Thursday, December 25, 2008
Thursday, December 18, 2008
I wish that the bald eagle had not been chosen as the representative of our country, he is a bird of bad moral character, he does not get his living honestly, you may have seen him perched on somedead tree, where, too lazy to fish for himself, he watches the labor of the fishing-hawk [osprey], and when that diligent bird has at length taken a fish, and is bearing it to its nest for the support of his mate and young ones, the bald eagle pursues him and takes it from him.... Besides he is a rank coward; the little kingbird, not bigger than a sparrow attacks him boldly and drives him out of the district. He is therefore by no means a proper emblem for the brave and honest. . . of America.. . . For a truth, the turkey is in comparison a much more respectable bird, and withal a true originalnative of America . . . a bird of courage, and would not hesitate to attack a grenadier of the British guards, who should presume to invade his farmyard with a red coat on.
Back to Bald Eagles? Ok, sure. The Bald Eagles are top predators, and primarily fish eaters (as the whole Sea Eagles thing implies). They tend to stick to major river corridors in continental interiors and congregate along coastlines. Alaska has the largest population of existing Bald Eagles, despite a concerted effort by salmon harvestors to kill them off in the early 1900s. In general, the eagle was the subject of human harassment and competition, and dramatically declined from pre-Columbian levels as the United States became more populus through the 1800s and into the early 1900s. Protection for the Bald Eagle was first enacted long before Federal Threatened and Endangered Species laws, by the Migratory Bird Treaty and the Bald Eagle Act.
Thursday, December 11, 2008
Reptiles are air-breathing, four-legged, cold-blooded amniotes that live everywhere but the polar regions. Everyone knows what a reptile is, but oddly enough, the taxonomy is a little more confusing that we might otherwise think. To understand why, I'm going to introduce two terms: Monophyletic and paraphyletic. Basically a group is considered monophyletic if it includes all the animals desended from a common ancestor. If you take a monophyletic group, and remove one of the decendents of that common ancestor, then you get a paraphyletic group.
Full of confusion? Ok, let's put it another way. Below are all the vertebrates. If we highlight a group that includes reptiles and birds, we've got a monophyletic group (sometimes called a clade).
This figure shows our best understanding of evolutionary connections. The earliest common ancestor was some kind of vertebrate, which split into tetrapods and pisces (fish). You can see tetrapods split into amphibians and amniotes.
On the other hand, the group 'reptiles' as we commonly understand it, isn't a monophyletic group. Take a look:
The term reptiles doesn't include all descendents from a common ancestor because the are believed to be part of that lineage as well. The reason this is a little weird has to do with the way humans percieve these groups of animals. Birds and mammals are 'good' animals. Reptiles and amphibians are "slimy", creepy or scary. Yet these are very different types of animals. As you can see in the figures above, they aren't even that closely related.
This perception problem is pervasive in the sciences as well. Take herpetologists. Herpetologists study reptiles and amphibians. The only real commonalities are that they are cold-blooded and generally smallish. Is this really a meaningful basis on which to lump these otherwise very different groups together? (...no)
Ok, but let's get back to reptiles. I've repeatedly used the term amniote without really explaining it. Maybe I should fix that? Amniotes are animals who's embryo is surrounded by protective membranes: They lay eggs that could survive on dry land! This improvement on eggs was the big development that separated the earliest reptiles and proto-mammals from the amphibians. At the time, amphibians were the masters of the terretrial terrain. However, amniotes were able to exploit a lot more land, and eventually began to displace amphibians as large, dominant herbivores and predators.
Reptiles, or at least, creatures that we would look at and think "reptile" predate mammals, and therefore you can safely consider mammals and birds specialized reptiles, if you feel like it. Those of you who think I'm crazy: Its right there in the family tree!
What did an early proto-reptile look like? Well, according to Wikipedia, Hylonomus is a good guess for one of the first reptiles:
Yeah, that was predictable huh? There are only 4 classes of reptiles left today (if you don't count mammals or birds). The crocodiles and the turtles are two of those classes. The third one is everything else you think of as a reptile: Snakes, lizards, mosasaurs (these are squamates). Unless you're amazing or a herpetologist, you probably have never even heard of the 4th group of reptiles. Why? Because (this is going to be a huge shock) even if you saw it, you'd just think it was a lizard.
