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Insects May Have Had a Hand In Dinosaur Extinction
eldavojohn writes "Everyone's got their favorite theories of Dinosaur extinction, but new speculation is rampant in a book that gives cause to believe it may have been disease-carrying insects. Due to the length of their slow and eventual extinction (the 'K-T Boundary'), it is argued that this would more likely be attributed to the spread of disease and the rise of parasitic insects like ticks or biting flies. Are our immune systems the only reason any animals survived?"
Reptiles have perfectly good immune systems: in the case of alligators, they're better than human ones. However, since reptiles are cold-blooded, the seasonal temperature variation means reptiles have suppressed immune function during cold periods, so they'd be predisposed to higher mortality from disease after a meteorite strike or extensive volcanic activity puts enough debris in the atmosphere to reduce the Earth's temperature.
The Black Death spread across Europe and the Mideast in less than 4 years -- individual diseases can move very quickly. The idea that the rise of a class of disease vectors, biting insects, might've gradually led to higher mortality, is interesting, and something I'd never read about.
Nostalgia's not what it used to be.
"Incest May Have Had a Hand In Dinosaur Extinction" and giggled myself silly.
For the last time, we did NOT evolve from monkeys!!!
Monkeys and humans share the same ancestor - thats all.
You mean like how fleas carrying the plague made rats and humans extinct during the dark ages?
IIRC insects predate dinasaurs. Sorry, I'm a skep tick.
The book's author isn't a palentologist, he is with the Department of Entomology at Oregon State University. He is (like I am now) making claims he does not have the credentials for.
mcgrew's razor: Never attribute to stupidity that which can be explained by greedy self-interest
Uh, the species of rat which carried the Black Death did very nearly go extinct, and it wiped out one third of the population of Europe in just two years, in some areas as much as 60-75%. If that had been combined that with other pressures occurring simultaneously, like extreme changes in the environment, then yes, even two of evolution's greatest generalists could have been brought low.
I can't say I believe it, but I also don't find it inherently implausible.
The enemies of Democracy are
Antibacterial != antiviral. Their immune systems are very good at protecting against bacterial infection in those environments (and some reptiles, like the kimodo dragon actually have nasty bacteria living in their saliva that acts as a natural poison to weaken prey) but viral immunology is completely different. And viral mutations can move quickly though a population where they were previously benign.
Allow me to repeat something that has been said before:
Dinosaurs were not a tightly knit group, they were widely divergent. Any cause for the extinction must account for mosasaurs, elasmosaurs, icthyosaurs, pterasaurs and many mammalian groups as well. Plague by insect ain't that cause. For what it's worth, my degree is biology with specialization in entomology.
Reptiles have immune systems which work for them. They are cold blooded as was mentioned above. Reptiles (in general) have specialized cells which do phagocytosis (even very primitive organisms have this), lymphoid tissue (gut-associated etc) but not lymph nodes, lyphocytes differentiated into B cells and T cells. What they don't have is the variety of immunoglobulin classes that mammals have. ie Their antibody is IgM-like and IgG-like (IgY), but not IgD, IgE and class switching is either slow or non-existent. Birds were the first (phylogenetically) to exhibit lymph nodes and multiple Ig classes, and class switching. Furthermore reptiles don't seem to be able to do the memory (amnestic response) very well. To say that the reptile system is better (or as good as) the mammalian system is non-sensical. They both work have worked to keep species alive for many millions of years and they both continue to evolve. The key is that they work for each in their own envirnmoment. The immune system of a cold blooded animal is by necessity different from a warm blooded animal because bacteria have adapted to grown so much faster at warmer temperatures. If the immune system cannot respond rapidly (ie memory response) then that individual dies. If you look at the evolution of the immune response it appears to have taken several leaps rather than evolving gradually and steadily. These events coincide with changes which could alter the microbiological pressure on animal species. (see the Silurian period and the development of immunoglobulin and T-cell receptors, also the important RAG 1 and RAG2 genes). If reptiles were evolving into birds and there was a change from cold-blooded to warm-blooded at the same time you would expect to see a shift in the immune system capabilities --- and we do. Insects, while vectors of disease likely had little to do with this shift (Achem's razor) http://www2.ncseweb.org/kvd/exhibits/immune/immune_evo_annotated_bib.html