After publication of Charles Darwin‘s theory of natural selection, the importance of individual efforts in the generation of adaptation was considerably diminished. Later, Mendelian genetics supplanted the notion of inheritance of acquired traits, eventually leading to the development of the modern evolutionary synthesis, and the general abandonment of the Lamarckian theory of evolution in biology. In a wider context, soft inheritance is of use when examining the evolution of cultures and ideas, and is related to the theory of Memetics.
The “Vestiges of the Natural History of Creation”, authored by Robert Chambers and published anonymously in England in 1844, proposed a theory modelled after Lamarckism, causing political controversy for its radicalism and unorthodoxy, but exciting popular interest and paving the way for Darwin.
Darwin accepted pangenesis as a hypothesis based on the idea that somatic cells would, in response to environmental stimulation (use and disuse), throw off ‘gemmules‘ which travelled around the body. These pangenes were microscopic particles that supposedly contained information about the characteristics of their parent cell, and Darwin believed that they eventually accumulated in the germ cells where they could pass on to the next generation the newly acquired characteristics of the parents.
Since 1988 certain scientists have produced work proposing that Lamarckism could apply to single celled organisms. A version of Lamarckian acquisition in higher order animals is still posited in certain branches of psychology.
10.5.2 Soma to Germ-Line Feedback
In the 1970s the immunologist Ted Steele and colleagues proposed a neo-Lamarckian mechanism to try and explain why homologous DNA sequences from the VDJ gene regions of parent mice were found in their germ cells and seemed to persist in the offspring for a few generations. Little more than indirect evidence was ever acquired to support it.
10.5.3 Epigenetic Inheritance
Forms of ‘soft’ or epigenetic inheritance within organisms have been suggested as neo-Lamarckian in nature. In addition to ‘hard’ or genetic inheritance, involving the duplication of genetic material and its segregation during meiosis, there are other hereditary elements that pass into the germ cells also. Although the reality of epigenetic inheritance is not doubted, its significance to the evolutionary process is uncertain.
10.5.4 Lamarckism and Single-Celled Organisms
While Lamarckism has been discredited as an evolutionary influence for larger life forms, some scientists controversially argue that it can be observed among microorganisms.
In 1988, John Cairns at the Radcliffe Infirmary in Oxford, England, and a group of other scientists renewed the Lamarckian controversy which by then had been dead for many years. The group took a mutated strain of E. coli that was unable to consume the sugar lactose and placed it in an environment where lactose was the only food source. They observed over time that mutations occurred within the colony at a rate that suggested the bacteria were overcoming their handicap by altering their own genes.
If bacteria that had overcome their own inability to consume lactose passed on this “learned” trait to future generations, it could be argued as a form of Lamarckism.
Finally, there is growing evidence that cells can activate low-fidelity DNA polymerases in times of stress to induce mutations. While this does not directly confer advantage to the organism on the organismal level, it makes sense at the gene-evolution level. While the acquisition of new genetic traits is random, and selection remains Darwinian, the active process of identifying the necessity to mutate is considered to be Lamarckian.
10.5.5 Lamarckism and Societal Change
Jean Molino (2000) has proposed that Lamarckian evolution may be accurately applied to cultural evolution. K. N. Laland and colleagues have recently suggested that human culture can be looked upon as an ecological niche like phenomena, where the effects of cultural niche construction are transmissible from one generation to the next.