Forum:An unemotional query

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I am not a biologists, so sorry if I'm being stupid here... I was recently asked the following question that I don't know the answer to:

If evolutionary theory is correct, then why don't we see a whole (fairly continuous) spectrum of life today? Why are there all these disjunct categories of species and genera, and seemingly nothing in-between?

I have been trying to find something on the internet about this, but all I can find are very biased creationist views and highly irritated evolutionist responses.

Could someone please explain this issue to me intelligently, and, if possible, objectively? I'm interested in the truth here, not why creationists are stupid...


p.s.: I can kind of understand the bias of creationists, but, quite frankly, I am baffled by the emotions shown by the proponents of mainstream science on this issue... Why is everybody so angry all the time? --Lbejo (talk) 13:10, 4 October 2011 (UTC)

That's a fair enough question. I'm sorry people were rude to you about it, but there are jerks everywhere. Particularly when you ask such a question with terms like "genera," it makes it seem like you already have an answer and are just trying to be snide or "prove" something - most people who know the relevant jargon already have an answer in mind.
I'm not a biologist either, but I think we do see a pretty big spectrum of life. Take the spectrum of life as it can live in the water. Every possible iteration is represented: Fish in the deep sea, fish in the shallow sea, fish in the streams of fresh water, fish that can go on the land for a short period, amphibians that go in the way for long periods, amphibians that go in the water for short periods, mammals that swim occasionally, and mammals that live in the desert and never see more than drops of moisture.
Did you have some specific missing examples in mind?--ADtalkModerator 13:12, 4 October 2011 (UTC)
No, I actually do not have an answer in mind, and not just trying to prove a preconcieved point... What I'm wondering about is not so much the width, but rather the continuity of this spectra (or lack thereof). The most notable example is of course; why is there nothing in-between apes and humans? Should there not be some intermediate forms as well? Or were they there at one point, but, being inferior, could not compete with humans and gone extinct? What is the reasoning here? (I imagine my questions give my ignorance away - please excuse me...)— Unsigned, by: Lbejo / talk / contribs
There's nothing to be sorry about. Curiosity is the beginning of knowledge.
It does seem to me like yes, there once were more intermediate forms, but we beat them out. Humans are staggeringly good at competition, and we've spread throughout the world and dominated it beyond any other closely-related species (by a wide margin). We were just plain better at doing the things we do. We're smarter than our predecessors, for example, and we can run farther distances. Those species that were enough like us that they were trying to live like us, by being smart and running, couldn't do it as well. So they died off. Other species tried a different way of surviving, like the apes, and so they're still around (mostly - we've killed some of them off, too). We're just really good at being smart, so our competitors got wiped out. Even some animals we're not competing with have been wiped out because we're so successful as a species, in fact.
We have a lot of transitional fossils from those species, though, so we know they once did exist. And in fact they match up pretty well with how we'd expect, so we know that our theory about them is probably right.--ADtalkModerator 14:20, 4 October 2011 (UTC)
Though I think it can't be overstated that the idea of a continuum of living creatures would be very much susceptible to the "you've found a transition to fill a gap, now you have two gaps!" argument. The fact is, life does exist as a remarkable continuum already - it's not like we have one ape, one cat, and one horse in the wild. You can form hybrids between sufficiently related species, ligers, tigrons, those weird zebra things and then you get mules and the ability for bacteria to start swapping genes with each other like college students swap STDs. We see features in many different stages of development, in aquatic organisms especially where you look at a mudskipper and wonder if that's a fin or a leg. Life has no pressing need to be so blatantly obvious about its evolutionary origins as it is, never mind us demanding it to be more so! ADK...I'll pander your bingo! 16:11, 4 October 2011 (UTC)

I would say you're looking at how and why speciation occurs. For you to see the continuum of life you're suggesting, you would expect speciation to occur very spontaneously. As it happens, it doesn't. You need to split your population of X into two groups, X1 and X2 by some physical boundary. Environmental changes being common but there are interesting man-made ones, for instance the Great Wall of China and several wide roads effectively stop gene flow between two populations, allowing speciation to occur. So you will expect great differences to appear - otherwise they just wouldn't be separate species. But if they weren't separate species, they would interbreed and such distinctions would be ironed out somewhat. Now, if you're talking living links between apes and humans, you have to remember that humans have had really quick evolutionary advancement in terms of intelligence. While I'm sure professional evolutionary biologists will kill me for this metaphor, imagine a Formula 1 race where they're all tightly packed, and the one car suddenly gets a massive boost to its engine and races off ahead. The others might randomly get that boost too, but you'd expect a big enough gap between that boosted car and the rest of the pack. Then recall human and related ancestors that are now extinct. Neanderthals, for instance, would count in this "continuum" but have since died out - so they're not around to be counted, never neglect this kind of "silent" evidence. ADK...I'll murder your flap! 13:40, 4 October 2011 (UTC)

