Category: Biology
Posted by: Aaron
Many complex systems are homeostatic (aka autopoietic aka self-maintaining). Such systems are, by their nature, resistant to change because they contain mechanisms to return system dynamics to a particular pattern. However it is not the case that such systems only have one possible self-maintaining pattern. If a homeostatic system receives a large enough perturbation then the system may settle to a different pattern. We would expect that as a homeostatic system experiences a series of shocks it would spend a much greater amount of time in each homeostatic pattern compared to the transition time between patterns. That is precisely the phenomena called punctuated equilibria.

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Category: Biology
Posted by: Aaron
It occurs to me that since the body has natural mechanisms to deal with cancerous cells, and since we only find cancers (in people) when they are large and intrusive, research into preventative measures for cancer is missing data on the features of those cancers that the body can fight. That information could be very helpful if we could impinge those features of cancers that our body can deal with on those cancers that we can't yet deal with. That is, it might be easier to trick faulty cells of ours to act like other faulty cells of ours (that can be dealt with by our immune response) than to attack the cancer with external and alien means. The hard question of course is how to find cancerous cells that the body is already successfully battling since they don't produce symptoms and won't last long.

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Category: Biology
Posted by: Aaron
A recent study published in PLoS Biology reveals that so-called "identical" (monozygotic) twins are not completely genetically identical. Visible differences in phenotype (such as height, freckles, etc.) have hinted to differences, so have difference in disease susceptibility, but researchers couldn't eliminate purely environmental factors as the cause. This recent work definitively shows that there are genetic differences, specifically with the number of copies of genes. Because the twins start from the same cell, they must have started genetically identical. So something in the environment during development must explain the deviation in the genes. A person's genes change over time. That's supposed to be a radical idea, but perhaps because I am not deeply steeped in the dogma of this research field for me this is pretty obvious. It's quite easy to hypothesize several plausible mechanisms through which this happens and that's what I'll do here.

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Category: Biology
Posted by: Aaron
In recent decades the idea of group selection has gotten a bad rap. In 1871 Darwin outlined what he considered to be the conditions of group selection in terms of self-sacrificing tribal warriors that do not further their own reproductive fitness through their sacrifice, but acting in such a way provides benefits to the tribes that encourage such behavior over those that do not. And these benefits can be cashed out in terms of tribes being able to better compete for resources against other tribes and hence spread more readily across the landscape…we might call this "social selection". From a complex systems standpoint the idea of social selection seems pretty intuitive; it's just regular natural selection where social groups are the agents of a larger system. So what's the trouble?

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