View unanswered posts | View active topics It is currently August 2nd, 2014, 9:34 am



Reply to topic  [ 43 posts ]  Go to page 1, 2, 3  Next
 Omnivores or Herbavores? 
Author Message
User avatar

Joined: August 9th, 2008, 9:23 pm
Posts: 32
Location: California
Hey gang,

It seems there is a lot of conflicting information on the Internet about whether we are "natural" herbavores or omnivores. What is your opinion, based on what you have read on the subject?

Regardless of the answer to this question, I will remain a vegan - for ethical reasons. Whether or not it is "natural" for us to eat meat, the fact is we do not need any animal products in order to survive and live well, so I choose to abstain. However, this is a subject that comes up quite often in discussions on the topic of vegetarianism, so perhaps one should stay well-informed.

I'd appreciate your input. Thanks,

Rami


August 13th, 2008, 7:47 am
Profile
User avatar

Joined: February 27th, 2008, 1:17 pm
Posts: 2976
Location: Greater London
I confess that I'm inclined to answer "omnivores, of course", without hesitation. But maybe I need to think about it a bit more. Can terms like "omnivore" or "herbivore" be applied to modern human beings, whose diets are determined in a way that's so unlike any wild animal's diet? When cattle were routinely fed meat-and-bone-meal in the UK (before the 1996 ban), were cattle still herbivores, or is it pointless to apply such a term to an animal that isn't free to choose its own food from among the options that "nature" provides? Not that the diets of human beings are controlled in the same way that livestock animals are, of course, but our diets are to such a huge extent culturally determined, and have been for many centuries, that it's hard to detect a "natural" diet in all that.

And then there's the whole question of what "natural" means. The term is usually used in distinction to "man-made" or artificial or synthetic, and since a large proportion of what we eat has been, at the very least, altered by human beings, through selective plant and animal breeding, for example, or through at least some processing, can it be said to be "natural"? If we argue that human beings are part of nature, so everything we do must be natural too, then the word "natural" becomes meaningless. So if we want to continue using the word, where do we draw the line? Is flat bread natural, but not Twinkies? Is palm wine natural, but not Coca Cola? Pff! I don't know.

Still, I suppose it's possible to look at human societies that are at least closer to nature — extant hunter-gatherer societies (or hunter-gatherer societies that were until fairly recently extant). It may be that many of them would be more accurately described as gatherer-hunters, since hunted meat is a smaller proportion of their diet than gathered plants, but then there is the exception of those living in the Arctic region, who barely gather at all. And it does seem that all of them eat some meat and some plants. Which makes them all omnivores. Does that mean that that's true of the species as a whole? When these societies represent a tiny and shrinking proportion of the global human population, can they stand in for "natural" humans? Are they our dietary representatives? No, that doesn't make much sense to me.

Still, whether or not it's helpful to talk about modern humans as being "natural" omnivores — or "natural" anything else — I don't think it's unreasonable to argue that at some point in the evolution of Homo sapiens the species became omnivorous. There seems to be plenty of evidence that early hominids ate meat (see, for example, "Meat eating is an old human habit", New Scientist) and that our palaeolithic ancestors ate meat (see, for example, "Animal v. plant foods in human diets and health: is the historical record unequivocal?", by Marion Nestle) — though admittedly it's impossible to determine what the proportion of animal to plant foods was in their diet. We've continued to evolve since then, in any case, and we're still evolving, though I'm not sure what role, if any, natural selection still has in the evolution of the human diet.

Like you, Rami, I choose my diet because I think it's more ethical, rather than because it's more natural. And I would not use arguments about what a "natural" diet is for humans to persuade others to reduce their consumption of animal foods. I suspect, and certainly hope, that the proportion of animal to plant foods consumed by the world human population will decrease in the future, for the sake of humans, other animals and the planet, but I think it highly likely that animal foods of some kind will remain a part of the diet of most human beings for as long as the species is around.

Anyway, those are my immediate, and rather muddled, thoughts. What are your own views on the question, Rami?

Emma


August 13th, 2008, 12:05 pm
Profile
User avatar

Joined: July 4th, 2007, 10:10 am
Posts: 9159
Location: Darkest Kent
A very thought provoking response from Emma as always. My initial thought is that the concept of there being a 'natural' anything is a bit misleading. We humans have evolved according to our surroundings (amongst other things). If we could not tolerate meat, or it were unavailable, we may have evolved differently. It seems to me that humans have evolved to eat a whole variety of foods, and choose their diets according to what is available, be it jungle, the sea-shore, prairie or Tescos. There are also occasions where our diet may be influenced by a 'misfiring' of evolution. Kiddies' sweet tooth, perhaps evolved to encourage them to eat fruit, but today instead encourages them to eat sweets, which represent some sort of 'super-fruit'. (I think Desmond Morris has something to say about this in The Naked Ape.) Also, diet is likely to influence our health. To what extent is it 'natural' for us to live into old age? In the Flintstones movie, Barney Rubble asked Fred Flintstone if it was wise for him to eat Brontosaurus-burgers, to which Fred replied, "Don't be silly, Barney! My father eat Brontosaurus-burgers, and he lived to 30!"

