Saturday, 9 November 2013

"20 scientific facts seldom taught to students" critically reviewed #5 Lamarck and the inheritance of acquired characteristics

What is Collyer's fifth 'fact seldom taught to students? "Acquired characteristics cannot be inherited. For example, a one-armed man will not have one-armed children, as Lamarck's theory falsely assumed in order to account for evolution."  Secondary students are taught this fact, as I can attest as this was discussed at length in my textbook. Modern evolutionary biology is not Lamarckian. Collyer is greatly mistaken if he believes it is.
Outside of a tiny number of biologists such as the immunologist Ted Steele, practically all biologists do not regard the inheritance of acquired characteristics as being the mechanism of evolutionary change. I remember being taught this distinctly when I was studying biology at secondary school.

Douglas Futuyma’s standard text Evolution comments:

Lamarck argued that species differ from one another because they have different needs, and so use certain of their organs and appendages more than others. The more strongly exercised organs attract more of the "nervous fluid," which enlarges them, just as muscles become strengthened by work. Lamarck, like most people at the time, believed that sud1 alterations, acquired during an individual's lifetime, are inherited – a principle called inheritance of acquired characteristics. In the most famous example of Lamarck's theory, giraffes originally had short necks, but stretched their necks to reach foliage above them. Hence their necks were lengthened; longer necks were inherited, and over the course of generations, their necks got longer and longer. This could happen to any and all giraffes, so the entire species could have acquired longer necks because it was composed of individual organisms that changed during their lifetimes.

Lamarck's ideas had little impact during his lifetime, partly because they were criticized by respected zoologists, and partly because after the French Revolution, ideas issuing from France were considered suspect in most other countries. Lamarck's ideas of how evolution works were wrong, but he deserves credit for being the first to advance a coherent theory of evolution. (Emphasis mine) [1]

Lamarckian evolution versus Darwinian evolution. (Source; Futuyma (2005)

Collyer’s fifth point underlines in a particularly emphatic manner how ignorant he is of evolutionary biology when he claims that the non-inheritance of acquired characteristics is a ‘scientific fact seldom taught to students.’ It’s standard textbook material.

1. Futuyma D “Evolution” (2005 Sinauer Associates) p 5-6