Lamarckism - Current Views

Current Views

Interest in Lamarckism has recently increased, as several studies in the field of epigenetics have highlighted the possible inheritance of behavioral traits acquired by the previous generation. A recent such study examined foraging behavior in chickens as a function of stress, concluding:

Our findings suggest that unpredictable food access caused seemingly adaptive responses in feeding behavior, which may have been transmitted to the offspring by means of epigenetic mechanisms, including regulation of immune genes. This may have prepared the offspring for coping with an unpredictable environment.... Transmissions of information across generations which does not involve traditional inheritance of DNA-sequence alleles is often referred to as soft inheritance or 'Lamarckian inheritance'.

The evolution of acquired characteristics has also been shown in human populations who have experienced starvation, resulting in altered gene function in both the starved population and their offspring. The process of DNA methylation is thought to be behind such changes.

In October 2010, further evidence linking food intake to traits inherited by the offspring were shown in a study of rats conducted by several Australian universities. The study strongly suggested that fathers can transfer a propensity for obesity to their daughters as a result of the fathers' food intake, and not their genetics (or specific genes), prior to the conception of the daughter. A "paternal high-fat diet" was shown to cause cell dysfunction in the daughter, which in turn led to obesity for the daughter.

Several historians have argued that Lamarck's name is linked somewhat unfairly to the theory that has come to bear his name, and that Lamarck deserves credit for being an influential early proponent of the concept of biological evolution, far more than for the mechanism of evolution, in which he simply followed the accepted wisdom of his time. Lamarck died 30 years before the first publication of Charles Darwin's Origin of Species. According to Stephen Jay Gould, if Lamarck had been aware of Darwin's proposed mechanism of natural selection, there is no reason to assume he would not have accepted it as a more likely alternative to his own mechanism. Note also that Darwin, like Lamarck, lacked a plausible alternative mechanism of inheritance - the particulate nature of inheritance was only observed by Gregor Mendel somewhat later, and published in 1866. Its full significance was not appreciated until the Modern evolutionary synthesis in the early 1920s. An important point in its favour at the time was that Lamarck's theory contained a mechanism describing how variation is maintained, which Darwin’s own theory lacked.

Several recent studies, one conducted by researchers at MIT and another by researchers at the Tufts University School of Medicine, have rekindled the debate once again. As reported in MIT's Technology Review in February 2009, "The effects of an animal's environment during adolescence can be passed down to future offspring ... The findings provide support for a 200-year-old theory of evolution that has been largely dismissed: Lamarckian evolution, which states that acquired characteristics can be passed on to offspring."

A report investigating the inheritance of resistance to viral infection in the nematode Caenorhabditis elegans suggests that small RNA molecules may be inherited in a non Mendelian fashion and provide resistance to infection.

Lamarckian elements also appear in the hologenome theory of evolution.