I think one can discuss diet in terms of its influence on the human body, and ethically, as you have chosen to do, but if a 'healthy' diet leads to old age, long past real usefulness to the group or tribe, can it really, in evolutionary terms be described as 'natural'?


August 13th, 2008, 1:07 pm
Profile
User avatar

Joined: August 1st, 2008, 11:54 am
Posts: 209
I'd like to take the opportunity to link to an article by Stephen Fenwick-Paul who used to be on this forum,

http://www.humanist.veggroup.org/articl ... ianism_572


August 13th, 2008, 5:41 pm
Profile
User avatar

Joined: August 9th, 2008, 9:23 pm
Posts: 32
Location: California
Quote:
"Emma Woolgatherer"]I confess that I'm inclined to answer "omnivores, of course", without hesitation. But maybe I need to think about it a bit more. Can terms like "omnivore" or "herbivore" be applied to modern human beings, whose diets are determined in a way that's so unlike any wild animal's diet? When cattle were routinely fed meat-and-bone-meal in the UK (before the 1996 ban), were cattle still herbivores, or is it pointless to apply such a term to an animal that isn't free to choose its own food from among the options that "nature" provides? Not that the diets of human beings are controlled in the same way that livestock animals are, of course, but our diets are to such a huge extent culturally determined, and have been for many centuries, that it's hard to detect a "natural" diet in all that.

And then there's the whole question of what "natural" means.


I think when people talk about whether it is natural for us to eat meat or not, they mean "are we designed" to eat meat, or "have we evolved to eat meat." Again, to me, personally, it does not matter, but it is an issue that many people consider relevant.

Quote:
Still, whether or not it's helpful to talk about modern humans as being "natural" omnivores — or "natural" anything else — I don't think it's unreasonable to argue that at some point in the evolution of Homo sapiens the species became omnivorous. There seems to be plenty of evidence that early hominids ate meat (see, for example, "Meat eating is an old human habit", New Scientist) and that our palaeolithic ancestors ate meat


If that is true, then that's our answer right there.

Quote:
Like you, Rami, I choose my diet because I think it's more ethical, rather than because it's more natural. And I would not use arguments about what a "natural" diet is for humans to persuade others to reduce their consumption of animal foods.


I agree. I do not like that argument and I do not like to use it in discussions on veganism.

Quote:
I suspect, and certainly hope, that the proportion of animal to plant foods consumed by the world human population will decrease in the future, for the sake of humans, other animals and the planet, but I think it highly likely that animal foods of some kind will remain a part of the diet of most human beings for as long as the species is around.

Anyway, those are my immediate, and rather muddled, thoughts. What are your own views on the question, Rami?

Emma


I'm glad you asked....


August 14th, 2008, 8:37 am
Profile
User avatar

Joined: August 9th, 2008, 9:23 pm
Posts: 32
Location: California
Until recently I was a regular poster on a vegan forum. I was kicked out. I dared assert that humans are omnivores, that the human species is adapted to eating meat. The forum administrator accused me of promoting an omnivorous ideology. He was of the firm opinion that humans are natural herbavores, and that, even though one does not have to believe that to be a vegan, opining that humans are natural omnivores is somehow working for the other side. The whole experience was very negative and unpleasant and has been bugging me ever since.

I do think that humans have evolved to be omnivores. I do think, based on the evidence I have read, that meat is unhealthy for us. I do think that a vegan diet is healthier than an omnivorous diet. But that is not evidence that we are natural herbavores. In evolution, the "goal" is ot make it to the point where you can pass on your genes. To assert that we are natural herbavores is (correct me if I am wrong) to assert that eating meat would be lethal to us early on and would kill us before we have had a chance to pass on our genes. You know what I mean? If eating meat did not kill us before we produced progeny, if meat was actually nutritious to us, then it follows that we are adapted to eat meat. Again, in evolution the only thing that matters is whether or not we get to pass on our genes. Evolution does not care whether we are healthy in our 70s; it does not care about us making it to old age. It only "cares" whether we get to pass on our genes. So, it could be that a lifetime of eating meat would contribute to all kinds of health issues later on in life. But this has nothing to do with evolution. By the time we develop heart disease, most of us have already passed on our genes.

Furthermore, our prehistoric ancestors lived in a world in which they are always on the brink of starvation. It is reasonable to suppose that eating meat, providing them with energy, protein, etc. staved off starvation and thus had a survival value. So, I think it is a no-brainer: we evolved as omnivores. If we had not, we probably would not have survived. And again, this has zero effect on my vegan ideals.

