Some recipes don’t even measure water in cups, they just say “add water until the level is about 1/2″ above the level of the rice in the pot”. Some call for pre-soaking rice, others say you should never pre-soak.

So who is right? Why so much variation? You could follow two recipes on the web, and produce perfect rice with one and mushy crap with the other. Does that mean one was good and the other was bad? Maybe for you, but it’s possible that for someone else, the results are reversed, and the crappy recipe produces perfect rice, while your perfect recipe doesn’t.

The reason is because even if both of you follow the recipes exactly, there are still differences in the cooking range/stove you used, the pot you used to boil the rice, the exact amount of heat, etc. No cookbook or recipe can account for all these differences. This is why people’s results can vary so much.

I like a bit of math and science in my cooking, so I decided to put together this post. At the very least, it’ll explain why people’s results vary so much and why recipes are so different. Hopefully, it’ll help you produce perfectly cooked rice every time, without any guesswork.

What happens when rice cooks?

Uncooked dry rice grains have some moisture, but not a lot. The usual rice you buy in stores, both long grain and short grain, has about 12% moisture content, meaning each grain is 12% water by weight. Aged rice has a lower moisture content. If you buy aged basmati rice, for example, the moisture may be as low as 7-9%, depending on how long it was aged.

Cooking does two things to the rice. First, it hydrates the rice grain (adds moisture to it), making it swell and increase in size. Second, the heat cooks the rice grains, making them soft and slightly gelatinous.

Properly cooked rice has a moisture level between 58% and 64%. Anything below that range will feel hard and uncooked, and anything over that range will be mushy. You may prefer one end of the range rather than the other, depending upon the type of rice and your personal tastes.

So the goal of cooking is to increase the water content of the rice from 12% to about 60%, and also heat the interior of each grain for a sufficiently long period that it is cooked.

How much water should you add?

Water is used for two things – to hydrate and cook the rice, and to make up for water losses during cooking. The amount of water needed to hydrate the rice is fixed and based solely on the amount of rice, and can be calculated based on desired hydration levels. But the water lost during cooking is very variable, and depends on things such as:

• length of cooking time
• temperature of rice during cooking
• shape and size of the pot in which the rice is cooked
• how tightly the lid fits on the pot

Water for hydration

Let’s start with the easy part first, which is water needed for hydration.

Normally, we measure rice and water in cups. One cup of water is 240 ml, or 240 grams. One cup of rice varies, depending on the type of rice:

1 cup long grain rice = 185 – 190 grams

1 cup short grain rice = 195 -210 grams

Short grain rice can be packed tighter in the cup, so 1 cup of it weighs more than the same volume of long grain rice.

In order to hydrate this, we need:

1 cup short grain rice = 0.94 to 1.24 cups of water (for 58% – 64% hydration)

1 cup long grain rice = 0.85 to 1.12 cups of water (for 58% – 64% hydration)

You can pick the middle of the range and say that 1 cup of long range rice needs 1 cup of water for hydration, while 1 cup of short range rice requires a bit under 1.1 cups of water for hydration.

 Water losses during cooking

Next we need to figure out how much water will be lost during cooking, and make up for that. Water is lost during cooking due to evaporation. Ideally, we want to lose as little water as possible to evaporation. We can do this by:

• use pots which have tight fitting lids
• choose pots which are narrow and tall, rather than short and wide
• use high heat to bring water to a boil quickly, then immediately lower heat to simmer
• try to minimize cooking time

Consistency is the key to cooking rice, so don’t use a different pot each time you cook rice. Pick one pot and stick to it, so you can learn its quirks and adjust accordingly for them. The most important feature is should be the lid – pick one that has a tight fitting lid that doesn’t allow much steam to escape. The heavier the lid, the better. A tall and narrow pot will lose less steam than a wide and shallow pot.

Rice needs to cook at a simmer, which is a point just short of a boil. The temperature of a “simmer” is not that much lower than a boil, it’s just that the rate of heat delivery is such that the temperature is barely maintained, rather than having to keep losing excess heat through big clouds of steam. A “simmer” would be about 94-98 °C, as opposed to a boil which is 100 °C.

