Charles Darwin and biobanks: heredity and disease, part I

This post is about biobanks, a subject on which we've written several times in the past (e.g., here). We don't think much of biobanks in the context of genetic approaches to medicine and public health, for reasons that have to do with a proper understanding of how evolution works and of how genes affect variation in complex traits--that is, most traits.

This is manifestly not because disease isn't heritable!  It has to do with how human traits are inherited -- if you read this blog regularly, you've had read our argument before (but if not, last week's post on DTC genetic testing pretty much lays it out).  Concern about heritable disease is by no means new.  In a sense it traces back to the earliest medical writings, by Hippocrates and his group.  Their idea about inheritance was roughly the same as Lamarck's: physical changes that happen to you during life are transmitted directly to your offspring.

People well-enough educated and well-enough off to worry about whether or who to marry, or whether their children might not be healthy have been writing about this for centuries.  The concern extended to mental disorders ('madness'), or perhaps even focused on them.  One Mercatus wrote a treatise on the subject in the early 1600s, and a Dr Portal published a major work in France in 1808 on hereditary disease using various kinds of evidence available at a time when modern science was becoming a more central part of medicine.  Great concerns were raised about the risks of bearing affected children.

An Englishman, Joseph Adams, was upset by this frenzy of worry, and tried to lay out the principles of hereditary disease in his own book a few years later (1814).  Adams showed that many of Portal's fears were groundless.  And he had an evolutionary perspective that strikingly foreshadows Darwin's ideas 40 years later (see Ken's Evolutionary Anthropology article, "Joseph Adams in the Judgment of Paris").  For example, if disease was hereditary it most likely will have late onset, because natural selection (he didn't use the term, which didn't exist then) would remove such heredity from the population.  That is, if a disease struck before reproductive age, it wouldn't be passed on to later generations.

Jean Lamarck published his Zoological Philosophy in 1809, about the same time as Portal, showing the kinds of thoughts that were 'in the air' at the time in France.  Lamarck tried to explain the origin of the diverse species in life through natural processes, which required a theory of inheritance, and he echoed the long-standing idea that your nature is modified by experience, and those acquired characteristics are transmitted to your children.  It was only natural to think so.  And of the awful things, madness was one of the worst to bestow on your own children!

Adams provided one of the first attempts at a scientific analysis of hereditary disease (as Ken's article outlines).  But the details and differences in familial patterns were complex and perplexing to those who thought about them.  One of those who brooded in this way was Charles Darwin: "My dread is hereditary ill-health." and "The worst of my bugbears is hereditary weakness."

After his beloved daughter Annie died, but even more generally, Darwin worried about the transmission of disease. Could he have been a source of the problem that took Annie away?   In particular, he worried that cousin marriages were more likely to concentrate heritable effects and result in children with heritable diseases -- and he had married his cousin.  He held Lamarckian views about the nature of inheritance, even if he differed greatly about the nature of evolution (that's a separate topic, well-known, but beyond our scope here).  With such a view, how could someone not transmit their ills to their children?  It haunted Darwin considerably.

Darwin was a believer in observational data rather than hand-waving, and he felt that a clearer understanding of the actual patterns of inheritance of disease was needed.  He favored a suggestion that had been made in Britain at the time, to establish a national registry of consanguineous marriages to gather the needed data.  In the very last section of Descent of Man, he stated his advocacy of such a Victorian biobank and sneered at legislators who opposed the proposal as just "ignorant".

So why wouldn't we still benefit today from a national biobank to understand the nature of inherited disease, which is just what is being proposed and established in many countries?  It has to do partly with the politics and funding of health care and research.  But it has more to do with the fact that now, unlike in Darwin's time, we do know a lot about inheritance, and disease.  In a next post, we'll go into some interesting relevant aspects of Darwin's view,  and how the long shadow of its legacy might be misleading the present.