However, this was my first time dealing with what I would call dogmatic veganism. The forum administrator viewed my position as a challenge to veganism. On another thread I had asked "What are the best argument for adopting an omnivorous lifestyle?" I had made it clear that I wanted to know what were the most reasonable, most sophisticated arguments in favor of consuming animal rights - because I wanted to be better at debating non-vegans. This was also seen as a covert promotion of my "ideology".

It almost felt as if I was "blaspheming" and that my questions were acts of challenging vegan "orthodoxy". And so the vegan pope had me excommunicated. Oh, it did not help that I had posted a whole bunch of posts criticizing religion, which ruffled quite a lot of feathers. Interestingly enough, it was not theists that were offended by what I said, but agnostics and atheists!

Anyway, reason, not veganism, is paramount to me. Veganism, as of right now, is what reason has led me to. I do not treat veganism as the end product. If in the future reason leads me elsewhere, terrific. But I refuse to become a dogmatic vegan. And I think this is what the problem was on that forum. I was seen as challenging the dogma of veganism - that not only is veganism ethical, healthy and environmentally conscientious, it is also "natural". I think it is much more important that we stay reasonable, than we adhere to some kind of convenient dogma that satisfies our confirmation boas.

So, that's my story... I am happy to be posting here because I see that there are a lot of reasonable, free-thinking people here, who simply do not do dogma.


