can be quite dramatic. For example, some species of animal have been known to develop additions to the digestive system according to changes in diet. John Maynard Smith, one of the leaders and founders of modern Neo-Darwinian biology, also speculated in a small book published on evolution in the 1990s that the forms of living creatures may also be partly determined by the changes in the developing embryo in the very first stages of life. I’ve been told that there’s a heretical view of the development of living organisms held by a few university biologists, which states that these changes are largely responsible for the shape of the organism, with the creature’s genes determining only minor differences.

This experiment adds more information to the debate, and seems to support the indications that epigenetics – non-genetic processes – could play a stronger role in shaping living things than previously considered.