“Selection” lies in the begetting and evolution is just a result

Recently I posted about two  papers by Gerald Crabtree who suggested that perhaps human intelligence peaked as hunter-gatherers, and

“that we are losing our intellectual and emotional capabilities because the intricate web of genes endowing us with our brain power is particularly susceptible to mutations and that these mutations are not being selected against in our modern society”.

Apparently it is not politically correct to suggest that humanity might be on a “degenerative” evolutionary path for intelligence and Crabtree’s speculations have been the subject of indignant criticism:

Why Gerald Crabtree’s speculations about declining human intelligence are wrong: ….  But like Sanford, Crabtree fails to analyse the problem correctly. In particular, neither show any understanding of quantitative genetics (this is the area of genetics that deals with lots of genes acting on a trait). But unlike young earth creationist Sanford, Crabtree doesn’t even bother to present any data to indicate that an intellectual decline has actually happened.

Discussions and arguments about “intelligence and race” or the “future evolution of intelligence”  or “what intelligence is” or whether “intelligence is selected by natural selection” are fascinating but – in evolutionary terms – are largely irrelevant. Evolution is not a force of change. It is the consequences of a response to change, a result – a report-card of what has happened before.

What counts for evolution – both for what has happened before and for what will happen in the future –  is which inheritable traits lead to the most begetting. It is in the begetting of offspring that all “selection” lies. This applies both with natural and with artificial selection. All other traits which happen to be present in the individual organisms being reproduced and which are inheritable are only carried along with the ride.

The dumbest person alive today has been just as successful in evolutionary terms as the most intelligent person. In terms of their evolutionary past, Bill Gates or a Nobel laureate or an Olympic gold medalist are genetically equivalent to the most wretched slum inhabitants in India or Brazil. They have all journeyed for some 4 billion years and have managed to reach the present. As have all the 7 billion other humans and also every other organism alive today. In terms of their evolutionary future it depends only upon which individual will have the most descendants! The sperm donor who is said to have fathered some 600 children in the UK could well be the person who will have the most number of descendants in the future. A modern day Genghis Khan effect!

Whether “intelligence” – however it is defined – is an inheritable trait is still a matter of some conjecture. Whether the trait – in the past – has ever been “selected” is also uncertain and depends on whether it ever led – directly or indirectly – to a greater level of the begetting of offspring.  And even if it was once “selected” for, it does seem that it is less likely to be a direct arbiter of “selection” in modern societies. It seems likely that there is some trait which we can label “intelligence” but which does not directly lead to the greater reproduction of offspring. It is one which is carried along by those that do. Regarding the future “evolution” of this trait called intelligence

….   it is only a matter of simple arithmetic that unless the “more intelligent” reproduce at a higher rate than those of “less intelligence” then the “average intelligence” of the population will inevitably decrease.

Related:

The evolution of intelligence

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