Genetics and regression toward the mean (Galton)?
I read the first application of this statistical model to Genetics by Francis Galton where he ascribes the variation in some inherited attribute to the ancestry of an individual (specifically height), however this was in the 19th century.
My question is, what do we know now about the underlying mechanism for regression in genetics? I.e. when we talk about the "mean" in Genetics, what is the "mean", the mean of the ancestry of the individual as Galton contended or something else?
- 9 years agoFavorite Answer
Sir Francis Galton was Darwin's cousin who developed his ideas on "eugenics" in 1865. The word "eugenics" comes from the Greek meaning, "good in birth" or "noble in heredity". He published his book in 1869 entitled "Hereditary Genius". His purposes for developing the idea however were hardly noble. "His stated goal was to improve the human, race by giving 'the more suitable races or strains of blood a better chance of prevailing speedily over the less suitable'". (Otto Scott, "Playing God", in Chalcedon Report, No.247, February 1986, pg.1) Hitler used Galton's ideas on Eugenics as a tool to exterminate the "inferior races" including in particular the Jews.
It was actually a Zoologist at Brown's University by the name of Herman Bumpus who, in 1898, conducted experiments in the ideas of "Regression Towards the Mean"; it is known as "Bumpus Sparrows". He conducted experiments on 136 sparrows he discovered nearly frozen during the winter of that same year. 72 survived while 64 died. He weighed them and took measurements of their overall length, wing span, beaks, skulls, humerus and femurs. "Comparing the statistics of the two groups, he found the measurements of the birds that survived were closer to the mean of the group than were those of the birds that died. This type of mortality, where extremes are eliminated, is referred to as 'balanced phenotype', or stabilizing selection'..Even today, 'Bumpus' Sparrows continue to be quoted in about five published scientific articles every year." (R. Milner Encyclopedia of Evolution, 1990, pg.61). Educational Psychologists use "regression towards the mean" as it has never been violated in any of their studies. Their studies have discovered that although some individuals will show aptitude in particular areas and excel at the intellectual level they have discovered that as a rule their descendants will generally regress back towards the mathematical average. Therefore, their can be no "molecules to man" evolution as everything tends to move backwards towards the average.
Variations within created kinds can occur producing a variety of species however there are boundaries that cannot be crossed that will not allow one kind of animal to evolve into a different kind of animal.