We evolved in a dangerous environment, the African savanna. Therefore there is no natural selection for genes that benefit us in our old age, but there is strong selection for the genes that give us the ability to survive danger. For example, if a mutation can help us stay alive but it will cause problems when we are in our sixties or seventies, then it will be beneficial, because most of our ancestors never lived to that age.
Take the gene for male pattern baldness for example. It codes for an excess of DHT or Di-hydro-testosterone. An excess amount of DHT will cause an increase in facial and body hair. In a cold climate, these traits would be beneficial and keep us warm. A person with the baldness gene living in northern Europe has an advantage in needing less clothing to stay warm, and may not freeze to death as easily when a bad snow storm strikes. However, excess DHT can cause male pattern baldness, and that may make the person look senile, and may affect his ability to find a mate (few young women are attracted to old men, and baldness is often associated with old age), but male pattern baldness generally do not appear until after 30 years of age, long past the time most prehistoric people had found mates. Excess DHT also causes prostate cancer in old men, but if few people lived old enough to develop prostate cancer, then what difference does it make? That is why a gene like the male pattern baldness gene can increase in frequency (25% of men in the US are carriers) even though it may have negative impacts on the body in old age.
Since humans have not been expected to live past the age of 60 throughout our evolutionary history, genetic mutations that negatively impact old people but benefit us when we are young can become part of our genome.
Take the gene for male pattern baldness for example. It codes for an excess of DHT or Di-hydro-testosterone. An excess amount of DHT will cause an increase in facial and body hair. In a cold climate, these traits would be beneficial and keep us warm. A person with the baldness gene living in northern Europe has an advantage in needing less clothing to stay warm, and may not freeze to death as easily when a bad snow storm strikes. However, excess DHT can cause male pattern baldness, and that may make the person look senile, and may affect his ability to find a mate (few young women are attracted to old men, and baldness is often associated with old age), but male pattern baldness generally do not appear until after 30 years of age, long past the time most prehistoric people had found mates. Excess DHT also causes prostate cancer in old men, but if few people lived old enough to develop prostate cancer, then what difference does it make? That is why a gene like the male pattern baldness gene can increase in frequency (25% of men in the US are carriers) even though it may have negative impacts on the body in old age.
Since humans have not been expected to live past the age of 60 throughout our evolutionary history, genetic mutations that negatively impact old people but benefit us when we are young can become part of our genome.
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Ok, i don't really know for sure the reason why, I guess it's to prevent certain things*(God knows what), but I do know How...When sugar is oxidized in your mitochondria, the unneeded oxygen is released as a waste in an unstable form known as a free radical which can actually oxidize or break down your cells, mostly the mitochondria and cause organs to fail, including the largest organ(the skin).
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Because we have telomeres at the ends of our chromosomes. When our DNA is copied we lose a little piece of those telomeres. After time we lose so much off the ends of our chromosomes that our bodies break down. This is why we age.
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??? EVERYTHING ages...it just depends on when you got it or when you were born...wtf? And plus we all have to get old and die because if we didn't there would be a WHOLE lot of people. So, everything ages...
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Humans get born, then die..then the new generation arises. That's the circle of life..
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All things age. It's part of the life cycle. Born, Live, Die.
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It's part of living....if no one aged and died it would be pretty crowded by now.
Our cells start to die out..it's part of the rhythm of life
Our cells start to die out..it's part of the rhythm of life