The easy way to do this is to bring the rice and water to boil, then reduce the heat drastically until it’s just enough to make bubbles slowly pop at the surface, and to produce a thin cloud of steam on the surface. Cooktops vary, so you will need to find the simmer setting on yours. On a typical cooktop that goes from 1 to 10, simmer might be somewhere between 1 – 3. You have to experiment and find out.

To reduce total cooking time, it’s important to bring the rice to a boil quickly. So use the high heat setting on your stove (and stand there and watch, or at least, don’t leave the stove for prolonged periods). As soon as it comes to a boil, reduce heat to simmer, and let it cook covered for the recommended amount of time.

To pre-soak or not?

This factors directly into cooking time, so I’m going to mention it here. In fact, we can also ask “should we wash the rice or not” while we’re at it.

What’s the difference between washing and pre-soaking? In washing, you add water to rice, swirl it around with your fingers, then drain the water out. Washing removes any loose starch grains adhering to the rice, and also removes any vitamins that the rice has been fortified with.

In the US, by law, all rice is sold fortified with certain B vitamins. This may or may not be useful to you. If you have a varied diet, if you occasionally take vitamin/mineral supplements, or if you already eat other foodstuffs supplemented with vitamins (anything made from flour, cereals, etc. will have added B vitamins), then you don’t really need the little bit of vitamins that were artificially added to the rice.

I always wash rice for 2 reasons:

• washing gets rid of loose starch granules, which make rice sticky after cooking
• washing can get rid of dirt and dust, after all, rice is a raw agricultural product

As I said, the downside is that you also lose those added vitamins. I don’t care about them because they are very minor, and I get enough vitamins from other foods anyway.

Now, what about pre-soaking? Yes, rice can be pre-soaked without washing. All you have to do is to not add an excess of water during the pre-soaking, so you don’t have to throw any water away. This way you can pre-soak, and then use the same water for cooking. Any vitamins that leach out remain with the water, and so are absorbed back into the rice when it cooks.

I think pre-soaking is a must, if you have the time. For any kind of rice, pre-soaking will always reduce the cooking time. Why? Because pre-soaking “wets” the interior of the rice grains, which allows them to cook much faster and more evenly.

When you cook rice, the heat has to get from the outside of the grain to the interior. This can take time. Let’s say you cook the rice for 15 minutes. While the outside of each grain reached cooking temperature right when you brought the heat down to a simmer, the inside doesn’t reach full cooking temperature until much later. So you can have the outside cooking for 15 minutes while the inside only cooks for 5 minutes. This means that either the inside is not fully cooked, or else the outside is overcooked and mushy.

Soaking allows water to reach the inside of the grains, which greatly improves heat transfer into the grain. So the inside starts cooking much sooner, compared to rice that wasn’t pre-soaked. This allows the total cooking time to be reduced, and for each grain to be cooked as evenly as possible.

Remember, the shorter the total cooking time, the less water you will lose during cooking, and the better the rice will taste, all else being equal.

So in summary, my recommendation is:

1. Always wash the rice first in a couple changes of cold water, specially if you are cooking long grain rice. Long grain rice should not be sticky, and washing makes it less sticky at the end.
2. Always pre-soak rice in cold water for about an hour, if you have the time. It will make the rice cook much more evenly, and can reduce cooking time in half.

You may choose not to wash or pre-soak the rice, but in that case, keep in mind the caveats mentioned above.

So, how much water do you need?

To figure the total amount of water needed, you should add the water required for hydration and the water losses during cooking. For long grain rice, you need 1 cup of water for 1 cup of rice, and for short grain rice you need 1.1 cups of water per cup of rice. This is hydration water only.

Next, you need to add water for cooking losses. This will vary greatly with your setup, the size and width of the pot, the lid, the temperature, etc. All those things mentioned above. If you wanted to be very exact, you could even perform an experiment:

1. Fill the pot with a measured amount (say 3 cups) of water – water  only, no rice. Close the lid, put it on the stove, bring to a rolling boil.
2. Immediately lower the heat to simmer, and note the time.
3. Wait for 30 minutes, then turn the heat off, and remove the pot from the stove. Let it sit on a counter top while it cools to room temperature.
4. Measure the amount of water left in the pot.

