ufology said:
You say evolution doesn't always move extremely slowly ... that's a switch from typical skeptical arguments because I've heard the "glacially slow" process of evolution described more than once to explain why evolution makes more sense than creation.
You heard wrong and your reference is 200 years out of date (which makes me wonder how out of date the rest of your sources are...). Sorry to be so blunt, but that's the simple truth of the matter. Evolution moves slowly IN HUMAN TERMS. But you, as is the case for the majority of people, appear to have no concept of how long a million years is (this is no insult--humans didn't evolve to understand things like this, and it takes a while for geologists to really wrap their heads around it). Again, a new species can arise in 10,000 generations (as demonstrated by Gould and Eldredge). Assuming a new generation every 20 years in humans, that's 50,000 speciation events (assuming they happen one after another, that is). Even in evolutionary terms a million years is A LONG, LONG TIME. A whole lot more tweaks can accumulate in that period of time than can species (by definition, this must be the case--paleontologists utilize the morphospecies concept). When dealing with a taxa that's radiating like crazy, which is what the human family was doing, one million can very well be several species' worth of time, and an even GREATER accumulation of tweaks is possible. Read up on the modern take on evolution--and particularly punctuated equlibrium--if you want to discuss the tempo of evolution.
FYI, the average lifespan for a species is roughly 4 to 5 million years. Which means that 1,000,000 years is roughly 1/4 of the entire lifespan of your average species. Not exactly a short period of time.
We aren't talking about changing the species. We're talking about explaining how our brain size changed so dramatically in such a short evolutionary time span.
Which is an even smaller shift--again, by definition (if you're talking fossils, you're talking morphospecies--which are defined by the alteration of individual traits to the point where you can call it a new species [clunky, I know, but that's the gist of it]). You're talking about a shift in the size of a single organ--hardly an enormous evolutionary event, particularly when you consider all the OTHER changes going on at the time (ever hear of Nutcracker Man? How about the hobbits?). There are all kinds of genes which can play havoc with the size of organs, one of which you've specifically pointed out.
Please don't start with the informal insults.
I called your idea crackpot because it is--it's flagrantly false, it reveals a complete lack of understanding of the basics of the field in question, and it's so easy to prove wrong (like I did with the link). It's not an insult, it's an assessment.
I've read several articles and a couple of books about brain evolution that don't explain the jump in brain size through any fossil records,
I'm sorry, but for a question of this magnitude that's not even a start (I'd be less hostile if you hadn't jumped in with aliens and the like). When I start any research I read as much as I can on the topic--I'll read "several articles and a couple of books" just to start the list of references I need to track down. And again, you're artificially limiting your research, which is giving this event far more importance than it should really have (while masking the REAL question). If you look for brain size in the human family over time, you find that it shows a pretty nice geometric curve.
Look at the second figure (labeled Figure 4 thanks to coming from a publication) at this link. (I haven't read the whole link, but I HAVE read the paper this is from, and the data are sound, even if the interpretation of the link is off.) Brain size increases slowly, then takes off like a rocket. Seen in that context the question isn't "Why did human brains increase so rapidly at one point in time?" but rather "Why is the rate of brain size increase increasing with time?"
The reason this invalidates your original question is that it implies (as strongly as the data you are looking at implies your conclusion) that the mechanism involved started much, much earlier than you assumed and that it's ongoing (or at least was up until so recently that we don't have the resolution to see that it's stopped). We're not looking for a single, isolated event that increased brain size--we're looking for something far more systematic, over a vastly greater scale, generating a geometricly increasing brain size through various species of humans. And this opens the question of whether the selection pressure is increasing, or if perhaps the movement from low-lying portions of morphospace to local highs is more complex than we thought. At any rate it certainly proves that the "jump" in brain size 1) does not, in fact, exist and 2) isn't really an isolated event at any rate.
We aren't talking about ape brains.
Oh? So humans aren't apes?
Our brains ARE ape brains because WE ARE APES. And orangutan brains are relevant because increases in size don't necessarily reflect increases in ability, intelligence, or anything else that matters to this discussion. If brain size and intelligence were causally connected the blue whale would be the smartest thing on the planet and a Great Dane would be smarter than an Australian Shepherd. Also, again, you're looking at isolated chunks of data when in reality this is merely part of a much larger trend over a much, much longer time. When you look at ALL the data, as in that link I posted, you'll see that your question is simply not valid.
