No problem.
This morning when I was eating, I remembered something important regarding fire and wanted to tell you once I hopped on.
There was a point in history, where homo sapiens could've gone down the route of either evolving their brains or evolving their stomach.
Not both. Why? Because both are extremely high energy to spend resources on. So it was either or.
With the advent of fire, our stomachs had easier times digesting (although I can see that you disagree with this).
Cooking food chemically breaks down parts of the meat. Our stomachs also chemically break down parts of the meat to digest. So if the fire does it for you, then your stomach has less work.
So, we did not need the evolutionary trait for a better stomach.
Instead, our resources went to our brain. That's how we are so smart.
Homo Erectus may have done fire before us, but we are not sure if it was for cooking. Because fire was originally for light and heat when humans first used it, and later for tools, social activies, etc.
Scientists have found that among several primates, the restriction of feeding to raw foods during daylight hours limits the metabolic energy available.
[51] Genus
Homo was able to break through the limit by cooking food to shorten their feeding times and be able to absorb more nutrients to accommodate the increasing need for energy.
[52]
In general the Homo genus has had larger brains than other primates, not just Sapiens.
"Before the advent of fire, the hominid diet was limited to mostly plant parts composed of simple sugars and
carbohydrates such as seeds, flowers, and fleshy fruits. Parts of the plant such as stems, mature leaves, enlarged roots, and tubers would have been inaccessible as a food source due to the indigestibility of raw
cellulose and
starch. Cooking, however, made starchy and fibrous foods edible and greatly increased the diversity of other foods available to early humans. Toxin-containing foods including seeds and similar carbohydrate sources, such as
cyanogenic glycosides found in
linseed and
cassava, were incorporated into their diets as cooking rendered them nontoxic.
[54]
Cooking could also kill
parasites, reduce the amount of energy required for chewing and digestion, and release more nutrients from plants and meat. Due to the difficulty of chewing raw meat and digesting tough proteins (e.g.
collagen) and carbohydrates, the development of cooking served as an effective mechanism to efficiently process meat and allow for its consumption in larger quantities. With its high caloric density and content of important nutrients, meat thus became a staple in the diet of early humans.
[55] By increasing digestibility, cooking allowed
hominids to maximize the energy gained from consuming foods. Studies show that caloric intake from cooking starches improves 12-35% and 45-78% for protein. As a result of the increases in net energy gain from food consumption, survival and reproductive rates in hominids increased.
[56] Through lowering food toxicity and increasing nutritive yield, cooking allowed for an earlier weaning age, permitting females to have more children.
[57] In this way, too, it facilitated population growth."
Fire has also caused easier chewing (noticeable today as well, via sapien micro-evolution): Before their use of fire, the hominid species had large
premolars, which were used to chew harder foods, such as large seeds. In addition, due to the shape of the molar cusps, the diet is inferred to have been more leaf- or fruit-based. Probably in response to consuming cooked foods, the molar teeth of
H. erectus gradually shrank, suggesting that their diet had changed from tougher foods such as crisp root vegetables to softer cooked foods such as meat.
[59][60] Cooked foods further selected for the differentiation of their teeth and eventually led to a decreased jaw volume with a variety of smaller teeth in hominids. Today, a smaller jaw volume and teeth size of humans is seen in comparison to other primates.
[61]
Basically, without fire cooking, we would've been dumb apes.
There are obviously criticisms to this theory, which, all theories have some form of criticism. But overall, I find this theory strong.
IDK if you read any of this, so TLDR; fire made humans high IQ
