I am a firm supporter of the "Theory" of Evolution myself, and natural selection makes perfect sense to me, but what are we to say to those who want to see intermediate species? Is it that the surviving version of an evolved species is so much better and what it does that the earlier version doesn't stand a chance? And if that is so, has it been true across the board for all species? So my question simply is: are there no intermediate species at all that can be pointed out to those who insists on them in order to accept Darwin's ideas?
Are there any Intermediate Species to point at?
- Thread starter Epictetus
- Start date
@Epictetus --
That depends on how technical you want to get because technically all extant species are intermediate species. For most purposes though there are enough clear examples of "intermediate" species in the fossil record to satisfy anyone with a brain. Pointing to clear examples of extant "intermediate" species is going to be impossible because we don't know what they're evolving into, it hasn't happened yet.
Of course what most people are really asking for when they're talking about intermediate species is that they want evidence of speciation, which can easily be demonstrated by the existence of ring species.
In some cases perhaps the two were competing directly, however that's not usually the case. The most common cause of speciation is geographical separation of different populations of the same species. Because the two populations can no longer interbreed genetic differences build up in the different populations eventually leading to the point where they would no longer be able to interbreed even if they came into contact with each other.
That depends on how technical you want to get because technically all extant species are intermediate species. For most purposes though there are enough clear examples of "intermediate" species in the fossil record to satisfy anyone with a brain. Pointing to clear examples of extant "intermediate" species is going to be impossible because we don't know what they're evolving into, it hasn't happened yet.
Of course what most people are really asking for when they're talking about intermediate species is that they want evidence of speciation, which can easily be demonstrated by the existence of ring species.
In some cases perhaps the two were competing directly, however that's not usually the case. The most common cause of speciation is geographical separation of different populations of the same species. Because the two populations can no longer interbreed genetic differences build up in the different populations eventually leading to the point where they would no longer be able to interbreed even if they came into contact with each other.
I doubt the people I have in mind want to get technical at all. You say we don't know what something is evolving into, but what I think is needed, as ridiculous as it sounds, is something that is clearly at some mid-way point between two known species: a half alligator-half man, if you will. I know such a dramatic chimera doesn't exist, but perhaps among insects or bacteria...?
DaveC426913
Valued Senior Member
You say "your premise is flawed".
The concept of an intermediate species arises from the mistaken belief that animals we see today are perfectly evolved for their environment - any more than any another recent or ancient species - and need not evolve any more. The whole point of evolution is that species are always in flux as a result of environmental demands, competitive pressures and energy budgets. All living and dead animals are intermediate in the sense that they have pressures on them to survive and breed.
A half alligator half man would, if validated and duplicated, throw a big wrench into a lot we understand as true in evolution and biology. It's a classic case of falsification, and something we don't see. Major changes don't happen between parent and offspring, they take numerous generations and populations to gradually transition from one form to another.
Here's a half-squirrel half-bat:
http://animaldiversity.ummz.umich.e...s/Anomaluridae/Idiurus_macrotis.jpg/view.html
Note the evolving wing. So far only one bone, but it's getting there.
I am not sure if this counts but it has to do with the flower called four oçlocks which open in the late afteroon. From wikipedia:
Epictetus
There is no such thing because man did not evolve from aligators, though at one time they did share a common ancestor but it would share only general skeletal arraingement similarities. Every creature with two arms and two legs has that much in common, from amphibians on up.
But I can point to a creature that even creationists have a problem with...
http://www.gwu.edu/~bygeorge/march19ByG!/evolution.html
Grumpy
There is no such thing because man did not evolve from aligators, though at one time they did share a common ancestor but it would share only general skeletal arraingement similarities. Every creature with two arms and two legs has that much in common, from amphibians on up.
But I can point to a creature that even creationists have a problem with...
http://www.gwu.edu/~bygeorge/march19ByG!/evolution.html
Grumpy
DaveC426913
Valued Senior Member
No. This too is based on flawed assumptions.