I'm talking of course about the order Sphenodontia, a once hugely diverse order that now contains just a single species: Tuatara. And if you know anything at all about how the world works, you know this single remaining species of a once-great order is on the verge of extinction thanks to something mankind did. Fantastic. In this case, we brought rats to New Zealand.
Tuatara is a pretty ridiculously interesting animal. Like the last surviving member of any ancient lineage, people tend to refer to this species as a 'living fossil'. However, this has always been a hopelessly stupid thing to say. The implication is that the animal hasn't changed in the thousands or millions or tens of millions of years since our first fossil record. The likelihood of this being the case is incredibly small. Animals evolve to survive changing conditions, and there is basically no-where in the world that hasn't had changing conditions over the last 220 million years. Hence, this species had to have evolved. In fact, these guys (whose work I can't get anywhere) apparently found that tuatara is changing more rapidly than any other species tested.
Ok, aside from that tuatara has a third eye, incredibly primitive ears, and a fish-like spine (all unique or rare among reptiles). And now let's go back to reptiles.
There's a lot about reptiles is amazing, but I'm just going to talk about one more thing and leave it at that. Basically: How do they breath?
This seems like an obvious question. After all, we all instinctively know how mammals breath, and if you dig around the medical literature, you'll find talk about a diaphram and muscles causing your lungs to expand and contract.
Of course, this is how reptiles do it too, but in the case of the squamates, those muscles are also locomotion muscles. So when a lizard starts running, it isn't breathing. I haven't found anyone who says this, but I imagine this is why you see lizards making short bursts from hiding place to hiding place. The crocodilians breath differently. Like mammals, crocs have a diaphram (although it works a little differently). Turtles are where it gets really interesting. I don't know how many of you have seen a turtle, but they have a hard shell. Exactly how do you get your lungs to inflate and deflate if they are attached to a hard shell?
Turns out, different turtles do it differently. For the most part, there are two sets of muscles: One that pushes everything inside the shell out, and another set that pulls everything outside the shell in. Expand-contract. You get the idea. These muscles might interfere with locomotion, or they might not, depending on the species. You may also think: Aren't there a lot of aquatic turtles? Why yes, yes there are. And since you asked, some of them appear to breath from the butt.
Don't worry though. They aren't drinking from that oriface.
Well, that turned into a sufficiently bizarre post. Hope everyone enjoyed!
As Rattlerjen points out, yes, its really the cloaca that turtles are able to respire from (butt is a non-technical term in this case :), although this is limited to side-neck turtles. However, I can't find any actual evidence to back up Rattlerjen's other claims. The paper I linked to previously (the link doesn't seem to be working, so the citation is below) actually demonstrates that cloacal drinking does not occur in a species that is able to breath that way. Anyone have any citations to share on other species?
Charles C. Peterson and David Greenshields. 2001. Negative test for cloacal drinking in a semi-aquatic turtle (Trachemys scripta), with comments on the functions of cloacal bursae. Comparative Physiology and Biochemistry DOI:10.1002/jez.1055
Thursday, December 4, 2008
Eitzmann, J.L. and C. Paukert. 2007. Annual performance report: Distribution and Abundance of fishes in the
McPhail, J.D. and C.D. Lindsey. 1970. Freshwater Fishes of
Patton, T.M., F.J. Rahel, and W.A. Hubert. 1998. Using historical data to assess changes in
Rahel, F.J. and L. A. Thel. 2004. Flathead Chub (Platygobio grcilis): A technical Conservation Assessment. Rocky Mountain Region,
Thursday, November 27, 2008
Where I grew up, and across much of the 'westernized' world, Wisdom teeth are removed during early adolescence or early adulthood as a purely preventative measure. Wisdom teeth that come in wrong in some way can lead to the crowding of other teeth, infection, impaction, and other problems. However, more recently, several studies have been attempting to determine whether preventative removal of wisdom teeth is appropriate. This summary in the Cochrane Library suggests that there is no reason to remove wisdom teeth until they are causing problems, although the data is apparently very limited.
