A reply to a question in an online interview got me thinking a bit more about the previous post, and in particular, about the Bach family.
The name means brook in German, but there were so many talented musicians among them that Bach also came to mean musician in some parts of Germany. In the past, the fact that the ability seemed to be inherited from the father along with the surname would have suggested that it was linked to the Y chromosome, which men pass on only to their sons. But there are very few genes on the Y, and none known to be linked to cognition, so the likelihood is that the Bach dynasty owed their patrilineal inheritance of musical ability to paternally expressed genes like those on chromosome 15 now implicated in music as explained in the previous post.
If so, this would be an epigenetic, rather than genetic effect because it is dependent on the expression of genes, rather than on their inheritance. Epigenetic effects in general have been hailed by some as rescuing Lamarckian inheritance of acquired characteristics from the rubbish dump of history, and if this were true, it would be truly revolutionary.
Or perhaps the word should be reactionary, because it would return our view of heredity to the Middle Ages and re-instate what, in an earlier post, I called photocopier heredity: the impossible proposition that DNA could copy the organism rather than the organism copying its DNA, which is what actually happens.
But you can understand the appeal of Lamarckism. According to Paul Kammerer (1880-1926), called by New York newspapers “the greatest biologist of the century” and the “second Darwin:” “We may assume that the deeds and thoughts of man may be passed on” to future generations, resulting in a “man sublime.” Indeed, he concluded that
If acquired characteristics cannot be passed on … then no true organic progress is possible. Man lives and suffers in vain. Whatever he might have acquired in the course of a lifetime dies with him. His children and his children’s children must ever and again start from the bottom.
When you mention Bach today, most people think of Johann Sebastian Bach (1685–1750). But as the family tree above shows, there is indeed evidence of some kind of true organic progress rather than children and children's children starting at the bottom again in the Bach dynasty. But it is not what you would predict on the basis of Lamarckism.
As the diagram shows, there were five male musicians descended from Johann Sebastian Bach, one of whom, Carl Philipp Emanuel Bach (1714– 1788), was much better known than his father in the eighteenth and earlier nineteenth century. Indeed, if Lamarckian inheritance of acquired characteristics is to be believed, this would have been fully justified because he would have inherited the skill of his father Johann Sebastian Bach to add to that of his grandfather and great-grandfather before him, not to mention other Bachs on his mother’s side of the family.
Inherited skills, in other words, should show a cumulative pattern: getting better all the ti-hi-ime in the words of the Beetles song. But the fact is that today Johann Sebastian and not Carl Philipp Emanuel—and certainly not his son, Johann Christoph Friedrich (1732–1795) nor even his grandson, Wilhelm Friedrich Ernst (1759–1845)—is rightly seen as the greatest of the Bach family of musicians.
And the same is true of other famous musicians. If musical ability is cumulatively heritable, why, if Wolfgang Amadeus Mozart was so much better a composer than his father, wasn’t Wolfgang’s son, Franz Xaver Mozart (1791–1844), better still? And why didn’t Wagner’s composer son, Siegfried Wagner (1869–1930) established at the family fortress at Bayreuth, go on to conquer the musical world even more sensationally than his father had before him if he inherited his father’s genius—not to mention that of his maternal grandfather, Franz Liszt (1811-86)? Even in maths, another highly heritable acquired skill, the Bernoulli family shows the same effect: the best mathematicians are not found as the last in line as Lamarckian inheritance would predict.
The greatest biologist of the century and the second Darwin was eventually exposed as a fraud who had forged the evidence for Lamarckism that he could not find in toads, and which certainly cannot be found in the Bachs, however you interpret the word. On the contrary, the Bach family is a paradigm of true epigenetic inheritance: paternally-active imprinting on chromosome 15—and/or something very like it. Of course, I am not claiming that these were the only genes that mattered, and cultural factors which made males the musicians were obviously also important. But I am proposing that paternal imprinted genes on chromosome 15 explain the inheritance of musical gifts in the Bach family much more plausibly than does Lamarckism.
Epigenesis, the expression of genes to produce the developed organism and the noun from which the adjective epigenetic is derived, gives the lie to the commonly held but fallacious belief that, because complex traits like musical genius involve the expression of hundreds or even thousands of genes, single or small numbers of genes cannot be important. As I explained in a previous post, single genes can and do play key roles in epigenesis by triggering cascades of other genes to produce the end result, the paradigmatic example being the gene that determines being male in mammals. Imprinted genes such as IGF2 work in much the same way, so it is by no means far-fetched to suggest that those on chromosome 15 could be doing the same where musical ability is concerned.