What do animals eat? (And how does this relate to an optimal human diet?)

(Geoffrey) #61

I have experienced some of the same behavior in hamsters I used to raise.

(Geoffrey) #62

Good point but are those milks the same? I don’t know. If so, were they milked for human consumption? I’ve heard of children that couldn’t tolerate cows milk but did just fine on goat milk. I raise sheep and and sometimes I’ll have a goat around but I’ve never milked them.

I don’t know and I’ve never heard of any kind of study to look into it.

I’ve only raised a few rabbits in my time and my domesticated rabbits rarely ate the carrots themselves but instead they preferred the leafy tops. I do know that domestic rabbits taste much better than wild rabbits even though both are good.

I suppose that could be the case. Deer love persimmons, berries, watermelon, apples and so on. Bears love anything sweet when it comes to fruit. Wild hogs absolutely go ape over any kind of fruit but then again hogs will eat anything including each other. Coyotes will eat fruit as well because they are opportunistic. Birds of course eat berries and fruit. Bats as well. Chickens love fruit as well as vegetables and meat. Ours love their grapes. The list goes on and on as there are many more animals that eat fruit. So do they have a specialized gut? I haven’t a clue. That a pretty diverse list I just noted, all with different species specific diets and yet they all indulge I’d eating fruit. But hey, I’m not a wildlife biologist. I’m just a hack that’s had a small farm and hunted most of my life.

(Bacon is a many-splendoured thing) #63

Technically, a “vegetable” is any part of the plant that is not a fruit or a seed, commonly leaves, stalks, or tubers.

In common parlance, “fruit” implies sweetness, and savoury fruits are considered “vegetables.” This includes, but is not limited to tomatoes, cucumbers, all gourds–they are all fruits, but colloquially and commercially, they are vegetables, because they are not sweet.

Nuts are fruits, as well, but they are considered to be in their own category.

(KM) #64

One important consideration here is that the society probably has to be agricultural or at least pastoralist. I would think it very unlikely to find a society that would / could chase down wild animals with young to milk them. Assuming this is true, we would not have evolved to drink milk beyond that of humans. Not sure that puts ruminant milk off the table, but it does put it outside the category of a natural human food.

(Edith) #65

It seems a lot of different types of animals eat fruit: mammals, birds, fish, reptiles (guessing on this, but wouldn’t be surprised). Maybe fruit is in a special category of digestibility. They are lowish in fiber and other plant toxins, thus allowing digestion in many different types of digestive tracts.

Some fruits tend to be higher in oxalate, such as berries, but I’m will to bet that is because of the seeds. You can’t eat berries without eating the seeds. Since the seeds of berries most likely pass through the body undigested, maybe the oxalates in berries don’t matter that much. Again, making them more digestible and less toxic to a wide variety of species.


Wow Im learning so much from peoples comments and the research it is provoking me to do to respond. I never really expected to learn so much and get so many answers to my questions. Thanks everybody.


To address the question, do animals eat vegetables, fruit and berries?
Lots of people are presenting evidence of animals eating these foods. Many of these however have the following issues:

  1. Human intervention - ie from gardens or agriculture.
  2. It only constitutes a small part of their diet i.e. omnivores.
  3. Only a very few specific types of the species possess the ability to eat them exclusively eg fruit bats

What I would like to find are animals that fit the following criteria:

  1. They eat vegetables, fruit or berries in the wild.
  2. It constitutes a large part of their diet, 30% or more.
  3. Ideally widespread throughout the species (but the specialised ones are also interesting).

Good luck everyone.


Thanks for you post Edith. See my post below for more on the fruit and vegetables question.


Thanks Paul, that’s a very good explanation of the definition of what a vegetables is for the purposes of this discussion.


Thats exactly what I was thinking KM.
Milk and dairy consumption has become one of the most interesting subjects, and your comment prompted me to do some more research and I found this article:

The craziest thing in this article is that it is thought we have only been drinking milk for 6,000 years! I really would have thought that dairy consumption would have predated cereal crop agriculture which is supposed to have happened around 12,000 years ago.

Just found another article that pushes the date back to 9,000 years ago.


Hi Geoffrey, thanks for your insightful comments as always. Its great to hear someone with so much “real world” experience with animals. Mine unfortunately is very limited, apart from the aquatic world as I’m a scuba instructor. One of the reasons I started this thread was to learn from people with real experience due to my lack of knowledge, so thank you.
Please see my post below for more on the fruit and vegetables question.
And as for the milk question Im going to post a thesis about it later.

(KM) #72

That is surprising. Perhaps it’s because early pastoralists were much more concerned with keeping the baby animals alive. It probably took a bit of a leap to envision drinking from an animal if you think about it, and in harsh conditions the babies probably needed all the milk they could get in any event. I wonder if animal milk was occasionally considered as a last resort.

(Edith) #73

Turns out there are a lot of animals in the wild that have fruit as a large percentage of their diets.


(Bacon is a many-splendoured thing) #74

Question: does grass count as a vegetable?


Bears eat fruits and berries, especially when they need to fatten up for the winter. That accounts for a large part of their diet, at least seasonally.

Rabbits and deer eat lettuce and other garden crops. Deer are ruminants, so they eat plants year-round, for sure. (And remember that elk and moose are deer species, as well.)