August 14th, 2008, 9:15 am
Profile
User avatar

Joined: July 3rd, 2007, 10:26 pm
Posts: 15190
In today's Scotsman
Quote:
********************************************************************************
Scrap animal farming to make a real difference - The Scotsman
http://thescotsman.scotsman.com/letters ... id=4388584
~~~~~~~~~~~~~~~~~~~

Scrap animal farming to make a real difference

Dorothy H Crawford, professor of medical microbiology and assistant principal for public understanding of medicine at the University of Edinburgh, suggests research into the reduction of methane production in cattle will solve the problems identified by the United Nations Food and Agriculture Organisation's (Unfao) document Livestock's Long Shadow (Science & Environment, 9 August).
However, her analysis of the damage done by livestock to the global environment is superficial. None of her suggestions for reducing methane emissions will affect the produced by UK livestock, the enormous waste of good farmland which livestock require to produce meat and milk or the vast quantities of water livestock need for their subsistence.

According to the Unfao, livestock contribute 18 per cent of global greenhouse gas emissions – so, as globally moral individuals, we should obviously stop killing animals for food to reduce this to zero – then worry about the other 82 per cent from industry, housing, transport etc.

Prof Crawford declares that "we are rightfully proud of British dairy products". I don't share this pride; what is there to be proud about in killing animals for pleasure? Dairy, meat and eggs are an irrelevance to our human dietary needs because we can source all the food we need from plants without needlessly killing animals.

Prof Crawford's analysis of the problem of methane production by cattle lacks rigour because it fails to take an objective and scientific overview of the clearly anachronistic and woefully inefficient role of livestock in modern farming.

JAMES BOYLE
Glazert Road
Dunlop, East Ayrshire


1
jj veritas,
14/08/2008 04:03:01
Wild buffalo, zebra and other grazing animals don't produce much methane. Farmed cattle fed on processes foods, silage and unnatural junk, however, bubble it out constantly until despatched 2.5 years into their 30 year natural life expectancy. Draw your own conclusions.
Report Unsuitable
2
Beth Boyle,
NY 14/08/2008 05:56:04
It's a reflection of modern agriculture. Go back to letting animals graze as they were meant to. We don't need less cows we need less factory farming in this world!
Report Unsuitable
3
Colin Wilson,
Aberdeen 14/08/2008 06:37:33
"...the enormous waste of good farmland which livestock require to produce meat and milk or the vast quantities of water livestock need for their subsistence."

Actually, in Scotland there are large areas of farmland that are unsuitable for any form of food production except for rearing sheep for their meat and wool. Nature provides the water, abundantly.
Report Unsuitable
4
Dave from Barra ©,
Western Isles 14/08/2008 08:33:54
Speaking in context of Scotland (and with ref to Colin above), where is all this "good land" that livestock is raised on?

Most of Scotland beef and lamb is raised on marginal land that couldn't produce any arable produce. In effect, it is an efficient way to produce food on land that is good to grow monoculture heather.

Now, speaking in terms of arable, how much methane is released from gash crop that doesn't make it into the human food chain (i.e. as it sits and rots?) Wouldn't it be better to feed that gash crop (around 50% for organic arable crop) to animals?

Also, what about the CO2 produced in making the ferts, chems, diesel etc to plant, raise and harvest these crops? (BTW, organic is chronic for CO2 production)

JJveritas @1 is making wild statements, especially the first sentence which is on something he could never prove to us. Basically, the animals he mentioned are ruminants like our own livestock and produce as much methane as a grass finished cow here. He must be a veggie and alos doesn't understand farming systems in Scotland or elsewhere. BTW, vegeterians produce more methane than omnivores. Go figure.
Report Unsuitable
5
Southern Badger,
14/08/2008 11:55:48
Hey, massive treeless, hedgeless grain prairies covering the whole of the countryside! What a good idea! Well done, veggies.
Anyway, if we all turn vegetarian we'll all produce more methane (apparently I'm not allowed to use the f**t word here) then we're back at square one...
Report Unsuitable
6
James F,
East Ayr 14/08/2008 12:32:40
Beth #2.
You're right that we don't need factory farming but you're wrong about the need for livestock; we don't need cows and they waste an enormous amount of good land.

It's wrong to kill animals purely for pleasure and once you come to terms with the fact that you can feed yourself on a really good, healthy diet without animal produce then you are in a moral dilemma. I don't think you're prepared to face up to that dilemma.
Report Unsuitable
7
James F,
East Ayr 14/08/2008 12:44:06
Colin #3
Consider the North American prairies where half the wheat grown is fed to cattle (or the Amazon rainforest where the trees are being felled to grow soya beans to feed cattle). If you miss out the cattle bit, you can feed an awful lot more people or produce more biofuel as necessary. Cattle ar 700% inefficient as convertors of grain into meat.

Animal farming is unneccesary; full stop. Land in Scotland which is unsuitable for pasture and/or arable (and one suspects there is a lot more land that could be used for arable than is the case at present) could usefully be used for afforestation, biofuel, windfarms.
Report Unsuitable
8
Guga II,
Rockall 14/08/2008 15:13:25
These veggies need to go away and plany themselves.
Report Unsuitable
9
James F,
East Ayr 14/08/2008 15:19:34
GugaII #8

These dumplings need to revise their spelling/typing skills.

Just because you haven't got the intellect/patience to understand the argument doesn't make you a bad person.
Report Unsuitable
10
James F,
East Ayr 14/08/2008 15:23:51
#5 Badger

Don't think people produce methane. We haven't got the ruminants' digestive system.

Besides, it takes ten times as much cows'pigs/sheep to feed a person as it takes potatoes/carrots/avocadoes. But I guess you knew that.
Report Unsuitable
11
James F,
