Thursday, November 01, 2007

alergy sufferers!

Another role played by the immune system is to destroy malignant tumours before they take hold—and work carried out recently by Annette Wigertz of the Karolinska Institute, in Stockholm, and her colleagues suggests that the immune systems of those with allergies may be particularly good at this. However, in a nice example of the way that one set of data is sometimes capable of divergent—indeed, opposite—interpretations, she may instead have discovered a clue about how cancers shut down immune systems in order that they themselves may prosper. (economist)

9 comments:

Pierre said...

I've wondered... if cancers are caused by external agents (carcinogens), could they be homo sapiens' attempts at adapting to our environment?

After all, (at least according to Darwin!) animals adapt physiological/ genetic modifications to suit their environment...

Except, as in the case of cancers, homo sapiens is still going through the trial and error phase of creating new physiological/ genetic adaptations...

Nirmalan said...

Mmm Pierre - i doubt it - basically because we can't transfer cancers to our progeny. they're not changes to our dna in our sex cells (ova or sperm), so they can't be transferred. instead they just hurt lots. As for cancers in general, my immune system better be darned good at stopping them coz I'd hate to find out i had to go through several years of god-damned hayfever and then ALSO got cancer.

Pierre said...

I'm not a scientist by any means (other than curiosity).. but the risk of particular kinds of cancers is higher if a parent suffered from them...

It could also be because the child might logically be exposed to a similar environment than the parent and have the same genetic responses to the carcinogens?

Presumably that risk is also reduced if the child changes the kind of environment they're exposed to??

any oncologists/ evolutionary theorists/ intelligent designers out there?

Jesse said...

my colleagues at the Kyoto University graduate school of medicine, Zhao-Zhu Zeng, Shin Higashi et al, have found that they can develop genetic resistance in rats to a type of liver cancer produced by a known carcinogen. here is their lovely paper

Nirmalan said...

Wow - and only 8 pages too, excluding footnotes! Will have to rad that now :)

On the point of evolution though - been long time since i touched biology, but there's two ways of looking at it I think. On the one hand (and this is what you guys are talking about I think), you can have people in a population with pre-existing genes that predispose them to particular illnesses, or protect them more than most against particular things. This is like with sickle cells in malaria-affected countries. Then when the disease they're stronger aginst than everyone else hits, it weeds out those who are particularly weak against it, and increases the population of the people who are relatively stronga against the disease. So the population evolves to have more people with the beneficial characteristic. The other type of evolution (which is waht I was talking about) is where the genes in your body mutate and evolve over time to produce new results taht aren't previously in the population. That takes a very long time, is entirely random, and any changes must be in teh sex cells to be passed on to offspring and allow for evolution. It introduces new characteristics into the population gene pool that may one day come to dominate a population gene pool.

Jesse said...

this is a good point, nirmalan. i think both "types" of evolution that you mention are the same, just with different reference points in time. people have lactose tolerance and sickle cells "already", but it took thousands of years, let's say.

still obeying this fact, we can say this about rats:
-rats reproduce quickly, and we can control their reproduction so that there is artificial selection instead of natural selection, making genetic changes pronounced quickly.
-carcinogens cause cancer, but perhaps they also cause mutations. these mutations will happen on a shorter time scale than random mutations.

of course, it is unethical to artificially control human breeding, and industrialization and large-scale chemical manufacturing has only been with us for about five generations. in other words, carcinogens will always be dangerous because they arise too quickly to ever be adapted to.

Jesse said...

this is a good point, nirmalan. i think both "types" of evolution that you mention are the same, just with different reference points in time. people have lactose tolerance and sickle cells "already", but it took thousands of years, let's say.

still obeying this fact, we can say this about rats:
-rats reproduce quickly, and we can control their reproduction so that there is artificial selection instead of natural selection, making genetic changes pronounced quickly.
-carcinogens cause cancer, but perhaps they also cause mutations. these mutations will happen on a shorter time scale than random mutations.

of course, it is unethical to artificially control human breeding, and industrialization and large-scale chemical manufacturing has only been with us for about five generations. in other words, carcinogens will always be dangerous because they arise too quickly to ever be adapted to.

Jesse said...

this is a good point, nirmalan. i think both "types" of evolution that you mention are the same, just with different reference points in time. people have lactose tolerance and sickle cells "already", but it took thousands of years, let's say.

still obeying this fact, we can say this about rats:
-rats reproduce quickly, and we can control their reproduction so that there is artificial selection instead of natural selection, making genetic changes pronounced quickly.
-carcinogens cause cancer, but perhaps they also cause mutations. these mutations will happen on a shorter time scale than random mutations.

of course, it is unethical to artificially control human breeding, and industrialization and large-scale chemical manufacturing has only been with us for about five generations. in other words, carcinogens will always be dangerous because they arise too quickly to ever be adapted to.

Dody G. said...

A culture that trains its young people to procreate only with one another becomes, over time, a genetically distinct population. And if that culture glorifies intelligence to such a degree that it drives less intelligent people out of the community—or prevents them from attracting mates—it becomes an IQ machine. Cultural selection replaces natural selection. For example, Jews have long emphasized male literacy. For this reason, Murray argued, anyone who was Jewish and stupid 2,000 years ago found "it was a lot easier to be a Christian." Entine called this kind of process a "bio-cultural feedback loop."

http://www.slate.com/id/2177228/