Let’s say you started with 3 cups and you end up with 2 cups after 30 minutes of simmer. So your rate of water loss  due to evaporation was 1 cup per 30 minutes. So if you expect to cook your rice in 15 minutes, you should plan for 1/2 a cup of lost water during cooking. For cooking 1 cup of long grain rice, you would add 1 cup of water for hydration plus 1/2 a cup for water loss, making 1.5 cups of water per cup of rice, for example.

If you don’t want to measure the rate of water loss, you will have to discover the right amount of water through trial and error. Here’s some brief pointers on how to begin:

All cooking times are measured from the point when you turn the heat down to simmer.

Rice that has not been pre-soaked typically cooks in 15 – 20 minutes, while rice that has been pre-soaked cooks in about 8-10 minutes.

If your pot is really bad in terms of retaining heat (loose fitting lid, too wide and shallow), it will probably lose about a cup of water to evaporation over the 15-20 cooking time of non-pre-soaked rice. This is the maximum amount of water you should start with (for example, cooking 1 cup of long grain rice = 1 cup water for hydration + 1 cup water losses = 2 cups water total). Chances are, your pot isn’t that bad, so you need to adjust down from 1 cup.

Typically, the range is:

• the best professional dedicated  rice cookers – very tight lids, zero water loss
• the worst random lidded pot found in the average kitchen – about 1 cup water loss per 20-30 minutes
• pot without a lid – all bets are off, your mileage will vary. Not recommended at all.

Depending on the pot you use, you’ll be somewhere in that zero to one cup range for water loss. I’d split the difference and figure on half a cup of water loss and adjust up or down from there through trial and error.

A note on proportions

Unless you cook exactly 1 cup of rice at a time, you will need to scale these amounts up or down. Let’s say you figure out through trial and error (or through the procedure described above) that you need exactly 1.5 cups of water per cup of long grain rice to make the perfect rice. Now let’s say you decide to cook for friends, so you end up cooking 3 cups of rice instead of 1. Can you scale up the water from 1.5 cups to 4.5 cups (3 x 1.5)?

If you’ve read this far, you know the answer is NO.

Remember, only the water needed for hydration scales with the amount of rice. The water needed to cover water  losses only scales with the cooking time, not with the amount of rice.

When you arrived at that 1.5 cups water per 1 cup rice number, what you were really doing was using 1 cup of water for hydration, and 1/2 a cup of water to cover water losses during cooking. So when you scale this up to 3 cups of rice, you will need 3 x 1 = 3 cups of water for hydration, but still only 1/2 a cup of water to cover water losses during cooking. Water losses during cooking only depend on the length of cooking time, and that hasn’t changed. Yes, it will take longer for 3 cups of rice plus water to come to a boil than it took for 1 cup of rice plus water to come to a boil, but we don’t measure that time anyway, we measure cooking time from after it’s come to a boil and the heat is reduced to simmer. This time doesn’t change whether you’re cooking 1 cup of rice or 3.

So in this case the correct amount of water needed for 3 cups of rice was 3.5 cups, and if you used 4.5 cups based on the simple calculation of multiplying everything by 3, then you used too much water and your rice will be soggy and mushy. This is one of the commonest mistakes that people make and why rice so often turns out bad.

In this respect, the older method of describing water quantity by “inches of water covering the rice was better. The idea there is that water mixes  with rice in a roughly 1:1 proportion, and the water level above the level of the rice represents water that will be lost during cooking. So if you know half and inch of water is lost during cooking, then no matter how much rice you have in the pot, half an inch of water on top of that will still be the cooking losses.

This method is also very hit and miss when it comes to sharing recipes, because nobody can say “half an inch on top of the rice works well” without seeing the pot you’re cooking with. This is because half an inch of a wider pot is a lot more water than half an inch of a narrow pot. If you use the same pot regularly, then you may make an observation that half an inch works well for that pot, or maybe 1/3 of an inch, or 2/3rd. This can serve you well for as long as you use the same pot, you’ll never have to measure water anymore. Just drop in the rice, add enough water to cover the rice plus 1/2 an inch over, and you’re all set. But if you change pots, you’ll need new numbers for the new pots. I don’t like this method much because eyeballing half an inch isn’t very accurate, I get much better results with measuring volumes in a measuring cup. But it still beats scaling up single  cup recipes naively, without separating out water of hydration and water losses of cooking.