East Ayr 14/08/2008 15:28:05
Dave #4

You seem to be saying we should do farming in a more intelligent way; I totally agree. First step is to take animals out of the food chain - they are enormously wasteful. If you have land which is difficult to grow crops on, plant trees - we've been here before.

Where do you get your stuff about people and methane?
Report Unsuitable
12
nabodican,
Rural Scotland 14/08/2008 17:35:45
James Boyle is clearly a veggie fanatic who wishes to go against nature. While he is entitled to his opinion, I would not imagine that anyone is going to listen to his extreme view.
Nature made us carnivores - end of story.
Report Unsuitable
13
Jock Tamson,
Scotland, Caledonia, Alba 14/08/2008 17:41:04
Humans are omnivors. Animals exist as part of the food chain. Animals eat animals. Humans are also animals.

10, James. If you don't think humans produce methane then you have never been in the army. We used to light a candle on a bedside locker in the middle of the barrack room some nights. When you so desired, you got out of bed, approached the candle backwards, dropped your jammies and passed wind into the flame of the candle.

Whoever got the biggest flame was the winner.

But lets kill all the cattle on earth. Wow, what a bargain we'd have for the glut of milk, leather goods and meat until it ran short.
Report Unsuitable
14
James F,
East Ayr 14/08/2008 19:04:49
#13 Jock

Thanks for that. Turns out, as you say, humans can produce about 10ml of methane a day; cows about 200 litres.

You may be thankful that you didn't share your living accommodation in the army with cows; blow torch time.

The milk, leather goods and meat don't run short; they just get replaced by other goods. Simple really - and less messy.

[Retrieved: Thu Aug 14 2008 19:52:26 GMT+0100 (GMT Daylight Time)]

###################

_________________
Alan Henness

"We're all in this together, but some are more in it than others."
— Me, with apologies to Napoleon


August 14th, 2008, 7:53 pm
Profile WWW
User avatar

Joined: July 4th, 2007, 3:35 pm
Posts: 10234
Location: Shetland
Quote:
From Alans post above
Actually, in Scotland there are large areas of farmland that are unsuitable for any form of food production except for rearing sheep for their meat and wool. Nature provides the water, abundantly.
Report Unsuitable
My bold.
I think I've already had this debate, with clayto and others.

If you removed all the animals that are providing food, from all the land that is no good for growing crops, you leave a very big hole in the food chain.

_________________
Abstinence Makes the Church Grow Fondlers.


August 14th, 2008, 8:59 pm
Profile
User avatar

Joined: July 4th, 2007, 10:10 am
Posts: 9159
Location: Darkest Kent
IMO, James Boyle is a pompous ass. I could comment, but I'm tired and he won't read it. And even if he did, he wouldn't change his mind. :cross:


August 15th, 2008, 11:57 pm
Profile
Died May 2009 R.I.P

Joined: July 28th, 2007, 10:34 am
Posts: 184
Regarding Nick's question about why children are drawn to sweets then it may be that it is because human milk is sweet and not very fatty.

When a mother decides not to feed her infant on her own milk then she has to use a formula which is modified to have the correct nutrients for her baby it wouldn't be good for the child for her to use cows milk which is unmodified. I am not sure if she could use pig's milk unmodified or not it hasn't been customaryd to use pigs for milk. I do not think goats milk is sweet enough and sugar may have to be added.

It is difficult to know what to do.

I ave to say I find it difficult to stick to plant foods and do eat free range eggs. Maybe one day we will be able to live on air and not have to use anything else.

_________________
There'll be blue birds over
The white cliffs of Dover


August 16th, 2008, 10:43 am
Profile
User avatar

Joined: March 14th, 2008, 9:59 pm
Posts: 38
Hi there :wink:

I think it is reasonable to believe that humans have evolved via eating meat and that we show evidence of selective evolutionary pressures from the past in the form of our teeth and digestive system today. But we also evolved via eating mainly soft foods such as fruit.

Since it seems arbitrary to pick one period of evolutionary time as being more important to determining our "nature" than another in this context I would not say that humans are "naturally" carnivores or herbivores.

So looking at what our ancestors did does not for me answer the question of whether humans are naturally carnivores or herbivores or omnivores. Something more is required.

One way of adding that something more would be to give an Evolutionary Psychology perspective on human nature and say that there is evidence that current humans have a
specialised module that deals with information regarding the selection of food choices by desires for certain foods. This would be innate rather than learnt. [I think it is important to say what "natural" is to be contrasted with otherwise it gets a free-ride in the debate and ends up meaning anything the author wants it to mean]

After all it is how the past impacts on current humans that makes something natural or not. This is contrasted with what the more simple this is what our ancestors did, so it is natural for us to do this line of approach that is sometimes taken.

However I do not think there is any evidence for such a mechanism that is widely shared by current humans for controlling desires to eat meat that would make desire for eating meat natural and desire for eating non-meat products learnt.

Instead there seems to be a very general desire for sweet food and food high in calorie content (both of which are manipulated by contemporary consumer society in the form e.g. chocolate or donoughts). I don't know if there is a term for a "natural" chocolate or donought eater although I doubt it is a serious debate. :-)

So from my perspective the evidence looks like being in favour of the view that we are naturally omnivores aka "designed" to be omnivores from an evolutionary perspective. It also strikes me as making a lot more evolutionary sense too as it makes humans far more adaptable to changes in the environment. So at the moment I agree with Rami

Still if anyone has any evidence to the contrary then I would like to read it.