In my case, the early prognosis from my dentists when I was in high school and college was that my wisdom teeth would come in with no problems. Considering both my parents had wisdom teeth problems, my sister did, and all my relatives on my mom's side did, I should have expected that these teeth would need to be removed eventually. Six years ago I had a wisdom tooth come in Mesioangular impacted, which means it came in facing the front of my mouth (see images on the Wikipedia article for reference). This is apparently the most common orientation of impacted wisdom teeth, and has the potential to crowd or damage the other molars. In my case, since I basically did nothing for 6 years, so I probably have some damage on my 2nd molar. Here's to hoping that's minimal.
I've been unable to find good data on what proportion of individuals have wisdom teeth that are impacted or the proportion that just have them removed (impacted or not). Some recent studies have suggested that even if they aren't causing obvious problems, they may be detrimental. WebMD suggests not removing them at all if you are over 30 and haven't had any problems. Partly this is because not all wisdom teeth pose problems, and partly it is because the older you are, the more the bones around your wisdom teeth have hardened and the longer and more painful the recovery is. Past a certain age, I imagine wisdom teeth are simply not removed.
A huge amount of variation exists among different human populations in the occurance of wisdom teeth (and in the number and arrangement of teeth in general). Citations in this PNAS study (which is really talking about the genetic controls over tooth formation) indicate a range from 0.2 % occurrence for Bantu speakers of Angola to virtually 100% in Mexican Indians.
The whole idea of wisdom teeth is a strong bit of evidence for the continued adaptation of humans to their environment. The exact mechanism for the changes in human jawbones is not clear, but it definitely seems to be related to diet (short discussions here and here). As humans began eating less coarse foods, the jaws began getting smaller, and the teeth (controlled by a different gene) did not have enough room to all fit in the jaw without problems.
I've actually known a number of people who've had their wisdom teeth function perfectly normally. When I was getting a blood test last week in preparation for my wisdom teeth removal, the lady who was taking my blood said that she lost her 2nd molar, and the 3rd molar (wisdom tooth) filled the opening this created and she got good use out of it for 20 years (eventually she had to have it removed...maybe she doesn't brush?). I've heard a few people whose wisdom teeth came in just fine, no problems at all. I'm not really sure how frequently any of these things happen, and I don't have access to very good medical journals.
I was fairly terrified about the prospect of getting my wisdom teeth removed. I've never been under general anesthetic before, and both my sister and dad have had some problems coming out of general anesthetic in surgeries they've had. Plus, there are a number of painful and annoying impacts of the surgery: Swelling, bleeding, and possible nerve or sinus damage. Problems which are more likely the older you are, and I've been feeling very old lately (I just turned 30).
I'm writing this on Tuesday, and I had the surgery on Monday, and I can tell you that my fears were vastly overblown. The surgery itself was brief, painless, and even though I was partially aware during the procedure (turns out it is not a true general anesthetic), I felt no pain or nervousness once sedated. Yesterday I felt great when I got home, and have have very little lingering pain. Today, especially this afternoon and evening, have been a lot more painful, but I think part of that has had to do with me wanting to avoid the pain meds as much as possible. I've also not eaten much, simply because I'm already sick of ice cream, yogurt, smoothies, etc.
Overall, if you're considering this surgery at the advice of a dentist or doctor, I recommend you do it immediately. I've had several painful experiences in my life (ulcer, concussion, foot surgery) and this is no-where near that level of pain and discomfort. Its more like 'persistent headache' than 'injured'. I think that if you need it done, its probably better to get it over with as soon as practical instead of waiting (yes, I'm talking to you!).
Some other references and guides to the whole wisdom tooth removal process:
Thursday, November 20, 2008
I know of 5 restaurants in Kansas, 1 in Texas, 1 in Oklahoma, 2 in Indiana, and 1 in Missouri that all have the same, exact, menu. The combinations are all the same, the lunch specials are all the same ("The Speedy Gonzales"), the appetizers are all the same.