The squirrel has attributes that evolved based on what needs its ancestors had. There is absolutely no such thing as prediction or direction in evolution - there is no reason to think evolution is working toward a flying squirrel with bones in its flaps.
And it's not at all batlike. Bats have their wings between their fingers. Squirrels using flaps of skin on their sides. This is convergent evolution - two unrelated ways of solving the same survival problem.
There is no transition between and alligator and a man, all modern species share ancestors, so you can find, if you are lucky, the population that gave rise to the alligator [and others] and humans, but that population wouldnt be half-man, half alligator.
Take Spidergoat's pic of Lucy and tell your friend to wave and say "Hi Mom!" :wave:
Check out Lucy's feet. She has gotten rid of her granny's prehensile toe (A. ramidus aka Ardi). Lucy was a mind-blower, but Ardi blows the "missing link" question out of the water:
http://news.nationalgeographic.com/news/2009/10/091001-oldest-human-skeleton-ardi-missing-link-chimps-ardipithecus-ramidus.html
In short, Ardi renders the question moot.
As for intermediate species between mammals and reptiles, the denier should read up on
http://en.wikipedia.org/wiki/Synapsid
As for discussion of surviving ancestors
http://en.wikipedia.org/wiki/Crown_group
And in general
http://en.wikipedia.org/wiki/Evolution_of_mammals
Here is a list of transitional fossils
http://en.wikipedia.org/wiki/List_of_transitional_fossils#Synapsid_.28.22mammal-like_reptiles.22.29_to_mammals
Correct. This clearly included some level of flight. Hence the evolution of both the wing membranes and the new bone.
Evolution DID work towards a flying squirrel with bones in its flaps. I posted a picture of such an animal. This level of adaptation may be sufficient for the animal. It may not be, in which case the length of the bone may increase and more musculature may be added to make it a better flyer. It may DECREASE - if it stops being important for the squirrel to fly (deforestation or whatever) you'd expect to see it slowly lose that flight membrane.
Both are mammals. Both use skin based membranes that are stretched tight during flight, as opposed to birds that use rigid feathers to maintain a flight surface. They clearly have some similarities.
Two quite related ways of solving the same problem - but less related to the most common solution, feathers.
This squirrel will not, of course, turn into a bat as we know them. If it continues its evolution and expands its ability to fly it will look like something quite different, although it will maintain many of the similarities the two species already have. But it is somewhat remarkable in that we are seeing the first evidence of a new structure that allows it to glide a bit better than its relatives - an addition to its skeleton.
In ten million years a future version of creationist may well say "see that flying thing up there? What, did it just grow wings one day and fly away?" They will say that because they did not see this stage - a regular old flying squirrel with just one adaptation that sets it apart.
But evolution doesn't have a goal in place, other than survival to the next generation. You're correct about the rest, as things change the direction of wing like development might take different paths, but there is no set goal to work towards as far as characteristics. If the organism reproduces, the genes get passed on. If not, they don't. If those wings contribute to the passing of genes enough times, the odds are in favor of us seeing more of that characteristic.
And, you might not see membranes regress if they become less important, if they don't contribute negatively to survival. In a treeless environment we could see them with these flaps that are useless, and speculate why on earth did they develop where they can't be used to fly. Maybe they become useful in some other purpose, such as protecting the young or holding nuts or something.
The only few real instances would be "ring species" and things like the finch species of the genus Geospiza (there are three ones, two "extremes" and one "intermediate" in between, they sometimes interbreed).
But before even going there, it's important to have in mind that it's very likely that most people asking for such evidence are falling in contradiction with themselves as they're very likely to accept that there's speciation, at even faster rates than science assumes to be the norm -- that's in order to have a literal reading of the Noah's ark episode, at the same time one knows that there are more terrestrial animal species than those found at any given zoo.