*"Design" in this context meaning something like current abilities formed under evolutionary pressures that make us specially adapted to eating a variety of meat/non-meat food stuff.


P.S.
I enjoyed the other posts and links too :-)


August 20th, 2008, 10:44 pm
Profile
User avatar

Joined: August 30th, 2008, 3:31 pm
Posts: 66
As a species humans are omnivores within the carnivore, omnivore, herbivore spectrum. It is correct to say this because many of us do, in fact, eat meat and many of us do eat plant foods. In moderation these things do not generally poison us and our bodies are equipped to derive nutrition from both animal and plant food sources.

An important area of confusion, I think, lies in the notion of being omnivorous confusing with what it means to eat a "balanced" diet. Eating a balanced diet means obtaining a balance of the nutrients that are needed to sustain the body and for it to thrive. This can be accomplished via a plant based diet that includes some animal products or via a diet consisting entirely of plant foods. The problem with the common usage of the label "omnivore" is that it suggests a mid-point between carnivore-ism and herbivore-ism that many take it to mean that one should eat both animal and plant products.

In fact, plant sources are more than sufficient to supply our macronutrient needs and are absolutely necessary in order for us to obtain necessary micronutrients. Animal products are entirely unnecessary in our diets and certain plant products are absolutely mandatory. So whilst it is technically correct to assert that the human species is omnivorous, we are more so scavengers than we are predators and our nutrient needs lean us substantially more toward the herbivore side then the carnivore side.


October 6th, 2008, 3:45 am
Profile

Joined: July 22nd, 2007, 6:34 pm
Posts: 384
I pretty much agree with what has been said throughout this thread, including the recognition that we have evolved as omnivores and the scepticism about the use / misuse of the term 'natural'. The fact (so it seems) that we are omnivores and can live satisfactorily on a range of different diets is to me very relevant to the association between humanism and vegetarianism because it means we can and do make choices. We cannot realistically choose what to breath but we can (depending on culture / economic circumstances etc) choose what to eat and drink. Vegetarian Humanists may make that choice on a range of criteria including personal health, environmental / economic concerns (of growing importance), taste, aesthetics and culture ----- and for many of us, most importantly morality / ethics (in my case largely derived from the extension of Utilitarian principles to non-human animals). If we were 'naturally herbivores' (for want of a better expression) that would be OK by me but we would not be involved in making ethical choices with regard to that aspect of our lives ---- so it would not be an issue of particular relevance to humanism / Humanism.

I have no problem with the idea that humans and pre-humans developed as meat eaters (although this link refers to recent work casting doubt on meat eating as a factor in early brain development ----

http://news.bbc.co.uk/1/hi/health/6983330.stm ---)

but evolution is about change, not about staying as we once were. Recently I gather, there has been evidence that some (all?) Neanderthals were cannibals and that our genes are mixed with theirs. If it proves to be well founded it would hardly gain much favour as an argument that it would be 'natural' for us to become cannibals again.

Rami --- I expect in the light of your experiences on a Vegan forum (link?) you find things different here with pro-veg, anti-veg and even anti-HVG posters! I take part in some VegSoc forums / egroups where I would not expect to see anyone treated the way you describe ----- and I expect the same would be true of VeganSoc? Incidentally, The Vegan Society Head of Information Services is a supporter of HVG.

Chris

_________________
clayto


October 6th, 2008, 4:11 pm
Profile
User avatar

Joined: September 13th, 2008, 9:15 am
Posts: 1474
Location: Forest Hill, London
Humans are clearly omnivores based on numerous lines of observable evidence. Rami, I applaud your rational stance! I would also say to Chris that cannibalism crops up time and again in human societies, so with the right social conditions I don't see why it wouldn't crop up again (if it were socially permitted I'd tuck into the flesh of my enemies with gusto).

The concepts of herbivory, carnivory and omnivory are interesting subjects in their own right, since few animals are totally restricted in their usual diet and most will make use of other animal tissues where they can, since it provides a much more concentrated source of nutrients than plant material. Only ruminants are exceptionally well adapted to a herbivorous diet due to their complex multi-chambered stomachs that allow symbiotic bacteria to break down cellulose, with mechanical assistance from repeated chewing of the cud to speed the process. Despite the efficiency, ruminants typically need to graze and process food for about 18 hours a day.

Non-ruminant ungulates are rather less efficient, so they eat more and process less (compare horse dung to cow dung to get an idea of digestive efficiency). Rabbits have a novel way of double processing their food to get more nutrients out, they crefecate, where they produce moist round droppings that are left for a while for bacteria to get established, then they are re-eaten to absorb more nutrients. The second passing is dry and hard, with much less nutritional value. Other herbivores tend to either be very large (most important being a large stomach), eat constantly or have a very low metabolic rate, so they are slow and use less energy. Gorillas are big, they eat almost constantly (as a result they have impressive buttressing of the skull to cope with the forces involved in all that chewing) and they tend to engage in little unnecessary activity.

Granivores and frugivores have a diet which is composed of the more energy rich fruiting bodies of plants. Such animals tend to also be a bit more cosmopolitan in their eating habits – specialising in grain or fruit, but also eating other food as it becomes available. Rodents and most primates fit this category – they eat a variety of things. Most primates in particular will eat leaves, fruit, insects, lizards, birds, small mammals - pretty much anything they can get hold of. They are pretty typical omnivores, with a diet that varies depending on what is available to them. Rodents are similar, with squirrels eating insects, bird eggs and chicks if they can get them, bark when food is short.

