In the early days of the nineteenth century Lamarckism (named after the French biologist Jean-Baptiste Lamarck) was a popular way of trying to explain the evolution of animals and plants. The term, in general, is called “the inheritance of acquired characteristics”. When the Theory of Evolution was proposed this was seen as a diametrically opposite explanation of the issues, compared with Lamarckism.
For the rest of the 19th century and most of the 20th, Lamarckism was seen as a totally discredited theory. No one could postulate how a characteristic acquired during the lifetime of an organism could affect the DNA or genes so that it could be passed to subsequent generations. Throughout our lives our genes become changed by the environment – by things such as our diet, radiation, pollution and smoking. These events have consequences for our health. The view from classical genetics was that we don’t pass on any of these defects onto our children. When we reproduce, the genes in our eggs and sperm are wiped clean.
In the 1980s there was the realisation that a child’s genes are not always stripped of the experiencesof its parents. In other words, what parents do in their lives can be passed onto their offspring. Inthe last few years, there has been a massive increase in the amount of research into what’s called epigenetic inheritance.
This year scientists have announced that work in rodents has shown thatpoor diet and parental neglect can be seen in the genes of their offspring. Another piece of researchin rats, published in Nature, demonstrated that if fathers had a high fat diet, their daughters candevelop a form of diabetes, even though they themselves weren’t overweight or eating a high fatdiet. This means that the fathers’ sperm had been irrevocably altered by what they had been eating.
And there are some studies in humans that suggest that epigenetic effects are at work. These areretrospective studies, as it is impossible to control the lives of people in same way as researcherscan with laboratory rodents.
Researchers have been following the outcome of the women who were pregnant during theprolonged famine in Holland at the end of the Second World War. Girls born to these women havebeen found to have twice the usual risk of developing schizophrenia. The lack of food producedchanges in the mothers’ DNA which could have caused changes in the brain of the daughters.
Back in 2009 in the journal Nature, Princeton biologists Laura Landweber, Mariusz Nowacki and Vikram Vijayanthis reported that these ‘mechanisms could represent an “epigenetic” pathway — a route that bypasses an organism’s normal DNA genetic program — for so-called Lamarckian evolution, enabling an organism to pass on to its offspring characteristics acquired during its lifetime to improve their chances for survival. Lamarckian evolution is the notion, for example, that the giraffe’s long neck evolved by its continually stretching higher and higher in order to munch on the more plentiful top tree leaves and gain a better shot at surviving.’
The research also could have implications as a new method for controlling cellular processes, such as the splicing order of DNA segments, and increasing the understanding of natural cellular regulatory processes, such as which segments of DNA are retained versus lost during development.
Listen to BBC Radio 4 program The Switching Point