What’s a good cooking time to aim for?

Rice tastes best when it’s cooked in the shortest time possible, but evenly (inside/outside of each grain cooked to the same degree).

Pre-soaking reduces cooking time, and for this reason alone I think it’s worth doing whenever you have the time to pre-soak. Always pre-soak for at least 1 hour.

Washing rice is generally a good idea, unless you are making certain short grain varieties that are meant to be sticky. In which case I would still pre- soak, but not wash (not drain the pre-soak water, just use it for cooking).

In my kitchen, when cooking basmati rice (my favorite) which has been pre-soaked for 1 hour, it takes about 8-10 minutes to cook the rice. The time is measured from after I’ve brought the pot to a rolling boil and lowered the heat to a simmer.

I use a heavy stainless steel pot for cooking rice. Since I have an induction cooktop which requires ferromagnetic pots, the pot is actually triple layered (magnetic stainless steel on the bottom, copper in the middle, regular stainless steel on the inside). I bring the pot to a boil on high heat (the highest setting on the cooking range), then immediately lower the heat to a simmer. The cooktop can be set by power level ( 1 to 10) or by temperature, and I set the simmer by temperature at 210 °F (boiling point is 212 °F). This is what I would call a “high simmer”, meaning that it cycles between just below boiling to a mild boil and then drops down again. A low simmer would be more like 200 °F. At these settings, it takes 8-10 minutes of simmer to cook the rice, regardless of the quantity of rice.

After cooking, always leave the rice on the stove (just turn the heat off), and let it sit covered and undisturbed for about 10 minutes before serving.

I am a fairly good cook now, but I prefer recipes that need little kitchen time and few ingredients. I don’t care if it takes 4 hours to cook, so long as I don’t have to spend more than 10 minutes in the kitchen. So in this blog I only write about stuff that is easy to make and doesn’t require a large commitment. Here’s my recipe for pork/rice with paprika. This is easily a main course for any meal.

Ingredients

• pork tenderloin: 2 pounds, defrosted
• rice: 1.5 cups, extra long grain, preferably basmati
• powdered paprika: about 2 heaped teaspoons
• powdered cumin: 1 teaspoon
• garlic powder: half a teaspoon
• ginger powder: half a teaspoon
• freshly cracked black pepper: half a teaspoon
• salt: to taste (I usually add 1-1.5 teaspoons)
• 2-3 medium onions, chopped
• 2-3 large green bell peppers, seeds removed, and chopped
• a couple teaspoons of oil: olive oil or canola
• 1 – 1.5 sticks of butter

Method

Start by turning on the oven to 450 degrees, and let the rice soak in a large pot with at least 2 inches of cold water covering it.

In a small bowl, mix all the dry spices and salt. Add enough oil to make a paste. Canola oil is best because of the high oven temperature, though you can use olive oil if you wish. Wash the pork tenderloins in cold running water, pat them completely dry with paper towels. Usually, tenderloins are sold in pairs, so a 2 pound package will have 2 tenderloins of approximately 1 pound each.

Put them in a roasting pan, and spoon the spice/oil mixture over them carefully. Spread the spice/oil paste until it completely covers the surface of the meat, making sure to baste both sides. Then adjust the tenderloins in the roasting pan so that they are about an inch apart, and the fat side is up. Pork tenderloins have very little fat, but they have a silvery membrane with a tiny bit of fat in it. You don’t have to remove the membrane, just put them with whichever side has more of the silvery stuff facing up. Make sure the tenderloins aren’t poking over the edge of the pan – if they are too long for the pan, fold the thinner end under itself so they fit within the pan.

After the oven has preheated to 450 F (the amount of time this can take varies with the oven, it will be at least 15 minutes if not more), put the pan with the tenderloins on a rack in the center of the oven, uncovered. Set the timer for 15 minutes at 450 F, to give the meat time to brown. After 15 minutes, turn the oven down to 250 F. Continue cooking until the internal temperature of the meat reaches about 150 F. This usually takes about an hour at 250 F (not counting the first 15 minutes at 450 F). Don’t cook any longer than an hour at 250 F, or the tenderloins will dry out — remember, tenderloins have very little fat and can easily get dry if you overcook them. After they have cooked, remove the pan from the oven and let it sit on a counter for at least 15 minutes before messing with it any further.

