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From Carnivore to Herbivore
smooth wombat wrote in to mention an a recent discovery in the field of evolutionary biology. From the article: "A surprising discovery in Utah has paleontologists scratching their heads and asking: Why would a carnivore evolve a herbivorous diet? The species, christened Falcarius utahensis, belongs to a dinosaur group called the therizinosauroids. These are mostly thought to have been plant eaters. But the recently discovered fossil, the most primitive therizinosauroid found so far, seems to have survived on a mixed diet of meat and vegtables...The switch to vegetarianism is surprising, says Paul Barrett, who studies dinosaurs at the Natural History Museum in London. The therizinosauroids belong to a larger group of dinosaurs known as theropods, and many of these are known to have been excellent at catching a meaty meal. "
Not just vegetarian, but omnivorous.
"Although the team cannot know whether Falcarius was a committed vegetarian - it may have eaten a bit of meat, too - its emergence did coincide neatly with the evolution of flowering plants."
Why evolve to eat plants and animals? I dunno, but it works for me too!
"At the same time Falcarius appeared, the world was changing greatly because flowering plants were appearing," Dr Sampson said. "They would have provided a new food source. It could be that Falcarius was exploiting an open ecological niche."
That would make it an omnivore, not an herbivore.
An herbivore relies ONLY on vegitation for sustinance, as an omnivore has a mixed diet.
>>As you go up the food chain, you get less energy >>from the meat.
There are a couple of other trade-offs involved that make it less simple. "Pure" energy is converted less efficiently into meat, yes. But digesting meat as opposed to vegetables can be easier (less celulose) and allow simplification of digestive structures (drop the appendix, ditto multiple stomachs). Meat converts more efficiently into energy. Herbivores have to eat in bulk and spend most of their time foraging or digesting. Carnivores can go longer without food. But they have to hunt the stuff down.
I don't think this is confusing either - the balance can tip either way based on circumstances.
That's not quite how it works. Plants have to photosynthesize enough to grow and maintain "operations," herbivores have to eat enough plants to grow and maintain "operations," etc. Eventually a top predator is ultimately eating a lot of plants more because there are a lot of middlemen.
As you go up the food chain, you get less energy from the meat.
There's generally more energy in meat, and it's denser so you spend a lot less time eating meat calories. Of course, finding and killing that meat is a different story. I expect the answer to our question is one of relative scarcity or competitive ability - perhaps a different predator took away the market?
But it's not one of energy density, most definitely.
No mammal or reptile is strictly a "vegetarian". None of these animals can convert cellulose into glucose, they ALL require bacteria to do this for them. It is obvious why some animals evolved to eat plants: there simply wasn't enough meat available for them to consume. Over time, their bodies evolved adaptions such as larger and multiple stomachs to regulate the gas biproducts of bacterial decomposition of cellulose. This is why humans have to cook their food, we simply cannot survive on a truly natural vegetarian diet. Our stomachs are too small.
Without exception, all animals can eat meat. Even the cow retains the ability to produce bile acids to break down fat, the primary source of energy for most predator mammals.
I don't read or respond to AC posts
So do Koala Bears, and they only eat leaves. Which proves what?
>alleviate the deficiencies in Vitamins B12 and D
Vitamin D is a hormone you synthesize in your skin from exposure to ultraviolet light (usually from the Sun). You might be interested to know that Vitamin D is ADDED to milk as a supplement.
B12 is from bacteria in soil. Historically it was also present in running water as it erodes soil. Modern agriculture depletes topsoil and consumers over-clean produce; historically you would eat a little dirt and thus get the B12, which has an RDA in MICROgrams.
Staying indoors and avoiding dirt are both side-effects of modern living, but evolutionarily, there is no reason being a plant-eating human would cause a deficit of these nutrients.
Modern life makes up for shortcomings with a pill. So, take your pick.
Whales are carnivores, eating krill and other small animals. Sea lions are carnivores, eating fish. Killer whales eat them both.