Thank you, guys. It was enlightening.Lbejo (talk) 14:01, 13 October 2011 (UTC)

Have you read "evolution of human" at wikipedia? It's fairly straight forward, but lists a host of intermediary fossils between our "ape" ancestor, and humans. human evo Some of the famous ones are "luci" (Australopithecus), homo habalus, homo erectus, etc. There are roughly 10-20 species that are on the "ape to human" line, and another 10-20 that are believed to be co-evolving but not our ancestors. It's a pretty easy read, and to me it was very enlightening of just what ancestors we do have. Pink mowse.pngGodotThe Peyote God awaits 14:07, 13 October 2011 (UTC)
Though those are past species that have either branched out and gone extinct or are direct ancestors. Not entirely applicable to why you don't see an existing continuum today. I suppose one way of thinking about it is to think of this "conintuum" multi-dimensionally. One dimension being variation and the other dimension being time. Then it's not a case of wondering why intermediates still aren't living. ADK...I'll explicate your bathtub! 14:10, 13 October 2011 (UTC)
Well you don't see a "continuum" in that sense, today, in any form, precisely because of the tenants of natural selection. When you are competing for resources, one of you will likely win, and another of you goes extinct. In any lineage. We have the better "thinking and language tools", we'll get to food faster, use resources better and out compete those who are evolving with / beside us. I think of it that one species virtually "replaces" his immediate ancestor (at least often), cause he is better adapted. Cold ice age starts to come in, my fur is white and yours is not, I'm going to have an advantage and basically replace you. you who had a stronger jaw, replaced the guy before you. I realize it is not this way all the time, cause we both may adapt to different habitats and not directly compete (like the Aussi Gekkos who are evolving to be cave dwellers), but frequently there is a direct competition between the new guy and his "parent" guy. Pink mowse.pngGodotThe Peyote God awaits 14:15, 13 October 2011 (UTC)
Looking at it another way the continuum does exist, but it exists across time rather than (current) space. In one of his books (I think it was The Ancestor's Tale) Richard Dawkins points out that in one way we are fortunate the the fossil record record is relatively scarce. If it were totally complete then deciding where one species ends and another begins would a devilishly difficult if not impossible task.--Bob"What can be asserted without evidence can also be dismissed without evidence." 10:54, 15 May 2012 (UTC)
An interesting way of looking at it. Reminds me of this text. Scarlet A.pngd hominem 10:58, 15 May 2012 (UTC)
Oooh, check out page 11 of that thread for a font analogy that fails miserably. Scarlet A.pngnarchist 11:01, 15 May 2012 (UTC)

Debunk these, anyone?[edit]

A friend posted a link to this blogpost that argues for a young Earth... I don't know too much about these things - can someone check the validity of these arguments? Lbejo (talk) 10:31, 15 May 2012 (UTC)

Try this why not? --MtDPrematurely Indeterminate 09:37, 15 May 2012 (UTC)

That blog doesn't cite any sources and appears to be using really common arguments, so...yeah. (Also, "inventing agriculture and writing is easy!" isn't even an argument.) ~ Kupochama[1][2] 09:41, 15 May 2012 (UTC)
"Ultimately, the reason we believe the world is ~6,000 years old is because we take Biblical chronology seriously." is an interesting point, because you easily counter it where ask what would happen if you don't consider it seriously. Does Biblical chronology then derive from a system where it doesn't exist? That's how reality-based science works; you stop believing in it, and you see if it goes away. Scarlet A.pngtheist 10:36, 15 May 2012 (UTC)
Those are all in another article we have:
Preserved DNA and Soft Tissue in Fossils
Radiocarbon Dating Inconsistent with Old Earth
No living organisms older than a few millennia
No civilization older than a few millennia
HTH. CrundyTalk nerdy to me 12:58, 15 May 2012 (UTC)