While the tenderloins are cooking, cook the rice. Make sure it’s soaked for at least 30 minutes (45 minutes is better). Then wash the rice in 2-3 changes of cold water. Drain the water, then add a measured 2 cups of cold water to it. Bring it to a boil, then turn the heat to low, cover the pot, and let it cook for 25 minutes. After it’s cooked, remove it from the stove and let it cool down – with the lid on. Do not remove the lid to speed up cooling. It should be allowed to cool for at least 15 minutes before it’s used further.

Melt the butter in a large skillet (has to be large, eventually the rice will be dumped here as well, later in the recipe). Add the chopped onions and chopped green bell peppers, and let them fry in the hot butter until they are slightly brown.

At this point, you could add other spices to the frying onions if you wished. I sometimes add crushed dry red pepper, and some Indian spices, but they are not necessary.

If you time things right, the onions and peppers will finish frying about 15 minutes after the pork tenderloins are done and the rice is cooked. It’s important that both the tenderloins and the rice be allowed to cool on a counter for at least 15 minutes after removing from the stove or oven, before you use them further in the recipe.

Cut the tenderloins into small cubes (I prefer them really small, like quarter-inch cubes), and toss them in the pot with the onions and green peppers. There will be some fat that has drained out into the roasting pan. It’s not a lot, and it’s very flavorful. If you like, you can drain this fat directly into the skillet with the onions as well. If you’re trying to cut down on fat, oh well, don’t bother. Stir everything around for a minute or two.

Finally, dump the rice into the skillet. Turn the heat down to medium-low, stir occasionally to mix the rice in with the meat and fried onions/peppers/spices. The goal is the mix everything thoroughly, to coat the rice grains with butter from the pan so they don’t stick together. It’s now ready to serve.

Just before serving, I like to make a final check on the salt. If you had about 1.5 teaspoons of salt in the original spice rub used for the meat, and if you didn’t toss the liquid that drained out into the roasting pan, but added it to the skillet along with the rice, then you should have enough salt in the prepared dish. But if you tossed the roasting liquid or didn’t have enough salt to begin with, you might want to add a bit more to the skillet at this time. At any rate, you must check for salt before serving, very likely it will need some adjustment. The easiest way to ruin a dish, specially a meat dish, is to not have enough salt. Salt brings out the flavors in meat. I also add some chopped cilantro right before serving, but that’s optional. Mix it all up and serve hot.

Makes about 3-4 servings for hungry adult males. More, if you’re a girl.

Notes

This is very much “comfort food”, which I identify as basically any form of meat (roasted is more “comforty”) plus a starch, suitably salted. The starch could be rice or potatoes, both have their uses. This sort of food has a very primal appeal to our taste buds, possibly going back to when our ancestors first discovered the miracle of cooking, roasting meats and roots at their campfires. Onions and garlic and their botanical kin were probably among the first flavors to be added to food. This is an extra dimension that food holds for me, to be able to use it as a means to relate to our ancestors, to see and smell and taste what they did. Historical food has the same attraction, which is why I sometimes try out historical recipes from Roman times, or medieval food.

Like most stuff with spices, this can be easily refrigerated. If you are cooking for one, simply divide it up into portions in ziplock bags. It easily lasts 2-4 days in the refrigerator. Just nuke it in a microwave before serving.

Learning how to add salt is one of the earliest cooking skills that needs to be mastered. Unless you are following a recipe exactly, you’ll have to make a decision about how much salt to add. This is not a trivial decision; it’s one of the most important things you can do to enhance or ruin the flavor of food.

