God I hope this is not a stupid question. Please don’t laugh.
Out birding today after spotting a little Nashville Warbler I wondered the following: How long has this species existed in the form that we see now? In other words, when did it become the creature we see now.
Did it look mostly like it does now during the middle ages?
Please don’t mock me!
I do understand evolution. At a certain point though all living things we see today had to have reached a point where they more or less look like they do now.
IIRC, modern birds seemed to have evolved during the Cretaceous period, ending about 65 million years ago. But I have no idea when that particular bird, or similar ones, emerged in something like their modern form. Fossils from small birds can be hard to find. I don’t what kind of evidence we can base a guess on.
Given the usual speed of speciation, though, I think we can be fairly sure of saying “yes, it looked roughly the same during the Middle Ages.” Species that change a lot in a mere few hundred years are relatively rare.
I would add, though, that it wasn’t called the Nashville Warbler during the Cretaceous period.
Cite?
Even the city wasn’t named Nashville when founded in 1779, which I believe was shortly after the end of the Cretaceous period.
It’s not a silly question. Some species have been the same for hundreds of millions of years (e.g. cockroach, bullhead shark, ginkgo tree) and others have been around for only a few million years (e.g. humans). Some species of bacteria have probably been around for only a few tens of thousands of years.
But as TimeWinder points out, it’s unlikely that a complex vertebrate species like the one you mention was too terribly different 600 years ago. Perhaps our resident ornithologist can give you greater specifics on this particular species?
Like my wife said, ‘when did a robin look like a robin?’
Here’s what David Sibley says: that the prototypical wood warbler evolved in Central America by the late Miocene, so nine million years ago. Then: “the diversity of the wood-warbler genus Dendroica is presumed to have arisen from repeated subdivision and differentiation of populations as glaciers advanced and retreated across North America over the last few millennia.” So the Nashville warbler is something of a newbie, apparently.
Actually, I just thought to look it up, and find out that the Nashville warbler is not after all in the genus Dendroica. But close!
The point to realise is that species come into being via a series of infinitesimally small changes. There is never a specific point at which you can say that a creature came into being.
To give you some idea of how slowly bird species change, have a look at this bird. Then look at this bird.. See the difference? No, well neither does anybody who isn’t a fairly keen birdo. FTR, the second bird is your Nashville Warbler. The first bird is a closely related species.
Those two birds have been considered good species, so we can assume they have been isolated for a long time, though how long isn’t clear. Based on their current range, we could assume they were a single population at the end of the last glaciation event, ~10, 000 years ago. That tiny degree of change is fairly typical of the type of variation you can expect in birds in anything less than about a million years.
That essentially answers your question. It usually takes millions of years to produce really distinctive species. The middle ages were only a few hundred years ago, the birds would have been identical to what you see today. At the time of the last Ice Age your Nashville Warbler would have presumably looked
somewhat like a hybrid between the two birds in the photographs, which is hardly a distinctive difference from how it looks today.
As for when your warbler came into being, there’s no definitive answer. If you take a look at this bird, you might think it look similar, but it’s actually a distinct genus, and has presumably been separated from your warbler for at least 2 million years. So if you went back to the time when the very first humans existed, your warbler would like somewhere between that bird and your warbler.. Not really a huge difference and you could certainly be forgiven for assuming that it was the same bird.
If you went back ~10 million years you might expect your bird to look like this, which is a member of the same family.
You would really have to go back 20 million years or so to get to the stage where the bird is really distinctively difference. At that stage you start getting to the common ancestor of the warblers, cardinals and sparrows. If you can imagine a hybrid between a cardinal and a warbler, it’s going to be significantly different from your bird.
So from a layman’s POV, you have to go back somewhere between 10 and 30 million years before you start getting birds that are *obviously *not the same animal.
Thanks, Blake! Thanks to all of you.
Ahh, no.
First off none of those creatures are species. Cockroaches and Ginkgos are entire orders, bullhead sharks are a family.
Secondly none of those groups have remained unchanged for hundreds of millions of years, In the last few hundred million years cockroaches have evolved into armoured, flightless subterranean forms the size of your hand, tiny termites the size of a grain of sand and highly aerobatic nectar feeders. Nobody in their right mind would mistake those animals for the same species. Ditto for the ginkgos and the sharks.
Certainly some *gross forms *within those groups have remained fairly conservative, but that isn’t evidence of a lack of speciation or even evidence that the form is conservative behaviourally or biochemically or in subtle form such as ornamentation.
I know it’s common for junk sources like the History Channel to say that cockroaches or crocodiles have been around for hundreds of millions of years, but it simply isn’t true. Or at least, it’s no more true than saying that humans have been around for hundreds of millions of years. Species within the crocodile clade have existed for hundreds of millions of years, but species within the human clade have existed for just as long. No individual species within any clade has existed for that long.
I won’t bicker with you about whether they count as “species” for the purposes the OP has in mind. Remember – the OP asked if this bird still “looked like” what it did in the middle ages, and bashfully hoped it wasn’t a stupid question. I’m just pointing out that it’s not.
So either 1) you’re being a wee mite overly pedantic, or 2) you should, in the interest of eradicating ignorance, go delete the wikipedia entry for living fossil, from which I got all of my examples.
So you got all your information, which I have shown you is factually incorrect, from a Wikipedia article that is clearly flagged as being in desperate need of expert attention.
That probably isn’t a good way to go about eradicating your ignorance of the topic.
Just to add to the irony, the article itself states quite clearly exactly what I said: such orgnaisms are are neve the same species and that “Note that just because a living fossil is a surviving representative of an archaic lineage does not necessarily require that it retains all of the “primitive” features (plesiomorphies) of the lineage it is descended from”.
There is simply no justification for your claim that some species of cockroaches or ginkgos have been around for hundreds of millions of years. That claim is utterly untrue and is even contradicted by your own reference. This isn’t a point that you can “bicker” about. The statement is incontrovertibly incorrect in every sense.
It is a good question and the answer is that, past the point of recorded natural history we don’t really know.
Sure, evolution happens but we have still to be sure whether it follows the gradual or the “punctuated equilibrium” model. (or both).
In the former you might have to go back hundreds of thousands of years to see a substantial difference in body form. For the latter, who knows? perhaps only thousands of years.
My own opinion? both are plausible and possible and likely to have occurred in certain places for certain species. I base this on no evidence whatsoever, merely the acceptance that there is rarely a single, neat answer within the natural world. Weird stuff happens
(which I believe was the original title of Darwin’s most famous work, followed by “Damn nature…you scary!” before settling on the more prosaic
Just to elaborate on this, even such famous “living fossils” as the coelocanth are no such thing. The modern coelocanth is an entirely new genus unknown in the fossil record (and, again, “coelocanth” is an order, not a species). It’s not being pedantic with respect to the OP’s question either: it’s analogous to answering the OP with “yes, the species ‘bird’ has remained relatively unchanged since it evolved in the Cretaceous.” Long story short, the concept of a “living fossil” is total baloney and needs to die a quick death. /rant 
With respect to the OP, various species of birds can emerge relatively quickly due to subtle evolutionary forces like shifting breeding seasons, so it’s quite possible that this particular species looked different, and maybe would even have been considered a different species, during the middle ages. But without some work on molecular clocks and divergence times it would be impossible to know.
Interestingly, a new species of sparrow has recently emerged in Italy: http://www.bbc.co.uk/nature/14947902 (not recently discovered, but recently speciated, for certain definitions of “species”).
Under human selection, a species can change its appearance dramatically over a few hundred years. All dogs are the same species, but different breeds look very different. Read Darwin on pigeon varieties too. But this is just superficial appearance.