Why are all these menus the same? (and yes, I realize this is a different topic for the blog but this is analyze EVERYTHING, not just "Analyze Animals")
My co-worker Eric Johnson and I came up with several hypotheses in our 9+ hours driving the last two days:
1. The restaurants are all owned or financed by the same firm.
2. Random chance (we'll call this the null hypothesis).
3. The food supply firms are selling/promoting this menu.
4. This is the menu all restaurants have in mexico. (which just pushes the question into mexico)
5. There was some 'immigrant worker' promotion years ago which started this and it has just been passed down.
I'm skeptical that this many restaurants all decided to label that particular combination of food items the "Veggie D". Mexican restaurants that don't have this menu (I know of several) generally don't have any Veggie menu at all.
Possibility 4 is one I can't get at, because I haven't spent any real time in Mexico. Anyone got any clues?
I am skeptical that a single entity finances all these restaurants across the country. Maybe something like this is happening, but how would these random guys who start the small town restaurants all over find the investors?
So I really think it comes down to 3 and 5.
The food service industry is the possibility I deem most likely. This thread on Chowhound seems to suggest this possibility, without having any direct evidence. There are only a handful of large-scale food suppliers in the country though: Dot Foods, Sysco, Keith, Hawkeye. I've been unable to find anything online that looks like this kind of menu being sold, but I'm sure they don't have everything online.
Quick Aside Here: The industry group that represents food suppliers (the International Foodservice Distributors Association) has an article on their website that is accompanied by pictures which, for reasons I can't even articulate, I find incredibly humorous ("Look at how serious I am"). Some of the quotes are equally priceless: "We are now insisting that they begin to bring their logistics people to our top to tops that we have with them throughout the year." That quote is repeated twice, so I doubt it is a typo, but seriously, does that mean something?
At any rate, I'm totally stumped. I asked reddit and got back a bunch of irrelevant gibberish. Anyone got any clues?
Thursday, November 13, 2008
What? You've never heard of a Mosasaur? Imagine a crocodile with flippers and you're superficially there. See, way back around 100 million years ago the North American continent was split by a vast epeiric sea (a shallow, salty, inland sea) called the Western Interior Seaway (really creative science people).
The whole physics and biology of the Western Interior Seaway and other epeiric seas is pretty amazing, and we'll get into that later. For now, let's just focus on what is known: The sea was shallow (for a sea), probably extremely productive, and was fed by mini-continents on either side. In limnology we tend to think of shallow waters as being the most productive, because of the ability of rooted plants to grow. I think the same is true of shallow seas, but I don't think it is for the same reasons (any oceanographers care to enlighten me on this?).
Anyway! The top predator of this inland sea and the ocean at large became the mosasaur (pictured below). Although this is a reptile, this isn't a dinosaur, and it isn't a crocodile. Think lizard. In fact, think monitor lizard (Family Varanidae), which includes the still living and awesome Komodo dragons and the recently extinct Megalania (the feared giant lizard of Australia). Many modern monitor lizards are highly adapted for living in and around water (e.g., water monitors), and so it isn't hard to imagine a scenario wherein these amphibious lizards took the next evolutionary step and became aquatic.
And become aquatic they did! Unlike turtles, crocodiles, walruses, and quite like whales and dolphins, the Mosasaurs gave birth at sea, to live offspring. The arms and hands of this species developed into flippers and became somewhat detached from the backbone (meaning they could not support their own weight on land). Pull this lizard out of the water and it would asphixiate.
One of the many interesting things about this invasion of the seas by lizards is that they weren't exactly getting themselves into an unoccupied niche. The first real mosasaurs occurred in the Cretaceous, and by 90 million years ago (MYA), we had three big subfamilies with lots of known species. However, way back in the Jurassic reptiles had already colonized the oceans with the famous plesiosaurs (think the mythical Loch Ness Monster) and of course the everpresent sharks had managed to come up with a particularly devastating breed (the Ginsu sharks) and you had other random nastiness lurking out there (just don't go swimming in the Cretaceous). Nevertheless, the Mosasaurs got really big and are generally thought to have been the top predator.
