It might reasonably have been expected that the adoption of cooking by early humans would not have led to any changes in human digestive anatomy.
Topic
Evolutionary effects on humans of cooking
Framework
Old / New
Main Point
People used to think that humans' use of cooking probably didn't have any effect on digestive anatomy, but now we think we've evolved so much to having a cooked diet (our teeth, jaws, and possibly intestines) that we'd be unable to survive in most cases on a raw food diet.
Summary
FIRST PARAGRAPH
- It might reasonably have been expected that X. After all, Y. However, current evidence suggests ...
These rhetorical features warn us about what the passage will likely be doing. We open with an allusion to Old beliefs, or Typical beliefs, or usual assumptions, and then we get our Author's (but / yet / however / recently) Pivot right after that.
Upon reading the first sentence, we should already be pausing and saying to ourselves,
And we'd be right. That's essentially the main point right there.
From the "However" until the end of the first paragraph, we're getting the current evidence for the fact that cooking has changed us: - we wouldn't be able to live off raw food (except under special circumstances) - this suggests we've now evolved to a form that requires cooked food - there has actually been plenty of time (on an evolutionary scale) for these changes to take place, since we have evidence that cooking started over 250,000 years ago.
The author crystallizes her takeaways at the end of the first paragraph, saying
Because we could cook, we were able to eat a diet with more high caloric density food. Because we were able to eat that type of food, our bodies adapted ways to optimize eating that type of diet, and now we're so adapted to a cooked diet that we'd struggle to live on a raw diet.
SECOND PARAGRAPH
The topic sentence here indicates that this paragraph will be discussing questions about how we've changed, to be more adapted to a cooked diet. - there's a known change in the fossil record to our tooth and jaw size around 100,000 years ago. - the author thinks that was the restul of adapting to cooked food. - she thinks it's possible that cooking started over 1 million years ago and some adaptations occurred then, but then the adaptations seen around 100,00 years ago were ones that happened when we invented the concept of boiling water.
THIRD PARAGRAPH
Since this paragraph begins by saying , it looks like this paragraph still falls under the framing idea at the beginning of the 2nd paragraph: important questions therefore arise
We know that our guts are different from those of other great apes. Some people think it's because we eat more raw meat than apes do. This author thinks that "adaptations to cooking" could just as easily explain it.
She suggests a future research direction in the final sentence, to help determine which hypothesis is more likely.