Giraffes

'Don't pull that face, if the wind changes direction you'll stay like that.' 

My mother was not superstitious but would happily engage any tool at her disposal for a colourful admonishment.  I didn't believe the threat, but the saying reflects the widely held notion that the environment can mould nature.  The idea that giraffes developed long necks as a result of their parents stretching to reach leaves on high branches was advocated by Lamarck who preceded Darwin.  Experiments have established that this is not how evolution works.  The impact of the environment is restricted to favouring or disadvantaging mutations which have arisen at random, not generating them in the first place.

In the 1930s, the Soviet agronomist Lysenko increased wheat yields by exposing seeds to high humidity and low temperature.  Crucially he claimed that this treatment would also improve the plants' descendants; in other words, that acquired characteristics could be inherited, just as Lamarck had suggested.  His work appealed to the communist party who were desperate to maximise grain production.  Eventually his theories were the only ones permitted.  All over the eastern bloc and in China Lysenkoism became the orthodoxy; geneticists who challenged it were silenced, imprisoned or executed.  But Lysenko's experimental data were faked and by the 1960s his ideas had been largely discredited.  As a biochemistry undergraduate in the 1970s, I was taught that the notion that the environment could influence genetics was preposterous. 

In a strange reversal, modern molecular biology has shown that DNA can indeed be modified by environmental factors.  So although you can't change the genes you're born with, those genes can be altered.  These modifications don't affect the content of the DNA, they simply change the way in which the information is expressed, for example causing some sections to be ignored.  It's a bit like clicking the 'save for later' option at the Amazon checkout: the request is still there but dormant so the delivery centre knows not to act upon it.  Even more significantly, in some cases, the changes wrought by the environment can be passed to offspring; the study of this phenomenon is the infant science of epigenetics.  A project which has been tracking a group of families since the early 1990s has shown that children of mothers who smoked in pregnancy carry DNA markers associated with their mothers' habit.

The implications are immense.  People know that their lifestyles can impact their own health and choose whether sacrificing a pleasure is justified by the benefits.  Dame Sally Davies apparently considers the increased cancer risk every time she fancies a glass of wine.  But such decisions might play out differently if the result is known to impact yet to be conceived children.  Possibly the progeny of feckless parents whose lifestyle has resulted in suboptimal DNA might seek redress in the Courts.  Perhaps couples will elect to have their families sooner so they can commence a life of debauchery without damaging their children's DNA, or maybe they will simply freeze their pristine eggs and sperm for later procreation.

© David Thompson 2016