Re: [DIYbio] Re: Prospects of anti-aging research

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Indeed, there's lots more than just reproduction to human genetics.
For example, humans would have evolved with a community that is far
more extended-family-based than most modern western societies;
childrearing and labour were shared extensively among family members,
meaning that the survival of a person's genetic line could be affected
by their ability to provide for their close relatives even late in life.

This concept has been used to explain why humans undergo menopause, a
nearly unique event in the animal kingdom; why would an animal cease
being able to reproduce while still alive and healthy?
A) Because the risks of an unhealthy child are far higher, distracting
them from healthier offspring and relatives.
B) Because they *will* continue to have sex, because it's so important
to human pair bonding and family cohesion.

The real reason (probably) why nature doesn't bother selecting for
longevity is that beyond a certain level, it's no longer beneficial
simply because natural organisms tend to die of other things. Death by
aging and cancer would have been pretty uncommon if not for
antibiotics, hygeine and vaccines, the "big three" of human health
that have eradicated some of the most common forms of death in prior
centuries.

So, we're weird, and unusually long-lived already, but until recently
we'd hit our upper limit in terms of "required longevity to be
successful".

As to Telomerase and Cancer, Telomerase expression alone will not
cause cancer, however it allows other mutations to lead to cancers.
The absence of Telomerase activity in somatic cells is what creates
the "Hayflick Limit", where normal cells can only divide a finite
number of times before running out of Telomeres and losing critical
genetic information. This limit helps prevent mutations that lead to
uncontrolled growth and division from leading to malignant tumours and
other cancers. Providing telomerase to these cells removes the
hayflick limit, allowing cells to resume growth.

On 02/28/2013 01:25 PM, Reason wrote:
>> -----Original Message----- From: diybio@googlegroups.com
>> [mailto:diybio@googlegroups.com] On Behalf Of Andreas Sturm Sent:
>> Thursday, February 28, 2013 5:00 AM To: diybio@googlegroups.com
>> Subject: Re: [DIYbio] Re: Prospects of anti-aging research
>>
>> If it was that easy, I suppose evolution would have done it.
>>
>> Well, that not, too.
>>
>> Evolution just cares that you can be healthy for 25-30 years. By
>> that age humans had already children. So their genes were passed
>> ahead, and aging had no influence on evolution, so it was not
>> counter-selected...
>
> Humans are comparatively long-lived for their size as mammals,
> requiring something like the grandmother hypothesis to explain how
> selection continued to operate at older ages to create that state
> of affairs - such as by selecting for mechanisms of stem cell
> decline to balance increasing cancer risk.
>
> The "it's a simple change, so evolution should have done it" view
> fails for all species we can easily gene engineer. Mice, flies, and
> worms all have numerous single-gene changes that can extend life by
> 10% or more. In worms and flies there are single gene changes that
> extend life more greatly than calorie restriction. None of these
> changes have been selected for by evolutionary processes.
>
> In humans, should we expect there to be analogous single gene
> changes? Probably not by current thinking.
>
> http://www.fightaging.org/archives/2009/06/significant-single-gene-longevity
>
>
- -mutations-in-humans-what-are-the-odds.php
>
> The changing nature of the environment operates on timescales that
> are long in comparison to the lifespans of lower animals, but short
> in comparison to a human life span. So there are good evolutionary
> reasons to expect lower animals to have more plastic lifespans in
> their present genome (e.g. larger calorie restriction effects to
> better survive famines) and the potential for more plastic
> lifespans through genomic alterations. But that cuts both ways -
> shorter can be better from the point of view of natural selection.
>
> Reason
>

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