The reason I started getting interested again in Mosasaurs was an interesting paper by Mike Everhart published in the latest issue of the Kansas Academy of Science. The paper explores the occurence of mosasaur on mosasaur violence. And for something that happened 90 MYA, we can actually figure out quite a bit. Everhart was able to, fairly convincingly, estimate the size and mass of the attacker and the way in which it bit down on the victim.
The way Mosasaurs ate is interesting, and has lead to some debate about the origin of snakes. Mosasaurs, unlike sharks or dolphins or most other big predators we're familar with, didn't have teeth that cut, just teeth that crushed. As a result, Mosasaurs either had to bite their prey in half (although this might have been possible, the family lacks the heavy skull that is common in crocodilians, making this somewhat unlikely) or swallow it whole. In order to maximize the food consumption, the Mosasaurs apparently had a somewhat hinged jaw that has lead many people to think: SNAKES!
Indeed, the theory of a shared snake and mosasaur marine ancestory has recently been in vogue, although it was first proposed in the 1890s (it's called Pythonomorpha if you're curious). The idea of snakes evolving from water lizards sounds inherently unlikely to me (why evolve flippers if you are just as good off just getting rid of limbs altogether?). Luckily, I don't need to push my uninformed logic, because apparently more recent fossils have shoved this theory to the wayside (read the link on the Phythonomorpha to get a better understanding). You can rest comfortably, however, knowing that this issue will continue to be fought bitterly by individuals committed to one side or the other until they die, at which point the next generation of paleontologists will find some other issue to argue about. And you thought politics lasted forever.
Mosasaurs have been found with a variety of food items in their stomaches: Mostly fish, but also a plesiosaur, other mosasaurs, turtles, birds, and sharks. I know sharks are fish too, but at least some species of sharks appear to have gone extinct as the mosasaurs became more prominent, suggesting they might have out-competed them (via direct predation?). Some species appeared to specialize on clams, and at least one late evolving species (Leiodon) managed to evolve teeth that cut. All of this evolutionary achievement probably put the Mosasaurs at the top of the oceanic food chain for around 20 million years before the K-T event happened and the entire family was wiped out. According to Everhart:
"Mosasaurs ruled the oceans of the Late Cretaceous and were beginning to invade fresh water environments such as estuaries, swamps and rivers when the Age of Dinosaurs ended. Did they die suddenly due the catastrophic effects of an asteroid impact in the Yucatan, or was their extinction more gradual following the general collapse of the marine ecosystem? We may never know."
Everhart doesn't mention a third possibility, which is that they are still out there and we just don't know it. Seriously, don't go swimming in the ocean.
Thursday, November 6, 2008
I know some of you had a garden this summer. And you were probably thinking to yourself “Man, what the hell am I going to do with all these zucchini?” I’m grateful that so many people overplant, because lots of people gave me excess zucchini. However, I was eventually faced with a quandary about the best method of preservation.
I was thinking about the carbon footprint of different foods, and how the processing affects that carbon footprint.
For instance, if I walk out to my garden and pluck two tomatoes, and just slice one up and eat it, I’m not really increasing the carbon footprint of the tomato. If I take the other one and fry it, I’m obviously using more energy to cook it, and therefore I’m increasing the carbon footprint of my food just by the way I process it.
Thinking about this is actually pretty huge, and I’m going to focus in on one particular aspect of processing: Preservation.
I’m going to focus on peaches, because I preserved 25 lbs of them this summer using a variety of methods. Peaches can be canned relatively easily (without a pressure boiler), and can be frozen equally easily (adding a little anti-browning agent keeps them from turning dark). Figuring out the carbon footprint between different energy sources can be difficult, so to simplify things, I’m just going to compare electrical usage.
The equation should be pretty simple really. We want to estimate the energy used per day of storage via these different methods: The electricity used divided by the duration of storage. For canning, almost all of the energy use will be up-front, and the longer you store the cans, the better overall energy use rate you get. On the other hand, foods stored in the freezer will continue to cost energy as long as you preserve them, so long storage times will lead to bad energy efficiency.