Here's a fun link to a site showing the brain size in various animals.
Also, I should point out that we don't actually know precisely how big the brains of any human other than
Homo sapien sapien are. We can estimate the size, based on the size of the skull cavity, but without an actual brain to measure that's all this is: an estimate. Any number of soft-part anatomical features (such as increased fluid in the skull cavity, thicker soft-tissue envelope encasing the brain, and the like) can cause our calculations to be in error. This is an obvious point, but it's one of those points that it's good to remember in paleontology: unless you're EXTREMELY lucky, all you know for certain is the hard parts.
Interesting but straying from the point.
No, that's the entire bloody point, actually. You're arguing that there are significant changes in the brain at a particular point in time. It was demonstrated, quite spectacularly, that while there are differences in
size, there's no significant differences in
form between humans and orangutans. Since your argument implies that there was a dramatic shift in brain
function, size isn't the relevant issue--form is.
nteresting. Perhaps this might be shown to apply in some way, but so far I don't see any specific examples that are related to the specific question we're dealing with. If you have any, again please post the links.
Really. You don't see how taphonomy--the study of HOW FOSSILS FORM AND ARE FOUND--might have some relevance to your point regarding the absence of transitional forms.
Here's a hint: Humans are generally found in rift valleys. These are typically erosional environments.
I've done no such thing. Again ... All I've done is ask some questions and post some observations.
Your observations are wrong and your questions are based on an artificially limited sub-set of the data.
If we already have the evidence then why are scientists trying to explain the anomaly?
Dude, have you MET any scientists? I once spent a month arguing the advantages and disadvantages of blowing up the Moon. I spent an evening with another scientist trying to figure out how to make an outcrop with the texture of pumpkin pie. We'll argue anything. Also, if you ask two paleontologists for an opinion you'll get three answers. People disagree with me. It's the nature of the beast. I could easily find scientists who question the very validity of asking "Why did brains get bigger?" in the first place (read Gould's work on architecture to see one example).
Instead we see some transparent attempt to turn the tables while appealing to unproven authority.
Actually, I am a proven authority (a minor one, but I certainly have proven that I'm a real-life paleontologist). I've published peer-reviewed papers, given a talk at an international symposium, and my official position at the company I work for is "staff paleontologist". This is what I DO; this is how I feed my family. And that's why I get so annoyed at people like you demanding that I take you seriously--you haven't done what I consider to be the most basic research on the topic (the fact that human brains have a geometric growth is something that I taught freshmen when I was in grad school), yet you feel perfectly confident to dismiss highly relevant topics as irrelevant, merely because you don't understand them and to tell me what my peers think. You keep talking about "the experts", while your only citations have been to Darwin (on a topic he got wrong--look into WHY he said what he said sometime, and something called Neocatastraphism). It gets old fast. You'll have to forgive my brusqueness, but you're not the first person to do this, or even the only one doing it right now.
I don't expect you to take what I say as gospel truth merely because I say it, particularly since anthropology isn't my strong suite (the archaeologists take away all the human bones, which I'm generally okay with). However, I DO expect you to be able to substantiate any refutations, particularly considering the fact that I've referred to numerous papers that you've thus far simply ignored (hint: PUNCTUATED EQUILIBRIUM).
A real scientist couldn't tell you
Please spare me your list of rules of how "real scientists" behave. I've never seen one that's even close to accurate. A much better way to learn what real scientists do is to interact with a few, and figure out how they act--rather than coming up with the rules first, and demanding all scientists (a group I assume you're not part of) act.
Telling scientists how to act isn't going to impress anyone, and will only annoy those who are capable of answering your questions. And scientists certainly DO dismiss arguments out-of-hand. Science has rules, and the first rule is that before any idea is taken seriously positive evidence (meaning evidence indicating it's true, rather than merely indicating that it's not necessarily false) must be presented. You find me positive evidence that aliens actually manipulated our genome and I'll take it seriously. Until then it's baseless speculation and will properly be dismissed as such. And if you think that's rough, you should see what a journal editor says when they think you've engaged in baseless speculation!
I do what I can.