That’s a fantastic reply. Thanks so much Edith. Don’t know why I was having so much trouble finding this evidence - probably due to looking at so many different food groups and animals!
Interesting excerpts from your articles:

“20% of known mammal species are frugivorous animals. This type of diet is very significant and important among various animals.”

“Animals that eat fruit as a primary source of food are called frugivores. However, many of these animals do not subsist solely on fruit; they also supplement their diet with other plant materials like roots, leaves, and flowers.
They are considered frugivorous under two conditions: If their diet is more than 50% fruit-based, and also if their feeding habits release seeds that can germinate and grow.
Additionally, when it comes to diets in the animal kingdom, many species of herbivores and omnivores eat fruit, depending on its availability. As a result, more often than not, fruit consumption is largely determined by the season of the year.
For these species, in particular, fruit does not consist of the larger percentage of their diet, as their primary sources of nutrition are acquired from other plants or animals.”

So to use our scoring system there are animals that would score 3 points (Animals that eat the food as the majority of their diet (80% and over)). However it seems to me that these animals are highly specialised and the exception rather than the rule.
A large number of animals would score 2 points (Animals that eat the food as a large part of their diet (40% or so)). These animals eat a lot of fruit but need to supplement their diet with other foods. This is possibly due to lack of fruit during certain seasons or maybe also for nutrient diversity reasons?
A large number of animals, the omnivores, would score 1 point (Animals that eat the food as a small part of their diet (10% or so)).

So now that we have the answer about animals and fruit, the question is what category do humans fit in?
I think it’s clear that we don’t fit into the 3 point category. I don’t believe humans have that kind of specialisation.
Monkeys, our closest relatives, are in the 2 point category. Tree leaves also form a large part of a monkey’s diet but humans have lost that ability. Do we still have the ability to eat fruit, or have we also lost that?
I would guess humans are most likely in the 1 point omnivore category. Most tribal humans as far as I know eat very little fruit, but some of them do occasionally. It seems from the Masai and Inuit that it certainly isn’t a critical part of a human diet.

So can fruit be part of an optimal human diet? I think the mostly likely answer would be yes it can, but only in a very small amount when seasonally available. And it seems certainly not to be a necessary part of an optimal human diet.

I would guess the above also probably also applies to berries, unless anyone has some other ideas?


Thanks Paul, no for this discussion Im keeping grass in its own category. We know that many herbivores eat mostly grass and that we cant do so because we don’t have the stomachs or enzymes to digest it. Since we do eat vegetables I wanted to try a find out if any animals eat them (or at least their non-hybridised versions) in the wild. So I separated the categories to try to tease out this information.

(Bacon is a many-splendoured thing) #77

Or the stomach bacteria, either.


I have read just a bit, how busy this thread got, I need to come back later!

How much is that because 3kg definitely doesn’t cut it for my family members and I would worry about all the fructose and sugar in general way, way more.
And 3kg sounds pretty normal in watermelon season, surely many people eat it galore, why would a small family buy a huge one then? It doesn’t last long.
For very long term I only ate a bit above 1kg fruit a day, that’s little (okay, not from my current viewpoint :smiley: ) but even I didn’t want much more than that.
Fruit is Nature’s candy so I don’t call it optimal either in big amounts. Maybe the least sweet ones.

That would be nice as I read and watch animal infos a lot but don’t retain everything and there may be mistakes here and there, sometimes the details aren’t enough… I just can’t resist writing here as I always was excited about animals and wondering about things, nutrition is interesting too and useful to know more about it… So yes, I just bring out things from my memory banks but I can’t say they must be right. But I remember pandas don’t have it optimal, their babies grow slowly too, getting enough energy isn’t easy for them… It’s probably the best they can do in their habitat though. Evolution is merciless. Though it has some weird VERY suboptimal, useless, harmful things that managed not to kill the species so it was “good enough” for evolution. Evolution doesn’t make things better and better, living beings just happens to mutate somewhere and if it doesn’t kill them and some other mutation isn’t even much better, it’s good enough.

Humans are opportunistic eaters (historically, at least, not necessarily the ones who have plenty of options in modern times). They drank cow milk, goat milk, camel milk, horse milk if only that was the available animal… Goat and sheep is pretty normal, there is sheep quark in the supermarkets here, that’s quite common. Goat dairy is less so, I only get it from houses (a supermarket had it once but I couldn’t get any), farms sell it too.


Hi Shinita, thanks for your comments and continued interest in this thread. Very interesting about your family and fruit quantity consumption. My family were never big fruit eaters so it’s very interesting to see how much can be eaten without ill effects (at least any that are easily noticeable like diarrhoea).

Also really interesting about the baby Pandas. I had always assumed that without human or climatic intervention (winter, droughts etc) that animals would naturally eat an optimal diet. From what you say Pandas at least have evolved to eat a sub optimal diet. Very interesting. Does anyone else know of any other in this category ie animals that have evolved to eat a sub optimal food for the majority of their diet in their natural habitat under normal conditions ie outside of climatically difficult times (winter, drought etc).

(Geoffrey) #80

Koala bears maybe? But is it really sub optimal if that is what they’ve evolved to eat for their optimal nutrition?