I was staggered by the results we got, said Dr Owens. When we decided to control for these factors, I wasnt expecting anything to come out of it. I thought, lets just run with the analysis. But there was a massive difference in the number of children born to families with a religious affiliation. Many of the Catholic twins we studied had an average family of five children, where other families were having only one or two children.
We also found that mothers with more education were typically having just one child at an older age. Their reproductive fitness was much lower than their peers who left school as early as possible. Again, and again, our analyses for these two factors came back with the same results.
The influence of religion and education in family size may seem an obvious finding - but what the scientists found really astonishing was that after controlling for these social factors, genetic changes were influencing the three life traits studied.
Even after we controlled for these social factors, there was still lots of genetically heritable genetic variation in the three life history traits. This is a really unexpected finding.
However, he cautions against linking this work with the possibility of a eugenic programme for selective human breeding.
Looking to the future, I would expect to pick up genetic changes within the ten generations (6) since industrialisation. However, what this work doesnt indicate or find, is a genetic marker for human reproduction - so you cant breed for early reproduction from our data. All the traits that we have examined are controlled by interactions between the environment and many genes.
The future work aims to understand more fully, the contribution psychological factors make, says Dr Owens. We also want to repeat our experiments using twins databases elsewhere, to really put our results in
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Contact: Taslima Khan
taslima.khan@ic.ac.uk
44-20-7594-6712
Imperial College London
22-Apr-2001