We discuss a lot of science here and for a change of pace I was thinking the other day about why I think humans were meant to consume starch for at least a goodly portion of our energy. I'm not going to talk about obscure cultures most of you never heard of and Americans and most cultures around the world have never eaten like. I'm not going to talk the minutia of evolution, genetic adaptation, extinct fauna, etc. etc.
I'm going to talk look at that body of yours. Clearly we've evolved or adapted or whatever over the centuries to eat both plant and animal foods. Look at your mouth for starters. And now look at the kitty's mouth below.
I don't know about you, but when I compare my smiling mug to this fella, I don't see a lot of similarities. This fella is a carnivore. Kit cat here has teeth designed to rip into flesh and not so much for chewing. I, and you, on the other hand don't possess particularly fang-like canines and we've got large flat molars.
But I'm not done with the mouth yet. Digestion begins in our mouths starting with amylase to break down starch. Kit cat up there has no amylase because kitty is a carnivore. So why do humans have salivary amylase? Perhaps it's as simple as that we're designed to consume carbohydrates.
OK so let's fast forward all the way down the digestive tract through the small intestine. We clearly have nothing in common with herbivorous ruminants so we can ignore them, but what of other omnivorous creatures? Enter the hind-gut fermenter. Of course we can't use the mirror for this comparison so I'll have you compare the digestive systems below. For this comparison, let's take a look inside this cute fella.
And let's compare that to the human digestive system:
As you can see, the rabbit is a hindgut fermenter, humans are not. The cecum is a functional organ in the hindgut fermenter, it's more an area/region in the human digestive system. Indeed our appendix is thought to be by many our true equivalent to the cecum. The purpose of the cecum is so that species so equipped retain material - cellulose and soluble fibers and such - wherein bacteria can breakdown such fibers to extract usable energy for the animal. Interestingly enough, such animals will also often engage in coprophagy to gain access to nutrients that might otherwise go wasted.
Long story short, does it seem that humans are well suited to eating non-starchy vegetation for energy? I think when we approach this whole notion of the best diet or a healthy diet, too many of us do so from the starting point of weight loss rather than true health and optimization. Since the first time I started reading Mark Sisson's blog, I always wondered about this notion that our primitive ancestors would somehow expend energy to forage for the foods with the highest fiber content and lowest starch content. My common sense says to me that plants have been storing energy as starch for a very long time in the history of this planet we inhabit. My common sense also tells me that if hindgut fermenters can have the smarts to eat their own feces - can't be too palatable if you ask me - to extract energy, we humans certainly learned quickly which species of plants provided us with the most energy and tended to eat those. Which is not to say that we probably didn't eat a lot of fiber along the way in our quest to fuel our bodies, but we were seeking the starch (and sugars).
Common sense tells me that a diet of mostly meat and green leafy vegetables is not optimal for fueling the human body for the long haul. This is not to say such a diet doesn't have its place in the treatment of certain conditions, obesity included. But this blogger is coming to the realization that starch is a natural human food that our bodies are "built" to use for energy.
Unfortunately in our modern world, starches have been refined like sugar. On their own, neither is all that palatable, starches - especially refined - are actually the least palatable food I can think of. So we humans started combining them with sugar and fat. Welcome to the cafeteria ...