As new, amazing discoveries in modern science are made every day, it seems like it is the most reliable source for all information. However, it turns out that currently genetic predictions made about height are still about ten times less accurate than Sir Francis Galton’s method of predicting height which he devised in the Victorian era, in 1886. Genetist, Yurii Aulchenko using a much more complex method of scanning people’s genomes was able to compare the modern method to Galton’s method.
Galton became heavily involved in Hereditary, Historiometry and Eugenics after seeing his cousin, Charles Darwin’s publication, “The Origin of Species”. His method simply, averages the height of a child’s parents and made adjustments on the height based on age and sex. With a correlation made between measured height and this predictor, about 40% of the heights are predicted correctly. Proving to be quite accurate compared to predictions made based on human genotypes.
In order to predict height using genotypes, Aulchenko’s team had to analyse 54 different genetic variants, which were linked to height for 5748 people. These 54 selected genotypes were linked to studies that showed they were mutations in the genetic structure which tall people tended to possess. Yet, based on people who carried these genes, the correlation between their measured height and the prediction with variations based on age and sex; only 4% of the sample was predicted accurately. This draws many questions as the two methods are testing the same thing, generally with the same basic principles. Do we currently know enough about the human genome? Were there enough genotypes picked, deemed to be related to height? The obvious answer is currently, no, as hypothetically if everything was known about the human genome Aulchenko’s method would predict height within 80% variance.
Unfortunately, gaining enough knowledge about the human genome will not be done for many years as most genetic variations do not have much to do with height. This is further complicated, as our genome around 20,000 to 25,000 protein-coding genes with over 3 billion DNA base pairs. For now, Sir Francis Galton’s 123 year old method is still the most accurate for children’s height prediction.
References
http://www.newscientist.com/article/dn16698-victorian-rule-of-thumb-beats-genetic-prediction.html
http://scienceblogs.com/geneticfuture/2009/03/predicting_height_the_victoria.php
http://www.galtoninstitute.org.uk/Newsletters/GINL9912/francis_galton.htm
http://www.galton.org/
http://www.genome.gov/Pages/Education/AllAbouttheHumanGenomeProject/GuidetoYourGenome07.pdf