Obligate carnivores (cats, hyaenas, otters, stoats, etc.) are at the other end of the spectrum to the ruminants. They need meat (including invertebrates) and are not physiologically equipped to eat anything else. Most members of the group Carnivora actually display a range of omnivory, so wolves, badgers, bears, etc. will also eat fruit, tubers, flowers etc.

Humans have distant ancestry amongst frugivores, but they lost the arboreality needed to access fruit on trees whilst developing bipedalism. Selective pressures must have been favouring the acquisition of resources on the ground for some reason (there are many possibilities that it is not worth going into here). Given that our close relatives Pan troglodytes are known to regularly forage for insects (using tools) and even hunt monkeys, there is a good chance that our lineage has been eating some meat since before we split with the Pan branch. There are many theories about the selective forces that have shaped humanity and they are difficult to prove, but there is evidence to suggest that part of the reason humans became bipedal and able to communicate so well was linked to scavenging and/or hunting. The fact that from 2.5 million years ago stone tools have been found with shapes suggestive of a function in butchery provides some solid indications of meat eating and by 1.8 million years ago there is direct evidence of butchery on mammoth bones from Olduvai Gorge.

Throughout the ice age it is likely that Hominids only managed to survive on their northern fringes by eating meat (similar to modern Inuit), since the vegetation would not be suitable for consumption by anything other than specialised herbivores. Eating meat may be an inefficient use of land, but it is an efficient way to utilise land that is unsuitable for producing food edible by humans. Grass is the key, since it grows from its base rather than its tip (as other plants do), so it can be harvested repeatedly. It is also very tolerant to drought or flooding and it can grow in very shallow soil. However, it is inedible to humans, except as a grain (and even then natural grains are nutritionally poor in terms of the energy yield for the processing required).

Humans began domestication of animals 15,000 years ago with the dog – a useful hunting partnership. Sheep and cats were domesticated 10,500 years ago followed by goats, pigs and cattle by 9,000 years ago. In the subsequent 9,000 years selective breeding has led to animals which have much greater fat content, produce more milk and are far more docile than their wild counterparts. Plants began being domesticated from ~10,500 years ago (perhaps the cats were domesticated to deal with pests of stored grains) and it is with the domestication of plants that grain sizes were increased to the point of being nutritionally significant. In many ways humans are better adapted to eating meat than to eating grains, since our lineage has had longer (a minimum of 2.5 million years) to evolve the required enzymes, hence the relatively high proportion of people who are intolerant or allergic to wheat and gluten – since we’re still not well adapted to eating grain as a species having only had it on the menu in significant amounts for 10,000 years.

As an interesting aside, pandas have evolved from a Carnivore ancestor through omnivory and to herbivory. They are very inefficient at digesting their bamboo diet, but they have adaptations that make them dependent upon this low nutrient food. However, pandas still eat meat when they are able to get it (I'm not sure if they consider this a lapse or a treat).

_________________
Ask a biologist
My blog


October 7th, 2008, 4:34 pm
Profile WWW
User avatar

Joined: February 27th, 2008, 1:17 pm
Posts: 2976
Location: Greater London
Paolo wrote:
Gorillas are big, they eat almost constantly (as a result they have impressive buttressing of the skull to cope with the forces involved in all that chewing) and they tend to engage in little unnecessary activity.
:nod:


October 7th, 2008, 5:10 pm
Profile
User avatar

Joined: September 13th, 2008, 9:15 am
Posts: 1474
Location: Forest Hill, London
:smile:

_________________
Ask a biologist
My blog


October 7th, 2008, 5:26 pm
Profile WWW
User avatar

Joined: August 30th, 2008, 3:31 pm
Posts: 66
It should be emphasized that humans are omnivores, by definition, simply because that is what they do as a species. Humans are not omnivores in the sense that they need to eat both "carne" and "herb." We are just fine, nutritionally, eating only plant foods.

Individuals have a choice between eating a vegetable based diet with some animal foods and a diet of exclusively plant foods. Eating a meat based diet is not a nutritionally sound option. Eating a meat only diet is simply out of the question.

So I think that the point about humans being omnivores is entirely misleading when introduced to the debate over whether we should or shouldn't eat animals. I am a member of a species that is omnivorous, but as an individual I am an herbivore. Those are both facts. Just look at our diets.

Of course, it is much more to the point to consider whether one can eat a diet without any animal foods and whether or not one should eat animal foods than to discuss whether or not many people do so. It is entirely misleading to think that just because many people can and do eat animals that we are supposed to, as part of some sort of naturalistic fallacy.


October 7th, 2008, 6:45 pm
Profile
User avatar

Joined: September 13th, 2008, 9:15 am
Posts: 1474
Location: Forest Hill, London
erasmusinfinity wrote:
Eating a meat based diet is not a nutritionally sound option. Eating a meat only diet is simply out of the question.

I disagree. The Inuit have lived on a meat-based diet for the last 1000 years and it is likely that earlier cultures in ice-bound environments have done the same. Anthropologists living with the Inuit have adapted to even the winter diet (which is almost entirely meat) with no ill effect. Offal provides the majority of vitamins that plants provide in our diet - it is interesting to note that the dietary problems with a meat only diet in our society are largely due to our fixation on eating just the muscle and eschewing the offal.

