This thread is intended to allow group members to issue responses to the essays I have written about evolution. Please state in the title window which essay you are referring to and then include your comments. I need feedback to ensure that my works are as accurate and understandable as possible.
Nice essays. I have read only 2 so far.
Firtsly, Evolution does not proceed backwards ... I don't think there really is a backwards or forwards in evolution. Actually there is - specialization. Some animals get highly specialised - often in a symbiotic relationship with other specialised animals. But specialization has a price - lack of versatility.
Anyway, whales don't have gills not because "evolution doesn't proceed backwards, as a rule". Evolution will choose the easier way. It was easier for ceateans to adapt the existing infrastructure.
There are species in transit. An example is our own species - a hunter by behavioural changes but with the body of an ape. Another is the panda - a vegetarian by compulsion.
I think what will illustrate this better is this:
When East Africa turned to grassland, species had two choices: evolve or become extinct. Now, the apes living there had bigger brains, they were smart, so they capitalised on that and became hunters by BEHAVIOUR. Humanoids. Baboons were not smart. They had to change their bodies. Now it has become increasingly common for baboons to hunt. It's a relatively new behaviour. And when they are chasing prey, you'll be amazed to see how much they are like wolves. They have a long snout, sharp teeth, run on all fours. Like dogs they start ripping prey right away. Changing their bodies was easier for them.
Sex and evolution: I think what needs to be mentioned is that in more powerful mammals, competing for mates isn't really violent. Violence is a last resort, they prefer rituals and ritualised conflict. If a species is to survive, it cannot go about killing its own kind. Those mammals that possessed lethal weapons and used them on their own kind are long extinct.
Actually, the male elephant seals are extremely violent towards each other, to the point that even some cows and baby seals may get crushed accidentally in the fights between the rival males. But that may indeed be a "worst case example".
This post was modified from its original form on 21 Aug, 17:41
Yeah - but see, they do not really possess any lethal weapons. Mice are really aggresive too. But tigers or elephants cannot afford to do that.
East Africa's natural history has been much misunderstood until the current decade. The old theories that bipedality, dexterity, brain development etc. were a result of disappearing woodlands becoming woodlands are now coming to be understood as overly simplistic and naive.
Most of human evolution took place in a wooded habitat. Physiology affected their diet far more than choice (any herbivores with teeth like ours?????), and brain size does not equate to intelligence (lest you are to believe yourself inferior to a robust australopithecine!).
Baboons are smart, but they are still mainly herbivores. Physiology, culture, learned behavior, and evolution need to be differentiated from one another before proposing a cause-effect relationship.
You seem to have this idea that, somehow, extinct animals are inferior to extant ones. That's a mistake. Usually, an extinction merely allows an inferior species to take advantage of a vacant natural niche. Why would mammals have remained so small throughout the dinosaurs' reign? Why are insects so small now?
Finally, the idea that animals are responsible for "changing" is a very Lamarckian evolutionary concept (i.e. the giraffe stretched its neck to get to the higher leaves on the trees). Baboons didn't change themselves (not that they've changed much at all over the last 5 million years or so), and neither did hominids. Nature changes them...by selecting those characteristics which enable an efficient, aggressive, or accompanied animal to outcompete (and, therefore, overproduce offspring) others vying for the same niche. Usually, this begins with one particular member of a species. However, isolation is vital.
Isolation is the key to speciation. Without an isolated population, evolution doesn't really happen. In East Africa, the cradle of mankind, isolation was provided by a whole lot of these babies:
Try reading one or two of my evolution essays and commenting on them next. As for your pics, I find that Internet Explorer 7 allows for a simply copy and paste of almost any pic from one website to here, but not directly from your computer to here. Do you have any Care2 photo albums?
Let me begin this critique by saying that Dale has presented a pretty good introduction to the idea of evolution, based on a passion for knowledge, and not formal biological evolution training. For this reason, we all need to understand that the (relatively) minor corrections or comments I have are presented in the interest of helping Dale to provide full and complete information, and not to take anything away from the great amount of time he has spent researching, compiling, and attempting to put into laymen's terms one of the most perplexing, misunderstood, and unfairly maligned scientific amalgams available.
1) Evolution is not a theory, but rather a "family" of theories. We term the "big picture" the modern evolutionary synthesis. Not only does it seek to explain the great variations between species, as pointed out by Dale, but also the striking similarities between them.
2) Dale's definitions of evolution are fine. But, if they don't work for you, maybe this will sum it up: "the changes in genetic traits within a population from generation to generation."
3) The concept of sexual selection is actually an important aspect of Natural Selection. The two other mechanisms are genetic drift and gene flow.
4) The key to passing heritable traits to offspring is variation. Variation is caused by "gene flow" (migrations between populations), "copy errors" in the process of cell reproduction, random changes in genetic material (mutation), and the exchange of genetic material between species. In bacteria, this exchange is called "horizontal transfer," while in plants and animals it is coined "hybridization."
5) I recommend to anyone who hopes to establish themselves as an authority on a topic that you would want to avoid "deciding" why someone might choose not to see the validity of a scientifically flawless construct. Along those lines, I feel this essay devoted far more time to baseless claims than those claims actually deserved. In other words, F*CK the fish guy!
6) Mutation - "their results are far more likely to weaken the resulting organism" (by a ratio of about 70:30). Mutations are caused by radiation, viruses, mutagenic chemicals, or transposition (DNA "filler" duplications). Also, errors in cell division can result in mutations. Sometimes, entire chromosomes may recombine or diverge for seemingly no reason.
7) Natural Selection relates an organism's "fitness" to its chances of survival and reproduction. The concept of "fitness" is not a static state. Environmental changes can stimulate, or devastate, an organism's chances at survival. If an allele improves chances for survival and heritability, that characteristic is "selected for." If it makes that organism less fit, then it is "selected against." Environmental changes can cause a trait that has been selected for to become selected against. Again, "fitness" fluctuates.
8) Changes in alleles that occur slowly over time, and in varied expressions, are considered to be "directionally" selective (the "big picture" tends to "evolve" in a particular "direction"). Changes that produce two highly competitive extremes, and therefore cause intermediate expressions of an allele to be "unfit", are termed "disruptively" selective (the "new" alleles "disrupt" the previous order of things away from the "norm"). Alleles that are most fit in their average expression, thereby making extreme characters "unfit", are considered to be selectively "stabilized," and tend to evolve away from variation (and sometimes toward extinction!).
9) "Either that, or the population itself will split in two, with one group having the new trait and the other not having it, and the two groups will begin to live apart, thus establishing a new species." This is the theory of Genetic Drift, basically.
All in all, Dale has provided a pretty good introduction to the concepts behind evolution. Each of the theories making up the construct (amalgam) that we consider the modern evolutionary synthesis warrants further study and research.
I recommend to anyone who hopes to establish themselves as an authority on a topic that you would want to avoid "deciding" why someone might choose not to see the validity of a scientifically flawless construct. Along those lines, I feel this essay devoted far more time to baseless claims than those claims actually deserved.
A lot of scientists who have written books and essays blasting Creationism would disagree with that assessment.