Remember the book Alice in Wonderland. So if you remember there is a character called the Red Queen. The Red Queen said, “It takes all the running you can do, to keep in the same place.”
The idea was Alice and the Red Queen were constantly running in the same place but getting nowhere. This concept can be applied to evolutionary fitness. Hypothesized by Lee Van Valen in
According to the hypothesis, there is a sort of evolutionary arms race. Selection pressures by organisms force other organisms to evolve to keep up, like host parasite, predator prey, ect. Sexual reproduction may allow for a species to evolve fast enough to maintain an ecological niche in their ecosystem.
This idea is relevant to immunology because the Red Queen hypothesis may explain the rate of evolution for genes in immunoglobulin and certain protein kinases. Think about the way we mix maternal and paternal genes HLA determination or MHC, or the hypervariable regions in immunoglobulin. Essentially sexual reproduction is worth the cost because of genetic variation, at least in some environments. Parasites and bacteria are constantly evolving to keep evade our drugs and so our genetic diversity may help us keep up with them. However there are some pitfalls to this hypothesis in immunology, we have not evolved fast enough to keep up with HIV or certain cancers.
http://www.factfixx.com/2011/12/06/the-red-queen-hypothesis/
Kuma, K.; Iwabe, N.; Miyata, T. (1995). "Functional constraints against variations on molecules from the tissue-level - slowly evolving brain-specific genes demonstrated by protein-kinase and immunoglobulin supergene families". Molecular Biology and Evolution 12 (1): 123–130. PMID 7877487
http://www.pbs.org/wgbh/evolution/library/01/5/l_015_03.html
I have honestly mostly thought about reproduction and evolution in the scope of genetic diseases, i.e. inbreeding and inheriting recessive disease. However, you are right, you can see signs of human immune evolution. Not just in Ig but also in basic organs like the human placenta. There is a molecule on human B-cells and the human placenta, Siglec-6, that has only also been seen in primates. However, in primates it is ONLY on their B cells! What is this immune related molecule doing on the human placenta? How did we evolve to possess this molecule on our placenta and how does it help us? I think it's amazing how quickly we evolve to meet our environmental and physiological demands!
ReplyDeleteMy specific area of research is related to evolutionary genetics and preterm birth. Nicely relates to the Red Queen hypothesis!!
ReplyDeleteIf we examine human birth from an anthropological perspective we find that the evolution of humans to be bipedal has resulted in a head-to-pelvis ratio unsurpassed by our primate counterparts. That is, human infant head circumference is severely disproportionate to the maternal pelvis, as compared to other primates.
The problem is cephalopelvic disproportion.
We also have a preterm birth issue...especially in the United States. But could the preterm birth problem actually be from evolutionary adaptation to accommodate earlier birth, and therefore smaller fetal head.
So you are asking, what evidence supports this idea?
Dr. Louis Muglia and Dr. Jovan Plunkett have dome some preliminary work in identifying genes responsible for labor initiation in humans, and tracing the evolution of those genes over time.
Specifically, African descendants are disproportionately affected by preterm birth, but have also demonstrated acceleration of genetic transmission of alleles for hypertonic uterus and uterine contractility.
Could the preterm birth problem be the human way of adapting to accommodate our bipedal society?
While the Red Queen theory purports genetic variation and population variation as it central tenant, is it also possible that there are links to current health "problems" that are actually or species way of preparing for the future?