Author Topic: Are humans natural carnivores?  (Read 9539 times)

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Offline Satya

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Are humans natural carnivores?
« on: March 18, 2010, 07:24:02 PM »
Certainly we have a digestive system like carnivores do.  Our teeth look more like omnivore teeth, but that fails to take into account the fact that we use tools like knives, and as such, have little selective pressure to grow longer fangs.  (That said, molar number 3 for me is rather fanglike).

What other arguments can you think of to support the idea that humans are natural carnivores?

Offline paleo donk

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Re: Are humans natural carnivores?
« Reply #1 on: March 18, 2010, 08:07:48 PM »
Barry Groves has a good article here - http://www.second-opinions.co.uk/carn_herb_comparison.html

The only differences seem to be that humans have an appendix and amylase in the saliva to digest starch whereas carnivore do not .

We can both digest carbohydrates well enough though once they have been released from their cell walls. Cats and dogs stay alive and function well on high carb diets.
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Offline William

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Re: Are humans natural carnivores?
« Reply #2 on: March 18, 2010, 08:32:46 PM »
Negative proof is that we live such miserably short & sickly lives.
From biology, mammals live 7 times their age of physical maturity, which for us is 32. That's in laboratory conditions, I would assume, where they can't get ice cream, chocolate, bacon etc.

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Offline Marnee

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Re: Are humans natural carnivores?
« Reply #3 on: March 18, 2010, 10:17:11 PM »
We don't convert fiber into fat like herbivores (gorillas) or even omnivores like bears.  And metabolically we require a lot of fat, especially due to our very large brains, so we have to get it from somewhere, because we aint getting it from plants.

Also, aren't our bodies structured like predators?  We are small, agile, and fast.  We have eyes in the front for good depth perception.  And our ears are good for precisely locating things by sound.  

Being smart we can overcome physical disadvantage by cleverness.  You don't need cleverness to compete for plants and propagate the species, especially if you are a herd animal.  However, amongst predators, I can see cleverness as a big competitive advantage.  Cat and dog owners can observe this cleverness and learning ability in their little predators.  Predatory birds also often exhibit greater cleverness than other birds.
« Last Edit: March 18, 2010, 10:26:19 PM by Marnee »

Offline Paleoeat

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Re: Are humans natural carnivores?
« Reply #4 on: March 19, 2010, 12:09:08 AM »
we must remember that we evolved from herbivorous apes, this may be why our teeth are not like a true carnivores.  but they do have  pointed cusp and triangular ridges that are more slicing than crushing.  herbivores have teeth that are flat and constantly growing due to wear by plant matter.  our teeth do not continuously growe and have thick enamel lie a carnivore.  the incisors are  flat like a cats.

the salivary amylase stumps me,  but it may be vestigial like our apnedix?????

I believe there is a bone isotope study of Neanderthals and humans (oldet than 10,000 yeras that show htem to be top level carnivores.  anyone have a link?
« Last Edit: March 19, 2010, 12:12:45 AM by Paleoeat »
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Offline Satya

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Re: Are humans natural carnivores?
« Reply #5 on: March 19, 2010, 05:48:07 PM »
I am so glad I asked this question.  You guys are coming up with answers I would not have considered.  And keep those ideas coming!

Paleo donk, I would say domestic cats and dogs can survive on high carb.  But function highly?  Not really.  The cat and dog chow just makes them overeat and get the same diseases humans do on highly processed carbs.  Since I switched my animals to raw meat, they behave much differently.  The cats eat some cooked meat too, as they are not as into it as the dog and chickens are.

Offline William

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Re: Are humans natural carnivores?
« Reply #6 on: March 19, 2010, 08:41:08 PM »


I believe there is a bone isotope study of Neanderthals and humans (oldet than 10,000 yeras that show htem to be top level carnivores.  anyone have a link?

No link, but as I recall, the bone composition proved to be identical to that of modern wild African lions.

Offline lex_rooker

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Re: Are humans natural carnivores?
« Reply #7 on: March 21, 2010, 10:52:24 AM »
Negative proof is that we live such miserably short & sickly lives.

I suppose this depends on your point of view.  Most animals in the wild have a very short average lifespan regardless of their maximum life span due to environmental conditions - like drought, disease, or being eaten by another animal.  I believe I've read where the average lifespan of humans in paleo times was less than 30 years.  Today, even with a less than optimal diet, most of us live in comparatively good health well into our 70s or 80s.

From biology, mammals live 7 times their age of physical maturity, which for us is 32.

This seems a bit of a stretch.  Biological maturity is usually defined as that point where the animal is capable of reproduction.  For humans this would be at the completion of puberty.  If we are conservative and set the completion of puberty at around 15 - 16 (even though many are fully capable of reproduction earlier than that) then our expected maximum lifespan would be around 105 - 112.  This seems to fit very well with actual experience.  Occasionally there is an outlier that lives beyond this age range but for the most part this seems to be the maximum average age we can achieve.