The next logical step would be to fist ask them where exactly they draw the line of "unrelatedness" between two closely-related taxa, at which level. And why so. The odds are that they won't be able to do neither. Draw the line, nor give some seemingly coherent "explanation" to why they think that the apparent relatedness there is "fake" while the same evidence supports real relatedness within that line.
If we were to merely obbey "debate" rules the game would be over here, as the burden of proof is all theirs now -- as biological reproduction/evolution/biogenesis is a more parsimonious explanation for any such case than spontaneous generation/special creation, and that's something interesting to point out, I guess.
But we're usually doing more than our fair share of the deal, so, if that's not really enough, you can just take any two closely related taxa and show that they differ more or less like the taxa of the lower level differ, that is, genera within a family differ more or less like species within a genus. In other words, it's somewhat as if all species were "transitional", but really meaning that they're obviously related.
As others have mentioned, it's perhaps also a good point to make that species that are not literally "transitional"/intermediate are not an "end product" anyway, albeit that may be more or less unconsciously implied in the acceptance of genera or family as "kinds".
Two examples that I like somewhat are to take a bunch of pictures of skulls of many dog breeds, and putting somewhere in the middle the pictures of a bear skull and a fox skull. I'm limited to 3 images/message, so here's a link to a post in a different forum where I did just that.
I think that arachnids also look interestingly like a "evolutionary sequence", regardless of the sequence you suppose to be the actual one:
1. Scorpiones, 2. Amblypygi,
3. Schizomida, 4. Uropygi, 5. Ricinulei,
6. Palpigradi, 7. Pseudoscorpiones, 8. Opiliones,
9. Solifugae, 10. Acari, 11. Araneae
Moving the focus from "intermediate species"/"between species" to merely evidence of relatedness, the things get really interesting with details such as giraffes and manatees having the same number of cervical vertebrae, regardless of their discrepant neck sizes:
Not that they're particularly related, only that, mammals, differently from reptiles, seem to be quite more rigid in this regard. Such biological constraints are very hard to reconcile with any notion besides descent with modification. It's not like there's any clear functional reason why the dugong need all such cervical vertebra, or why giraffes couldn't have more (as long-necked dinosaurs and other reptiles did).
[rant]
As the years go by, more and more I think that showing all this sort of evidence is futile, most of the time. I have the impression that 99% of those who haven't an a priori commitment with the notion of organisms being spontaneously generated by miracle (or put here by extraterrestrials), would be pretty much satisfied with just generalizing evolution from the divergence observed within dog breeds, seeing how any given taxonomy looks just like an extension of that. Not that it's all that there's to know, but it's the sort of basic level of understanding that suffices for most subjects. Like we accept that the basic laws of motion govern the orbits of our planets, but rarely there are people interested/"skeptical" with things like the Apollo anomaly and questions regarding graviational interactions between more than two objects.
The difference is that the opposition/"skepticism" towards evolution has a religious basis. I think that perhaps more could be done for the acceptance of evolution (or whatever else in science that may conflict with religion) by the promotion of religious views that don't require fundamentalism (or specifically, that the organisms sprouted as they are from the mud), than by the sheer exposition of evidence.
[/rant]
Other thing we have to keep in mind is that sometimes creationists and the like seem to not have much of a grasp even of the most basic fundamentals of evolution, hence expecting something literally like that ("alligator-man"), even though it's not predicted by any phylogenetic tree.
I think they sometimes may not have even a vague notion of a universal phylogenetic tree, so they can be thinking in terms of "an intermediate between insects and vertebrates or molluscs". To give a real quote from a creationist author*:
A. E. Wilders-Smith said:
But these, along with other "chimaeric" intermediates, are not predicted by evolution and it's tree-like pattern of trait distribution. It's rather more expected from any mechanism other than the constraints of biological reproduction diverging in a tree-like pattern.
* Even though I suspect that actual creationists should know better and more than having any genuine innocent misunderstanding, are often consciously forging the misunderstanding to their readers.