So here's the data I collected for this little exercise. Basically, I needed to figure out the energy cost to keep a pint of peaches frozen. I used dedicated freezers because A) its a hell of a lot easier and B) I've been thinking about getting one. I've cut some of the significant digits off to make this a little more legible, and I'm not going to give you the brands of the freezers, because I don't think it really matters much.
|Energy per year||274||279||442||582|
|Energy per day||0.731||0.744||1.179||1.552|
|Capacity in cubic feet||6.8||7.2||14.2||15.8|
|Peach pints per cubic foot||59||59||59||59|
|Peach pint capacity||401.2||424.8||837.8||932.2|
|energy per day per peach pint||0.0018||0.0017||0.0014||0.0016|
|Peach pints per process||5|
|kW/h per pint||0.43264|
|# of Pints||15|
|Total energy for canning||6.4896|
Ok? So what does this mean? Like I said, the critical part here is how long you actually store the food. Let's take a look at a graph demonstrating this:
What we're seeing here is the estimate of energy use through time. Obviously, the canning doesn't change. Once you've done the canning, you're done. On the other hand, the freezer gets progressively worse through time. However, it takes a surprisingly long time for the freezer to get more energetically expensive. Between 8-10 months depending on the brand.
Obviously, there's a lot of wiggle in these numbers. My estimates on the freezer assume that the entire freezer is in use (if not for peaches, then for something) and if this isn't the case, then your energy cost per unit goes up. Let's look, for example, at a scenario where the freezers are operating at 80% capacity:
The other set of assumptions revolve around manufacturing costs and cleaning costs being approximately equal.
So now that I've identified all these problems, I'm a little less sure about my result. I think that if you already own the jars and the freezer, this analysis gives you an idea of how best to utilize them, but I think in terms of the original question, I'm going to have to dig deeper.
Thursday, October 23, 2008
The use of the scientific method has, to put it succinctly, completely revolutionized the modern human experience. However, the underdiscussed backbone of this method is its dependence upon two critical components: A larger scientific community and a generally honest set of scientists. The larger community is necessary to provide critical review and to duplicate results. The honest individuals are necessary to prevent tremendous amounts of time and effort from being wasted running down dead ends.
These two critical components have, on occasion, broken down. The primary question is: What can we learn from these cases of scientific misconduct?
Thursday, October 9, 2008
Regardless, last week I went out and did a mussel survey and relocation. A temporary stream crossing will be going across the Verdigris River, and we came to insure no mussels were harmed. In particular we were looking for the Ouachita Kidneyshell Mussel (Ptychobranchus occidentalis), and we were unsuccessful in finding it. We did find shells from 13 mussels, and live individuals from 5 (about 20 individuals overall), including a couple that are fairly rare. Hope you enjoy the pics:
The Verdigris River. If you look closely, you can actually see a lot of mussel shells on the stream-bottom and on the gravel bar even in this picture. There were literally thousands of mussel shells here.
A fairly common species, the Pistolgrip (Tritogonia verrucosa).
A smaller Pistolgrip and a White Heelsplitter (Lasmigona complanata complanata).
A Threeridge (Amblema plicata plicata). I got these confused with Washboard (Megalonaias nervosa), but I guess the key is the area where the ridges begin. In a Washboard there would be distinct 'patterning' there (the overall body shape is different as well). Incidentally, the three ridges are not characteristic (more ridges will form if the animal is given enough time to grow), but they were harvested for buttons only when they were large enough to have 3 ridges. These are thick, heavy shells that would probably make a lot of buttons.
We packed all the live mussels into a bucket and moved them upstream, so that erosion caused by the stream crossing wouldn't affect them. We also found some live Pimplebacks (Quadrula pustulosa pustulosa), Mapleleaf (Quadrula quadrula), and Bleufer (Potamilus purpuratus).
I didn't really dump them all in one location, but we forgot to take pictures of us putting the live ones back in the river. This is our 'creative recreation' of the event.
Thursday, October 2, 2008
Wednesday, September 24, 2008
There is no more obvious face of American environmental problems than the cow. In the name of cattle production the American farmer has damned up streams to create livestock watering opportunities, ripped out native grasses to plant brome and fescue, plowed under wetlands and riparian lands to plant alfalfa and hay, and concentrated them into a location so densely that rainwater becomes lethally toxic. Cattle production (or maybe just farming in general) is probably directly responsible for more species becoming extinct than any other human activity in North America.
