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This review is from: Survival of the Sickest: A Medical Maverick Discovers Why We Need Disease (Hardcover)
This book about genetics, evolution and disease is a genuine page turner, that's how deeply interesting it is, and how well it is written. The basic premise runs like this: The environment puts pressure on all living things, including humans, to evolve characteristics that help us survive long enough to reproduce and pass on our genes. Over the millenia, various conditions such as drought, ice ages and other climate changes have sparked genetic mutations that enhance our abilities to survive. These include some biological conditions that are advantageous in the short term, but sometimes detrimental in the long term.
For example, today we consider diabetes mellitus a serious disease because it raises human blood sugars to dangerous levels that can result in loss of limbs and sight, among other problems. However, in an ice age, when temperatures were significantly lower than they are now, having extra sugar in the blood may have enabled our ancestors to survive the cold because sugar lowers the temperature at which we freeze to death. Similarly, Sickle Cell Anemia may have evolved to help people resist malaria.
What's especially interesting is that this theory would explain why ethnic groups that are prone to diabetes -- Scandinavians and people from the British Isles, for instance -- originally came from northern areas that were at one time covered by glaciers. And the ancestors of those groups that tend to carry the genes for Sickle Cell generally originated from climates in which malaria was prevalent.
Another intriguing idea is that some "sicknesses" only become serious problems when an individual is older and past his or her prime reproductive years. So if one of our ancestors had, for instance, a chronic disease like diabetes, it probably wouldn't kill him/her until after the person had children.
There are many such fascinating observations and facts in this relatively short book and I highly recommend it to anyone who wonders how things and people got to be the way they, and we, are today.
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Showing 1-5 of 5 posts in this discussion
Initial post: Apr 29, 2007 5:21:49 AM PDT
T. A. Moats says:
If I remember my college evolution class correctly, you, unfortunately, have made a very common mistake regarding evolution, mutation, adaptation, and environment. Environment DOES NOT cause an organism to mutate. Mutations happen randomly. Accidentally, if you will. That mutation allows the organism to survive while the others die. That mutation is "selected." That species (assuming the mutation is not so great to create a whole new species) now has the genetics to continue (i.e. reproduce). In short that species has adapted to the environment. But as I said, the environment DID NOT cause the mutation. I think that confusion comes because human beings are self-aware of their existence (that's a whole other conversation). Organisms, such as human beings can adapt to their environment, but it is a conscious adaptation. Evolution is not a conscious change made by an organism.
In reply to an earlier post on Jun 18, 2007 11:49:26 AM PDT
Gaetan Lion says:
I am sure you are right. But, natural selection is not so random. Mutated genes that have mutated randomly as you explain will either be part of an individual that survives change in environment or not.
So, even though mutations do happen randomly they are naturally selected not so randomly due to change in the environment.
In view of the above, streamlining all the technical semantics aside is the shorthand "the environment causes genetic mutation" so wrong once you map out the whole process and the end result?
In reply to an earlier post on Mar 12, 2008 9:04:53 AM PDT
Allison Matus says:
Yes, it is. Selecting a particular mutation and causing the mutation to happen in the first place are two very different things.
In reply to an earlier post on Jun 30, 2012 9:58:07 AM PDT
I think Moate and Lion are talking about two separate things. Both can occur simultaneously. Take the example of the Peppered moth in Britain during the Industrial Revolution. The normal phenotype expression of these moths can either be a light grey with black flecks or a charcoal black. Historically the grey were predominate because they had better camouflage against the light tree bark where as the black moths were easy prey for birds. However, as the Industrial Revolution causes pollution to cover the countryside in soot, the black moths had better camouflage and the levels shifted so now the black were more likely to live long enough to reproduce. That is an example of environmentally determined evolution. However, Moate is also correct in that mutations are mistakes. Transcription or divisional errors that are made without any intention on outcome. Most errors probably result in death, but every once in a while the outcome of an error will cause an effect that will be beneficial to the organism resulting in increase lifespan and breeding.
In reply to an earlier post on Jul 8, 2012 8:27:00 AM PDT
B. McEwan says:
Thanks for your comments, Colleen. Great points.
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