Evolution Gap - Where's the Fur?
thanks. will do.
Too true shepherdess.
Jacob, I'm new to this to a certain extent, but consider that the mating ball of snakes is most likely not actually 10k, simply because it could possibly be picked up by 10k snakes. In addition, this mating ritual continues with all female snakes of the breed. So it isn't a a matter of best snake gets the girl.....natural selection wins! It's a slow moving process over many many breeding cycles.
Regarding fur/hair, I'm actually most interested why we retain any. In particular as I approach my late 30's, why does it want to disappear from my head, and make its way to my earlobe?
Nature the science mag and PubMed great places to look for info
I agree with this, Simon
With natural selection, we're not deciding which thing *will* win, we have the results and know which one *did* win. So the race of the 1,000 snakes has already happened - there is no ordering them first, only after. Just like the winners in the Olympics are decided by who crosses the line first, not who the favourite is - but chances are the favourites (those best suited to the event) are most likely to win ... unless you make Michael Phelps compete in a different environment that he's less well suited for.
The question is about why a particular species survived and thrived and how it adapted and why some didn't. We see it today as species struggle due to climate change (even in the UK, certain songbirds are getting out of sync with the bugs they feed on for instance).
The environment changes and what was once a winning species suddenly struggles and somethings else adapts better to fill the gap.
one of my favourite theories has to do with the very rapid climate change and population changes in size that occurred in our history. In these scenarios, it seems, that genetic drift and genetic draft come into play more when population size falls and then when the population grows both positive and negative selection goes to work - here deleterious mutations may be weeded out or become fixed (but please read the article as my understanding may need refinement and I would be happy to be corrected). Of course as Simon mentions, it is afterwards that we can say whether or not a particular change in morphology (support for bipedalism for example) is beneficial and advantageous. so regarding having fur or losing most of it - it may be seen as a a loss or as a gain depending on which particular species one is making one's decision from.
Data collection re the genome has become more efficient now in the 21st century so I expect that we will be hearing more about these ideas. for what genetic drift and genetic draft mean please see the article I linked to.
okay here is the link - it seems to be available free of charge
re the above link here is the abstract
ABSTRACT Evolutionary biology has tended to focus on adaptive evolution by positive selection as the primum mobile of evolutionary trajectories in species while underestimating the importance of nonadaptive evolutionary processes. In this review, I describe evidence that suggests that primate and human evolution has been strongly influenced by nonadaptive processes, particularly random genetic drift and mutation. This is evidenced by three fundamental effects: a relative relaxation of selective constraints (i.e., purifying selection), a relative increase in the fixation of slightly deleterious mutations, and a general reduction in the efficacy of positive selection. These effects are observed in protein-coding, regulatory regions, and in gene expression data, as well as in an augmentation of fixation of large-scale mutations, including duplicated genes, mobile genetic elements, and nuclear mitochondrial DNA. The evidence suggests a general population-level explanation such as a reduction in effective population size (Ne). This would have tipped the balance between the evolutionary forces of natural selection and random genetic drift toward genetic drift for variants having small selective effects. After describing these proximate effects, I describe the potential consequences of these effects for primate and human evolution. For example, an increase in the fixation of slightly deleterious mutations could potentially have led to an increase in the fixation rate of compensatory mutations that act to suppress the effects of slightly deleterious substitutions. The potential consequences of compensatory evolution for the evolution of novel gene functions and in potentially confounding the detection of positively selected genes are explored. The consequences of the passive accumulation of large-scale genomic mutations by genetic drift are unclear, though evidence suggests that new gene copies as well as insertions of transposable elements into genes can potentially lead to adaptive phenotypes. Finally, because a decrease in selective constraint at the genetic level is expected to have effects at the morphological level, I review studies that compare rates of morphological change in various mammalian and island populations where Ne is reduced. Furthermore, I discuss evidence that suggests that craniofacial morphology in the Homo lineage has shifted from an evolutionary rate constrained by purifying selection toward a neutral evolutionary rate. Yrbk Phys Anthropol 53:13–45, 2010. VC 2010 Wiley-Liss, Inc.
And as per usual you are wrong, even worse you think that others understand as little about the subject as you do.
caedes aside from the playground insult does that mean you disagree then?
Yes, I disagree with your statement about natural selection looking strained. Simply stating that you are wrong or don't understand something isn't a playground insult. If I said that when talking about science you were the equivalent of a monkey with a typewriter then that would be a playground insult, but I prefer not to stoop to that kind of thing.
How often have paleontologists been lucky enough to find fossilized fur, anyway?