But that doesn't mean the cow itself isn't a fascinating animal with a cool story. The scientific name of the cow is Bos primigenius (at least, that's my understanding...there's some taxonomy confusion here), and it was first domesticated back in the 6th millenia BC in Mesopotamia. The original animal is known now as the Aurochs and holy god is it a cool animal. Aurochs once roamed basically all of Europe and Asia, and were independently domesticated at least 3 times. This is particularly amazing if you read the following account by Caesar about the aurochs in Germany:
Gallic War Chapter 6.28, "...those animals which are called uri. These are a little below the elephant in size, and of the appearance, color, and shape of a bull. Their strength and speed are extraordinary; they spare neither man nor wild beast which they have espied. These the Germans take with much pains in pits and kill them. The young men harden themselves with this exercise, and practice themselves in this sort of hunting, and those who have slain the greatest number of them, having produced the horns in public, to serve as evidence, receive great praise. But not even when taken very young can they be rendered familiar to men and tamed. "
I've never seen much written about animals using domestication as a life-history strategy, but this is one species where it has obviously been an advantage. The domesticated aurochs (i.e., cattle) began wiping out the wild aurochs almost immediately. Humans found cattle to be incredibly useful animals: You can hitch your wagon to one to pull things, you can feed it grass and it will produce milk, and killing even a single adult will give you enough food for months. As a result, humans agressively aided the expansion of cattle at the expense of aurochs. The last known aurochs lived in Poland and were 'protected' by royal decree. Nevertheless, the last individual died in 1627 and its skull currently resides at the Livrustkammaren in Stockholm. Two brothers, Heinz and Lutz Heck, had the bright idea of recreating the aurochs back in the 1920s (oddly enough, as part of a Nazi propoganda campaign). Theoretically, this might be possible if all the original genes are still around, you would just need to combine them. The results of these efforts are the Heck cattle, and man, you need to look into this yourself, because there is no end to the awesome (see awesome picture below).
Modern cattle have been developed into distinctive breeds for different purposes. In the United States, a federal grading standard in 1927 somewhat stupidly lead to meat quality becoming associated with 'marbling', and so breeds like Angus and Hereford have been the ideal. Marbling was considered important primarily because it made farmers more money. Marbling happens because grass fed cattle are 'finished' on a grain-heavy diet. In particular, a guy named Alvin H. Sanders, editor of Breeder's Gazette, promoted this idea so strongly that it caught on with the Department of Agriculture. The stated purpose was to promote meat that was of high quality culinarily, but as it turns out, marbling contributes relatively little to the overall tenderness of cooked meat. The U.S. eventually altered the grading system to lessen the importance of marbling, but is still one of only three countries in the world that grade beef on fat content (Japan and Korea are the others).
Cattle are generally slaughtered between 15 and 24 months in the U.S. (usually closer to 2 years), while in Europe the slaughtering times vary with the culinary traditions (Italians: 16-18 months; 3-4 years in France and England prior to prion diseases). Generally these variations have to do with the toughness of the meat and the flavor, although a lot of both has been sacrificed on the alter of efficiency. For instance, most culinary applications value the flavor of grass-fed beef, yet in the U.S. the economies of scale and a traditional over-abundance of cheap corn have resulted in massive feedlots where cattle are raised for 4-8 months on grain instead of grass.
I've never eaten veal and I can't honestly say I see the appeal. Veal is essentially beef that tastes and feels nothing like beef. The longer an animal uses its muscles, the tougher and more colored the meat becomes. Veal are usually confined so they can't move and slaughtered before ever given a chance to eat solid foods. The result is meat that is pale, extremely tender, and delicate in flavor. My feeling is that if you want to eat pork, just eat pork!
Because cattle are so closely associated with humans, there is ton more information out there: Their relationship to other ungulates, the amazing amount of fish kills that they caused prior to the clean water act, and their impact on rangeland birds are all interesting topics. However, I just got back from vacation and this is all I'm going to write today.