Dog, cat. Yes, not here, but in other parts of the world, they do. Many fish eat other fish. Grilled shark is a good reason to not be vegetarian for a few days for me. =)
veganism is a LOT harder than straight vegetarianism -- access to dairy and eggs makes everything a lot more straightforward, and problems with energy levels are much less common (in fact if you suffer from that, you're clearly missing something). however, you can get veggie B12 from nutritional yeast (saccharomyces cerevisiae), which you can take as supplement, fortified cereals, and fortified (soy) milk.
i've been vegetarian --no meat, no fish-- for 18 months now, and to bo honest it's very easy to get a good balanced diet. you just need to do a little bit of research first so you don't make the classic mistakes (eg: replace a lot of the meat with dairy/cheese as this inhibits vitamin uptake).
still, no plans to go vegan -- the potential pitfalls, as it seems your sister found out, are much larger.
10 years as a strict vegetarian with no supplements and mostly eating my vegetables raw (and university life taught me to eat only once a day to save time,) still alive and kicking, but I guess I shouldn't be alive or should be a nervous wreck by now? Hmmm.
You can't handle the truth.
"Now I am not an authority on this, but vitamin B12 is only found in amounts sufficient for our dietary needs in animal products like meat, fish, eggs, and dairy and is essential for proper nervous system function."
Yes, and animals get their B12 from microbes! Animals *cannot* make B12! We all must get B12 from our diet, it just so happens that our society makes it easiest to get B12 from animal products.
"If you're one of the "strict" vegetarians out there you must supplement your all vegetable diet with B12 or run the risk of developing nerve damage or neurological disease (among other complications). You cannot meet all of your dietary requirements from an all-vegetable diet unless you take supplements."
If by 'take supplements' you mean consume special non-food items (e.g. pills), then you're wrong -- you can find B12 in many fortified food items (plant milks, breakfast cereals, etc.). And to those of you who call this 'special' food, what about all of the fortified foods that you meat-eaters consume? (iodized salt, vitamin-D fortified milk, etc.)
To those who say that it's not possible to be vegan on 'natural' foods, please keep in mind that this is largely a result of our modern lifestyle and food-processing practices. Vegetarian animals (e.g. cows) get B12 from mucking around in the dirt, eating dirt that clings to grasses and other plants, etc. We sterilize our fermented food products, wash our vegetables, etc. for good reasons, but, as a consequence, lose direct access to these microbes.
"While I would agree that a vegetarian diet is certainly healthier than what most people eat, the fact is a balanced diet from all the food groups including animal products is not only wise but absolutely necessary for a healthy human body. If my memory of biology class is correct just about every herbivore has to eat an enormous amount of plant material to sustain themselves, with specialized digestive sytems. Why do you think a cow has four stomachs?"
For one thing, these animals can't cook -- there are lots of nutrients in plant foods that aren't bioavailable unless cooked (sometimes cooking still doesn't help -- e.g. oxalates). At any rate, I only have one stomach, and I'm doing just fine.
"I watched my sister fade away on a stict vegan diet and even with supplements it wasn't enough. She re-introduced a weekly serving of meat and noticed a huge improvement in her mood and energy level. Her experience taught me that a balanced diet is more important than focusing on any one particular food group and my diet is the better for it."
If it's the re-introduction of meat that did it, then I'm betting it was iron -- women have an increased need for iron, and the form of iron in most plant foods (Fe3+; iron(III)) is just *not* soluble enough in water (at physiological pH) to be absorbed by the body. Consumption of Vitamin C with non-heme containing iron foods is one way to solve this problem (VitC donates an electron to it, forming Fe2+, which is *much* more soluble in the body, and this is actually one of the reasons Vitamin C is considered an essential nutrient (various enzymes that need Fe2+ also need VitC to stick around to keep the iron reduced)).
The society we live in doesn't support vegans (though it has been getting better), so I'm certainly not arguing that being vegan is easy, but these arguments that say that it's impossible or unnatural are ridiculous!