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Offline William

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Re: Are humans natural carnivores?
« Reply #8 on: March 21, 2010, 01:41:13 PM »
 I believe I've read where the average lifespan of humans in paleo times was less than 30 years.

I'm surprised that you would mention that canard. It's used by trolls such as Geoffrey.

Quote
 Biological maturity is usually defined as that point where the animal is capable of reproduction.  

Biological maturity is the end of physical growth.

Offline Spidey

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Re: Are humans natural carnivores?
« Reply #9 on: March 21, 2010, 01:45:01 PM »

I'm surprised that you would mention that canard. It's used by trolls such as Geoffrey.


Let's avoid calling names please and keep to the subject at hand.  Thank you.
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Offline Satya

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Re: Are humans natural carnivores?
« Reply #10 on: March 21, 2010, 03:55:59 PM »
 Biological maturity is usually defined as that point where the animal is capable of reproduction.  


Biological maturity is the end of physical growth.


Perhaps there is a difference between sexual maturity and biological maturity?  I don't know, but here's a link that discusses both terms.  Perhaps they are using the terms interchangeably?

William, anyone gaining weight might be considered still growing. :laugh:  What do you mean by physical growth?

http://informahealthcare.com/doi/abs/10.1080/030144600282389
Quote
It is widely considered that biological maturity influences physical fitness test performance, children can be advantaged/disadvantaged in physical fitness tests by being more or less mature than counterparts of the same chronological age. The current study sought to investigate the effect sexual maturity had upon performance in physical fitness tests. A cross-sectional study involving 161 girls and 152 boys was carried out. Each subject was assessed for stature, mass, self-assessment of sexual maturity, vertical jump, hand grip strength and the 20 m shuttle run test, all procedures were standardized. Spearman's rank correlation coefficients were developed to assess the relationship between maturity and physical fitness measures. ANCOVA inferential statistics were performed to investigate if performance in physical fitness tests differed between children of different sexual maturity stages irrespective of mass and stature. Significance was set at p < 0:05. Stage of sexual maturity was significantly correlated with all physical fitness measures (boys: r = 0.56 to 0.73; girls: r = 0.24 to 0.46). ANCOVA revealed that when stature and mass were taken into account significant differences were evident between sexual maturity stages in boys but not girls. This suggests that increases in mass and stature are primarily responsible for variation in girls' physical performance throughout maturation, whereas in boys there are some qualitative differences in performance due to other factors. It was concluded that sexual maturity has a large influence on physical fitness measures in boys but less effect in girls. Rating of physical fitness, particularly for boys should take into account biological maturity.


Emphasis mine.
« Last Edit: March 21, 2010, 04:05:37 PM by Satya »

Offline William

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Re: Are humans natural carnivores?
« Reply #11 on: March 21, 2010, 04:54:54 PM »
My reference for growth is from paleoman's bones compared to ours.
The last growth is a hard coating on the ends of bones for both, then it's just maintenance which on a SAD diet kills us.
Hypothetically, if we find a perfect diet and avoid all pollution, we would not age and would live forever.

 The difference is that our bones show so many marks of disease that age-at-death can be reliably estimated, while paleo bones show no such disease marks at all, so that's why some have said that they all died at 32. Or whatever.
This misses the point of why we eat paleo - so as not to be diseased anymore, and it works as well as may be in a polluted earth.

This is assuming that the bones of those younger than 32 (age of physical maturity) show no signs of disease in our time or in the paleolithic, and this assume a perfectly functioning immune system, which would have to be supported by a perfect diet, necessarily raw so as to support enzyme production.

Offline Erasmus

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Re: Are humans natural carnivores?
« Reply #12 on: March 22, 2010, 11:45:54 AM »
Are people still trotting out average lifespan as if to show how long people lived?  Crazy.  Until the lifespan numbers approach genetic maximums average lifespan is just an indirect measurement of infant mortality and to a lesser extent hazardous living conditions.

In the US, per average lifespan, women live longer than men.  Everybody knows this.  Here is what most people don't know.  Per the actuarial charts (the ones I looked at 15 years ago), of people that are alive at 60, men are expected to live about 1 year longer.  But everyone knows women live longer than men, right?  Average lifespan is meaningless number and generally a lie even when it tells the truth.

-E

Offline lex_rooker

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Re: Are humans natural carnivores?
« Reply #13 on: March 22, 2010, 01:05:20 PM »

Offline runningdog

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Re: Are humans natural carnivores?
« Reply #14 on: March 22, 2010, 02:40:56 PM »
Negative proof is that we live such miserably short & sickly lives.
From biology, mammals live 7 times their age of physical maturity, which for us is 32. That's in laboratory conditions, I would assume, where they can't get ice cream, chocolate, bacon etc.


You should talk to Kwasniewski. He claims that with perfect diet (and after few generations on perfect diet) humans can live up to 1000 years.
Since we are the first generation 150 seems like a good shot.