Human Limits

I have done a couple of recent posts on the idea that practice (the so-called 10,000 hour rule) is more important than talent in reaching elite levels of performance.   The main conclusion from all of this is that practice can make most people really good at most things but talent (and also exposure to given activity) are required for truly exceptional levels of performance.  When the topic of talent comes up the assumption is that it is inherited from our parents and other ancestors.  This then leads to the idea that talent is genetic and that eventually genes that confer the chance for exceptional performance are out there waiting to be identified.
You can take the same general line of reasoning and apply it to things like height, weight, or even your risk of getting certain diseases like high blood pressure and diabetes that tend to “run in families”.

 

Let’s Start With Darwin

Charles Darwin’s ideas pre-date the concept of genes.  He made lots of observations about how animals vary from place to place and adapt to their environment.  One of fundamental ideas is that via the process of natural selection, animals and plants best suited to their environment are more likely to survive and reproduce.  This reproductive success is dependent on the transmission of key characteristics to the offspring which increase their odds of survival.   When this happens generation after generation certain composite traits called phenotypes emerge.

 

Galton is Next

After Darwin, his cousin Francis Galton came along and started to make statistical estimates of heritability for things like height and intelligence.  His observations showed a strong correlation between parents and offspring for many phenotypes and he commented that:

 

“I have no patience with the hypothesis occasionally expressed, and often implied, especially in tales written to teach children to be good, that babies are born pretty much alike, and that the sole agencies in creating differences between boy and boy, and man and man, are steady application and moral effort. It is in the most unqualified manner that I object to pretensions of natural equality. The experiences of the nursery, the school, the University, and of professional careers, are a chain of proofs to the contrary.”

 

Galton’s statistical work was later extended and amplified by Pearson and Fisher who are familiar to anyone who has ever taken a basic statistics class.  The figure below is from a paper by Fisher in 1919 showing his estimates of how height was inherited from parents and earlier ancestors.

 

 

The First Version of Genes

About the same time that the statisticians got busy the work of Gregor Mendel was rediscovered.  Mendel did breeding experiments with peas of different phenotypes and showed via so-called “laws of inheritance” how the various characteristics were transmitted from generation to generation.  None of his observations could be explained in a satisfactory way by earlier ideas about how phenotypes were transmitted from generation to generation.  In about 1909 Wilhelm Johannsen came up with the idea of both genotype and phenotype and:

 

“Johannsen’s most notable experiments concerned his so-called ‘pure lines’ of the self-fertile princess bean, Phaseolus vulgaris. Studying the progeny of self-fertilized plants, he selected the character of bean weight and found that both the lightest and the heaviest beans produced progeny with the same distribution of bean weights, i e they were genetically identical. He concluded that the variations in bean weight were due to environmental factors and he introduced the terms genotype (for the genetic constitution of an organism) and phenotype (for the characteristics of an organism that result from the interaction of its genotype with the environment). Johannsen favoured the view of de Vries that inheritance was determined by discrete particulate elements and abbreviated de Vries’s term ‘pangenes’ to ‘genes’.”

 

In this view we have the idea that genotype = phenotype with some modification by the environment.  It also explains why Fisher assumed his estimates of the heritability of height could be explained by this early definition of “what is a gene”.

 

Genes and Evolution

The ideas about the statistics of heritability, genes and the fossil record were then integrated in the 1930s and 40s into something called the “Modern Synthesis” of evolutionary biology:

 

“The synthesis, produced between 1936 and 1947, reflects the consensus about how evolution proceeds. The previous development of population genetics, between 1918 and 1932, was a stimulus, as it showed that Mendelian genetics was consistent with natural selection and gradual evolution. The synthesis is still, to a large extent, the current paradigm in evolutionary biology.”

 

The Changing Definition of a Gene

What happens next is that DNA is discovered and the more general version of a gene is replaced by one based on the idea that DNA is a “read only” genetic code and that has been oversimplified to infer that DNA = phenotype.  There is actually something called the “Central Dogma of Molecular Biology” that has been perhaps unwittingly over extrapolated to infer that DNA=phenotype.   The term “Central Dogma” also has a strangely medieval religious ring to it.

 

However, it turns out that the genome and the products coming from it are subject to all sorts of environmental influences and that the idea of a linear – one way street – transfer of information from gene to protein to phenotype is a gross over simplification.  There is even evidence that acquired characteristics can be inherited.  These newer ideas about what might be described as a more flexible genome also explain why it has been so hard to find discrete DNA snippets that fully or even mostly explain many things including the statistical estimates of heritability exceptional longevity, height, BMI, intelligence and the risk for many common diseases.

 

For those of you who want to take a deep dive into these issues the link below is to a lecture by Denis Noble who has argued for a far more nuanced view of how genetic information is converted into phenotypes and how this influences how phenotypes are inherited from one generation to the next.

 

 

 

 

Back to Talent

Many human characteristics including things that might be called talent have a high statistical probability of being inherited from our parents and ancestors.  When the pre DNA definition of gene is used, then it is pretty easy to think about a sort of non-specific genetic explanation for them.  However, when the DNA based definition of a gene is used it is hard to find discrete or obvious DNA based genetic explanations for most things.  So, don’t expect a blood test anytime soon that is going to tell you that your kids are can’t miss at anything, and even if they have all the “genetic” talent in the world will they get exposed to what they might be great at and will they be willing to practice both intelligently and relentlessly?  The author Aldous Huxley (Brave New World) who comes from a long multi-generation family line of exceptional achievers said:

 

“There is no substitute for talent. Industry and all its virtues are of no avail.”

 

On the other hand a standard concept from the sporting world is that you “can’t coach desire”.

Perhaps the truly elite performer in any endeavor needs to have it both ways.

 

Tags: gene, genes and evolution, talent

This entry was posted on Thursday, March 6th, 2014 at 4:54 am and is filed under Current Events, Research and Health. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.