There is no exact science to it. Use good salt. Iodized salt sucks. I prefer kosher salt for general use, sea salt for specific recipes. Start by tasting whatever you intend to salt, to get a “baseline flavor”. Add salt sparingly, in steps. You can always add more, but taking it away is harder. Don’t dump it on to one spot in the food, sprinkle it evenly across all the food, then mix thoroughly and taste it. Does it taste better than the “baseline” taste? How does it taste different? You sort of have to learn this for yourself, because no one can explain to anyone else what “properly salted” ought to taste like. You have to experience it yourself. Adding salt in steps, a little bit at a time, then checking the taste, is the surest way to learn. After some time, you’ll be able to taste the food once, eyeball the amount of food, and know how much salt to add without measuring a damn thing. But it takes a little bit of practice. To me, the ideal amount of salt is that which makes the food just short of salty. Meaning, I shouldn’t be able to taste the salt specifically (unless I’m eating potato chips), but the flavors in the food should be maximally developed by the salt. You may prefer a bit more, but you will very likely not prefer less. Just experiment a bit and see what you like.

I’ve come across a number of articles that talk about the importance of a change in diet in human evolution. The theory is that human diet suddenly improved dramatically, and this marked increase in the availability of calories and nutrients was responsible for the growth of the brain. The improvement in diet is generally tied to either the switch from a primarily herbivorous diet to meat eating, and/or to cooking.

Both make sense in terms of calories and nutrients. Meat is certainly a more densely packed source of nutrients than plants. And cooking increases the bioavailability of nutrients, as it breaks up cell walls and structures that hinder our digestive enzymes from reaching the goodies inside cells.

Of course, this still leaves us without an actual mechanism. Evolution requires heritable changes in the genome. These happen largely by  accident, though their selection depends upon what is advantageous to survival and reproduction. At this point, we don’t know very well exactly which genes are responsible for the differences in our brains, say compared to chimpanzees. We don’t know when these changes first appeared. We don’t know what connection they have to an improved diet.

So one part of evolution, that which is related to the genomic changes responsible for our large brains, is mostly unknown to us. Therefore, I think that ideas such as the change-in-diet leading to big brains scenario, tend to ignore the unknowns and focus only on the natural selection side of evolution. They make certain assumptions, for example, that a large brain will be selected, because it enhances survival and the chance to reproduce. This can be somewhat justified if one thinks about  it (large brains, specially the growth of the forebrain is what allows us to make long range plans, analyze complex problems, etc.), and also there is fossil evidence that shows that in fact it was selected. Then there is the assumption that a large brain requires a nutrient rich diet, which can also be justified on the basis of the caloric expenditure in maintaining a large brain. A commonly offered statistic is that for a person at rest, of the amount of energy required to stay alive, the brain uses 20%, or 1/5th. The brain is obviously much less than a fifth of the body in terms of mass, yet it uses an extraordinary amount of energy, in proportion. If you keep the total mass of an organism constant, but increase the size of the brain in proportion to the rest of its body, then such an organism will require a more nutrient rich diet. In effect, you have increased its energy requirements, but have not given it bigger jaws to chew food, a bigger gut to digest it, bigger claws to hunt with, etc.

In fact, both anatomy and the fossil record show that humans became less capable of acquiring food as their brains grew, if we look solely at such biological markers such as tooth/jaw size. Homo erectus had smaller jaws than his ancestors, which would have made it harder for him to grind foods down and extract the most energy from them. Our gut became smaller, and less capable of extracting energy from plants. Our muscles became weaker, less capable of overpowering other animals through brute strength alone.
One would think that the timing of these changes would have some correlation with our behavior or change in diet, or the control of fire (for cooking). Unfortunately, the timing is much harder to pin down. No one really knows when humans first learned to control fire. Homo erectus, with his small jaws, evolved 2 million years ago, but the evidence for the widespread use of fire by humans at this time is scanty at best. Most anthropologists don’t believe that fire was used by humans this early, at least, not in any regular, controlled manner, such as would be needed for cooking. Soft tissues don’t fossilize well, so while we can study humans and chimps today and recognize that the chimp gut is much more suited for eating raw plant material than the human gut, we don’t really know when we evolved our more carnivorous digestive systems.

This leaves a chicken versus egg conundrum. Which came first, the big brain or the adaptations to the big brain lifestyle? Which was responsible for the other? This may be a silly question on the face of it, because obviously one is useless without the other. What’s the point of having a modern jaw or gut if you don’t also have the bigger brains that give you the means for filling that gut with food? On the other hand, how do you sustain that brain and give it energy without eating a more nutrient-rich diet?

