# Is man a meat-eater or a vegetarian by nature? **URL:** \ **Category:** Great Debates\ **Created:** [January 13, 2012, 11:12am UTC](https://boards.straightdope.com/t/is-man-a-meat-eater-or-a-vegetarian-by-nature/609381 "2012-01-13T11:12:03Z")\ **Posts on this page:** 9\ **Page:** 13
**Author:** ![New\_Deal\_Democrat](https://avatars.discourse-cdn.com/v4/letter/n/9d8465/32.png) [@New\_Deal\_Democrat](https://boards.straightdope.com/u/New_Deal_Democrat)\ **Post date:** [February 8, 2012, 11:32pm UTC](https://boards.straightdope.com/t/is-man-a-meat-eater-or-a-vegetarian-by-nature/609381/241 "2012-02-08T23:32:59Z")
By nature the human species is omnivorous. Distinctively human evolution began about six million years ago when the Rift Valley in eastern Africa divided the common ancestor of humans and Chimpanzees. After the split meat became important to the proto human diet, and hunting became important to human evolution. Even during the paleolithic era meat was supplemented with plant foods. With the beginning of agriculture in the Mid East some ten thousand years ago, grains and beans became important to the human diet. Nevertheless, it took several thousand years of evolution for humans to easily process the higher carbohydrate diet that a largely plant diet provided. Populations that more recently adopted an agricultural diet, such as North American Indians, and Australian Aborigines are more vulnerable to type 2 diabetes. One can live on an all plant diet if one mixes grains and beans to get complete protein, and if one takes vitamin B 12 supplements. Vitamin B 12 is the one nutrient not found in plant foods. ---
**Author:** ![robinson](https://avatars.discourse-cdn.com/v4/letter/r/848f3c/32.png) [@robinson](https://boards.straightdope.com/u/robinson)\ **Post date:** [February 17, 2012, 7:07am UTC](https://boards.straightdope.com/t/is-man-a-meat-eater-or-a-vegetarian-by-nature/609381/242 "2012-02-17T07:07:51Z")
The question demands an affirmative answer. ---
**Author:** ![aaaa](https://avatars.discourse-cdn.com/v4/letter/a/eb8c5e/32.png) [@aaaa](https://boards.straightdope.com/u/aaaa)\ **Post date:** [February 17, 2012, 7:12am UTC](https://boards.straightdope.com/t/is-man-a-meat-eater-or-a-vegetarian-by-nature/609381/243 "2012-02-17T07:12:21Z")
Can’t humans only get Vitamin B12 from eating meat or other animal products? ---
**Author:** ![Odesio](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/odesio/32/20003_2.png) [@Odesio](https://boards.straightdope.com/u/Odesio)\ **Post date:** [February 17, 2012, 8:04am UTC](https://boards.straightdope.com/t/is-man-a-meat-eater-or-a-vegetarian-by-nature/609381/244 "2012-02-17T08:04:36Z")
> [@aaaa](#): > > Can’t humans only get Vitamin B12 from eating meat or other animal products? > **[Vitamin B12](https://www.vegansociety.com/resources/nutrition-and-health/nutrients/vitamin-b12)** > > Vitamin B12 is needed to help speed up chemical reactions in our bodies. Yup. According to the Vegan Society, there is no reliable natural source of B12 to be found in a vegan diet. They encourage vegans to eat foods fortified with B12. The need for B12 is what really refutes the argument that human beings were meant to be vegetarian. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 17, 2012, 8:15am UTC](https://boards.straightdope.com/t/is-man-a-meat-eater-or-a-vegetarian-by-nature/609381/245 "2012-02-17T08:15:27Z")
> [@Odesio](#): > > [http://www.vegansociety.com/lifestyle/nutrition/b12.aspx](http://www.vegansociety.com/lifestyle/nutrition/b12.aspx) > > Yup. According to the Vegan Society, there is no reliable natural source of B12 to be found in a vegan diet. They encourage vegans to eat foods fortified with B12. The need for B12 is what really refutes the argument that human beings were meant to be vegetarian. You’re right, however, in practice, there’s also no such thing as a natural, reliably-vegan diet - staple foods such as grains and pulses tend to contain insect remains (especially once the presence of the insect remains has been obscured by processing - and it’s exceptionally hard to prevent this). And insects happen to be quite a good source of vitamin B12. ---
**Author:** ![DrFidelius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drfidelius/32/3447_2.png) [@DrFidelius](https://boards.straightdope.com/u/DrFidelius)\ **Post date:** [February 17, 2012, 12:21pm UTC](https://boards.straightdope.com/t/is-man-a-meat-eater-or-a-vegetarian-by-nature/609381/246 "2012-02-17T12:21:37Z")
How much insect material is needed to supply an adult’s B12 needs? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 17, 2012, 1:51pm UTC](https://boards.straightdope.com/t/is-man-a-meat-eater-or-a-vegetarian-by-nature/609381/247 "2012-02-17T13:51:19Z")
