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 Human Evolution is over |   Steve Jones, UCL's Department of Genetics, is claiming evolution is grinding to a halt. Fewer older fathers mean fewer mutated sperm-cells and therefore less variations in the offspring of the ancestor.
Every time there is a cell division, there is a chance of a mistake, a mutation. For a 29 year old father (average age of reproduction) there are around 300 mutations between the cells that made him to the one he passes on. Each one with an opportunity to make a mistake.
For a 50 year old father, that figure rises to well of a thousand mutation. Thus a drop in number of older fathers has a major effect on the rate of mutation.
'Our life expectancy is now so good that eliminating all accidents and disease would only raise it by two years." Steve Jones from UCL' Department of Genetics states.
Furthermore, natural selection is less of a factor.In ancient times, half the children died before the age of 20, leaving only the healthy and strong to live on. In the western world, now 98% of all children live past the age of 21.
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on August 29 2009 21:33:20
Somehow I don't think that guy's reasoning is all ok.
First off. Average age of 29 is quite high compared to ancient times - where the average life expectancy was a lot lower. To put it another way. There are far more older men having children today then before. Now by before I don't mean in the last 100 years, but in the last 10.000 years.
Then there is the case of natural selection. This is a toss up. Either you can view it like he does, or view it as more genes and more diversification. |
on August 30 2009 12:04:00
I agree partially with you in this. But his reasoning for 29, I think is that fathers kept on making children back in the old days, well over 50 too.
Nowadays, they tend to stop at 3-4 kids, which usually makes them have the last kid at 30-35, and probably the first at 20-25?
But I agree with him that if the genes don't have time to mutate, we will stop our evolution. He also states that with the integration of this world now, most people will become alike, with little differences (i.e. in race, genetic pools and the like). Which is quite scary to me! |
on August 30 2009 13:44:12
The fault lies with the "in the old days".
The mean life expectancy in the Roman empire (for which we have detailed census reports, and thus are able to calculate) was 25 years. Not a lot of older men got to have children. |
on August 31 2009 09:18:22
I did not copy and paste the text, so some misunderstandings may have occured.
A 50-year old maroccan (I think he was maroccan) allegedly had 288 children. That means 1.2 women every day in his adult life... |
on September 04 2009 08:40:24
How do you get 1,2 women per day, out of 288 children in 30 years (=10.950 days). I get that to be 38 days per woman for 30 years (assuming he started at age 20). |
on September 07 2009 11:23:42
haha, that's what you get for taking statistics for granted! Shame on me. |
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