So it seems that speaking in terms of absolute causality, one thing causing the other is somewhat simplistic. They probably both happened together, one reinforcing the other, and happened gradually. We didn’t go suddenly from a chimp-sized brain to a human-sized one, as we know from the fossil record. There are many intermediate stages of the brain growing progressively larger. The change in diet, therefore, and the behavioral changes accompanying both the change in diet and the larger brain, must have happened concomitantly.

It’s interesting at this point to bring in the factor we’ve ignored all along – that there must be genomic changes that produce all the anatomical differences – jaws, teeth, gut and brains. These genomic changes also need to be accounted for, and tied into the selection mechanism. A high nutrient diet is obviously not enough; otherwise large cats such as lions and tigers would be smarter than us. They might not cook, but they eat enough high nutrient food to be able to support bigger brains. They have evolved as long as us, why didn’t they learn to cook,  why didn’t they evolve bigger brains?

This brings us back to selection, and fuzzier areas of anthropology such as social behavior and interactions, etc. We have bred dogs for a few thousand years, for example, and we have breeds of dogs today that look very different from each other. Not only is there is a difference in size and color of the fur, but there are also differences in the brain. Some breeds of dogs are smarter than others. We did this by a fairly simple process of selection – pick dogs that have the traits you want, breed them to produce a new generation, keep selecting for the desirable traits and reinforcing them through successive generations. Even with no knowledge of DNA or even Mendellian genetics, our ancestors were able to do this for dogs. We have also bred cows, pigs, goats, sheep, etc. – the modern domesticated forms of which are quite different from their wild ancestors. Not to mention the similar and parallel process of breeding food plants.

So even without postulating major and sudden changes in the genome, those which suddenly introduced a “game changer” mutation so far as the brain was concerned, it’s possible to see that humans could have become progressively smarter simply if the natural variation in smartness among a population was selectively reinforced over generations, the same way we breed dogs. Of course, this doesn’t mean that you can breed dogs to a human level of intelligence, there may well be certain required mutations, and these have to happen first. You can’t select for what doesn’t exist. But at a point where we don’t fully understand the nature of these key mutations, we can’t really talk about how essential they were. Perhaps they could happen in other species too. Perhaps there are a dozen different ways to get the same result, and if mutation “A” doesn’t happen, mutation “X” can provide the similar benefits. I’d rather not speculate about this until we have more information to speculate with.

So I think such articles (as the one referenced above, which talks about the relation of diet to human evolution) speculate about the remainder of the problem, the mutually reinforcing effect of the selection of traits which are part of the natural variability of a population, and the behavioral consequences of selecting such traits. You set a species on a certain path, on which a greater reliance on the brain cuts out some options while expanding others, and the options that are promoted require even greater brain power to work well. It’s interesting to speculate what put us on this path, why we seem to be the only species on it. What set of circumstances came together at the right time for this to happen. The drying climate and spread of grasslands, the change from an arboreal to a savannah type lifestyle, the appearance of bipedality at this critical juncture when these big new ecological niches suddenly opened up, the development of more and more hand flexibility with a greater range of movement in the opposable thumb (compared to other primates), the social interactions, etc. There were so many changes happening at roughly the same time to the same species, somewhere this set us off on a path to bigger brains.

The article that set me off on this line of thought, of course, talks about something narrower. It talks about the relationship of cooking to gender roles, the development of the male-female bond, which is marriage today. This seems less an evolutionary question than an anthropological one. The evolutionary part is the importance of cooked food in the development of our brains, which I have speculated about. The anthropology part is relating this importance to something else, namely male-female pairing. I am not qualified to speculate about the anecdotal evidence offered about some primitive societies where food is more important than marital fidelity. Nor do I have any evidence that women tended the home fires, though it seems likely if men were the hunters and spent less time at the home camp. This seems to be supported by fossil evidence, such as hunting related injuries, as well as by anthropological evidence. You can speculate that the importance of cooked food was critical enough to shape our behavior patterns in other ways, such as pair-bonding between males and females. But just because a theory seems to make sense doesn’t mean it’s true, so I guess we’ll need to see some more physical evidence before placing much value on it.