According to [this](http://www.organicvaluerecovery.com/studies/studies_nutrient_content_of_insects.htm) page, mealworm larvae contain 12.3 micrograms of B12 per kg of insects. Adult human RDA for B12 bottoms out at 0.3 micrograms, so you’d have to eat about 25g (~an ounce) of mealworms to get this - which seems like quite a lot to eat by accident. However, I think I’m right in saying that the B12 in insects is produced by their gut flora and that their droppings also contain the vitamin - and probably more concentrated than in the insect bodies, so maybe it’s as little as 5 or 10 grams of mealworm poo that you need in your daily loaf of bread. On reflection, it seems like you might obtain enough of the nutrient to stave off serious malnutrition, but not enough to thrive. ---
**Author:** ![Michael63129](https://avatars.discourse-cdn.com/v4/letter/m/3da27b/32.png) [@Michael63129](https://boards.straightdope.com/u/Michael63129)\ **Post date:** [February 17, 2012, 5:04pm UTC](https://boards.straightdope.com/t/is-man-a-meat-eater-or-a-vegetarian-by-nature/609381/248 "2012-02-17T17:04:27Z")
Besides B-12, another nutrient to consider is [omega-3 fatty acids](http://en.wikipedia.org/wiki/Omega-3_fatty_acid), and while they can be obtained from plants (mainly nuts and seeds), they are in a form (ALA) that must be converted by your body into more useful forms (DHA and EPA), which it does very inefficiently, especially in men: > [@](#): > > N-3 fatty acids have many health benefits and are considered essential fatty acids, meaning that they cannot be synthesized by the human body but are vital for normal metabolism. > > Conversion efficiency of ALA to EPA and DHA > The short-chain n−3 fatty acids are converted to long-chain forms (EPA, DHA) with an efficiency below 5%[13][14] in men, and at a greater percentage in women which may be due to the importance for meeting the demands of the fetus and neonate for DHA.[ > > The 18 carbon α-linolenic acid (ALA) has not been shown to have the same cardiovascular benefits that DHA or EPA may have.[31] Currently, there are many products on the market that claim to contain health-promoting “omega 3”, but contain only ALA, not EPA or DHA. These products contain mainly plant oils and must be converted by the body to create DHA. DHA and EPA are made by marine microalgae. These are then consumed by fish and accumulate to high levels in their internal organs. Also, while not necessarily related to a meat/plant diet, the high omega-6 content typical of many grains (the average Western diet has a 6:3 ratio as high as 30:1) has been thought to contribute to heart disease and other disorders: > [@](#): > > [Negative health effects](http://en.wikipedia.org/wiki/Omega-6_fatty_acid#Negative_health_effects) > > Modern Western diets typically have ratios of n−6 to n−3 in excess of 10 to 1, some as high as 30 to 1. The optimal ratio is thought to be 4 to 1 or lower. > > Excess n−6 fats interfere with the health benefits of n−3 fats, in part because they compete for the same rate-limiting enzymes. A high proportion of n−6 to n−3 fat in the diet shifts the physiological state in the tissues toward the pathogenesis of many diseases: prothrombotic, proinflammatory and proconstrictive.[8] > > Chronic excessive production of n−6 eicosanoids is associated with heart attacks, thrombotic stroke, arrhythmia, arthritis, osteoporosis, inflammation, mood disorders, obesity, and cancer. This also applies to most meat consumed today; grain-fed beef has a much higher omega-6 content than grass-fed beef (and is also much worse environmentally and uses up food crops that could feed many more people): > [@](#): > > In a 2009 study which was a joint effort between the USDA and researchers at Clemson University in South Carolina grass-fed beef was compared with grain-fed beef and researchers found that grass-fed beef is: lower in total fat, higher in beta-carotene, higher in vitamin E (alpha-tocopherol), higher in the B-vitamins thiamin and riboflavin, higher in the minerals calcium, magnesium, and potassium, higher in total omega-3s, higher in CLA (cis-9 trans-11) which is a potential cancer fighter, higher in vaccenic acid (which can be transformed into CLA), lower in the saturated fats linked with heart disease, and has a healthier ratio of omega-6 to omega-3 fatty acids (1.65 vs 4.84). ---
**Author:** ![James\_Polichak](https://avatars.discourse-cdn.com/v4/letter/j/a698b9/32.png) [@James\_Polichak](https://boards.straightdope.com/u/James_Polichak)\ **Post date:** [February 18, 2012, 9:40am UTC](https://boards.straightdope.com/t/is-man-a-meat-eater-or-a-vegetarian-by-nature/609381/249 "2012-02-18T09:40:15Z")
Behold what havok I have unleashed by providing a simple piece of evidence that relates to a complex evolutionary process! False attributions of “oughts”! g8 consternation re abbr! luring both anti-grain and anti-meat posses into an epic brawl! AND TOO MANY EXCLAMATION POINTS USED HERE RIGHT NOW!!! For my final bunker-buster, deal with this: awl my base r blng ta da lil kittehs who wants 2 haz cheezeburger! [Previous page](https://boards.straightdope.com/t/is-man-a-meat-eater-or-a-vegetarian-by-nature/609381.md?page=12)