This passage is adapted from an article by Mary Evans that originally appeared in The Economist (© 2009 by Mary Evans).
- You are what you eat, or so the
- saying goes. But Richard
- Wrangham, of Harvard
- University, believes that this
- is true in a more profound
- sense. It is not just you who
- are what you eat, but the
- entire human species. And
- with Homo sapiens, what
- makes the species unique in
- Dr. Wrangham’s opinion is
- that its food is so often cooked.
- Cooking is a human universal.
- No one other than a few
- faddists tries to survive on
- raw food alone. And the
- consumption of a cooked
- meal in the evening is normal
- in every known society.
- Moreover, without cooking,
- the human brain could not
- keep running. Dr. Wrangham
- thus believes that cooking and
- humanity are coeval.
- In fact, as he outlined to the
- American Association for the
- Advancement of Science, in
- Chicago, he thinks that cooking
- and other forms of preparing
- food are humanity’s “killer
- app”: the evolutionary change
- that underpins all of the other
- changes that have made people
- such unusual animals.
- Humans became human with
- the emergence of a species called
- Homo erectus. This had a
- skeleton much like modern man’s
- —a big, brain-filled skull and a
- narrow pelvis and rib cage, which
- imply a small abdomen and thus
- a small gut. Hitherto, the
- explanation for this shift from the
- smaller skulls and wider pelvises
- of man’s apelike ancestors has
- been a shift from a vegetable-
- based diet to a meat-based one.
- Meat has more calories than
- plant matter, the theory went.
- A smaller gut could therefore
- support a larger brain.
- Dr. Wrangham disagrees. When
- you do the sums, raw meat is
- still insufficient to bridge the
- gap. He points out that even
- modern “raw foodists,” members
- of a back-to-nature social
- movement, struggle to maintain
- their weight—and they have
- access to animals and plants
- that have been bred for the
- table. Pre-agricultural man
- confined to raw food would
- have starved.
- Start cooking, however, and
- things change radically. Cooking
- breaks starch molecules into
- more digestible fragments. It
- “denatures” protein molecules,
- so that their amino-acid chains
- unfold and digestive enzymes
- can attack them more easily.
- And heat physically softens
- food. That makes it easier to
- digest, so even though the
- stuff is no more calorific, the
- body uses fewer calories dealing
- with it.
- In support of his thesis, Dr.
- Wrangham, who is an
- anthropologist, has ransacked
- other fields and come up with
- an impressive array of material.
- Cooking increases the share of
- food digested in the stomach
- and small intestine, where it
- can be absorbed, from 50% to
- 95% according to work done
- on people fitted for medical
- reasons with collection bags at
- the ends of their small intestines.
- Another telling experiment,
- conducted on rats, did not rely
- on cooking. Rather the
- experimenters ground up food
- pellets and then recompacted
- them to make them softer. Rats
- fed on the softer pellets weighed
- 30% more after 26 weeks than
- those fed the same weight of
- standard pellets. The difference
- was because of the lower cost
- of digestion. Indeed, Dr.
- Wrangham suspects the main
- cause of the modern epidemic
- of obesity is not overeating
- but the rise of processed foods.
- These are softer, because that
- is what people prefer. Indeed,
- the nerves from the taste buds
- meet in a part of the brain called
- the amygdala with nerves that
- convey information on the
- softness of food. It is only after
- these two qualities have been
- compared that the brain
- assesses how pleasant a
- mouthful actually is.
- The archaeological evidence for
- ancient cookery is equivocal.
- Digs show that both modern
- humans and Neanderthals
- controlled fire in a way that
- almost certainly means they
- could cook, and did so at least
- 200,000 years ago. Since the
- last common ancestor of the
- two species lived more than
- 400,000 years ago, fire-control
- is probably at least as old as
- that, for they lived in different
- parts of the world, and so could
- not have copied each other.
- Older alleged sites of human
- fires are more susceptible to
- other interpretations, but they
- do exist. And traces of fire are
- easily wiped out, so the lack of
- direct evidence for them is no
- surprise. Instead, Dr.
- Wrangham is relying on a
- compelling chain of logic. And
- in doing so he may have cast
- light not only on what made
- humanity, but on one of the
- threats it faces today.
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The author characterizes people who consume only raw food as:CorrectIncorrect
When the author states that Dr. Wrangham does not believe that raw meat is sufficient to “bridge the gap” (lines 54-55) she most nearly means that:CorrectIncorrect
Based on the information provided in the passage, which of the following best describes Neanderthals’ dietary habits:CorrectIncorrect
The passage indicates that cooking food results in which of the following changes?
I. the decomposition of starch molecules
II. the unfolding of amino acid chains
III. decreased ease of digestionCorrectIncorrect
According to Dr. Wrangham’s theory, the leading cause of obesity in modern human beings is:CorrectIncorrect
Based on the experiment described in the seventh paragraph (lines 92-118), one group of rats did not gain weight because:CorrectIncorrect
According to the passage, the evolution of modern humans’ ribcage and pelvic structures has traditionally been considered the result of early humans’:CorrectIncorrect
As it is used in the first paragraph, the word “coeval” (line 24) most nearly means:CorrectIncorrect
Given the information provided in the passage, it can be reasonably inferred that if a person consumes two equally tasty foods, one hard and one soft, the amygdala will respond by:CorrectIncorrect
The passage indicates that evidence for human ancestors’ ability to control fire as long as 400,000 years ago is primarily based on:CorrectIncorrect