Humans are perfectly capable of being almost exclusively carnivorous, as long as they get the right balance of body parts from the right animals - much the same as being able to get everything we need from the right balance of parts from the right plants.

_________________
Ask a biologist
My blog


October 7th, 2008, 7:07 pm
Profile WWW
User avatar

Joined: August 30th, 2008, 3:31 pm
Posts: 66
http://www.diseaseproof.com/archives/di ... onger.html

Quote:
Inuit Greenlanders, who historically have had limited access to fruits and vegetables, have the worst longevity statistics in North America. Research from the past and present shows that they die on the average about 10 years younger and have a higher rate of cancer than the overall Canadian population.1

Similar statistics are available for the high meat-consuming Maasai in Kenya. They eat a diet high in wild hunted meats and have the worst life expectancy in the modern world. Life expectancy is 45 years for women and 42 years for men. African researchers report that, historically, Maasai rarely lived beyond age 60. Adult mortality figures on the Kenyan Maasai show that they have a 50% chance of dying before the age of 59.2

We now know that greatly increasing the consumption of vegetables, legumes, fruits, and raw nuts and seeds (and greatly decreasing the consumption of animal products) offers profound increased longevity potential, due in large part to broad symphony of life-extending phytochemical nutrients that a vegetable-based diet contains. By taking advantage of the year-round availability of high-quality plant foods, we have a unique opportunity to live both healthier and longer than ever before in human history.


October 7th, 2008, 8:23 pm
Profile
User avatar

Joined: September 13th, 2008, 9:15 am
Posts: 1474
Location: Forest Hill, London
erasmusinfinity wrote:
Quote:
Inuit Greenlanders, who historically have had limited access to fruits and vegetables, have the worst longevity statistics in North America. Research from the past and present shows that they die on the average about 10 years younger and have a higher rate of cancer than the overall Canadian population.1

Similar statistics are available for the high meat-consuming Maasai in Kenya. They eat a diet high in wild hunted meats and have the worst life expectancy in the modern world. Life expectancy is 45 years for women and 42 years for men. African researchers report that, historically, Maasai rarely lived beyond age 60. Adult mortality figures on the Kenyan Maasai show that they have a 50% chance of dying before the age of 59.2

That article provides a wonderful example of how to twist statistics to say what you want!

For starters both the Inuit and Maasai have small populations with low outbreeding, immediately increasing the risk of a host of diseases (including cancer). More importantly perhaps, they both still hunt actively for their dietry needs, which is a high-risk mode of life. Another factor is that both live in marginal environments that have avoided being heavily populated because they are so inhospitable. Don't expect high life expectancy when you live in a place with limited water or intensely cold conditions.

It is interesting that the article gives life expectancy for the Maasai (incorrectly stating that "have the worst life expectancy in the modern world" at an average age of 43.5 years for the population, when Zambia, Zimbabwe, Angola, Sierra Leone and Afghanistan all have life expectancy below 42.2 years), but it just provides a relative value for the Inuit, which is 64.2 years by the way. Here is an article that looks at Inuit life expectancy without a bias against meat: http://www.statcan.ca/Daily/English/080123/d080123d.htm
It is interesting to note that the main suggested rationale is socio-economic.
Quote:
Analysis of the 2001 Census data revealed lower levels of education and income and poorer housing conditions for the Inuit-inhabited areas compared with Canada as a whole. Any or all of these, in addition to lifestyle risk factors and environmental conditions, could be at least partly responsible for the lower life expectancy in those areas.


I can play with statistics too. I downloaded the available data for the world consumption of meat per capita per country (figures for 2002, source Food and Agriculture Organization of the United Nations (FAO), FAOSTAT on-line statistical service (FAO, Rome, 2004). Available online at: http://apps.fao.org.) and the average life expectancy at birth by country (figures for 2000-2005, source Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat, 2007. World Population Prospects: The 2006 Revision. Dataset on CD-ROM. New York: United Nations. Available on-line at http://www.un.org/esa/population/ordering.htm), which I then plotted on a simple scatterplot through which I plotted a regression line. The correlation coefficient that was generated was y = 0.1978x + 57.962, where y=average life expectancy at birth and x=per capita meat consumption in kg. You notice that this is a positive correlation?

These data allow me to honestly say that there is a positive correlation between the amount of meat eaten and increased life expectancy. These data include 173 countries and I have not added any interpretation of my own - they are considerably more interesting that the two data points and anecdotal evidence used in the article you cited, but when I add my interpretation I would dismiss the correlation because the analysis has not been controlled against other factors such as war, civil unrest and poverty.

I'm all in favour of using data to support an argument, but please make sure the data are a) accurate and b) unbiased, otherwise it's just propaganda and I for one will not let that pass.


Attachments:
meatvslifeexp.gif
meatvslifeexp.gif [ 6.53 KiB | Viewed 2448 times ]

_________________
Ask a biologist
My blog
October 8th, 2008, 11:22 am
Profile WWW
Display posts from previous:  Sort by  
Reply to topic   [ 43 posts ]  Go to page 1, 2, 3  Next

Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group
Designed by ST Software for PTF.