Paleoanthropologists have long believed that the growth of the human brain became possible only because the consumption of high-calorie meat allowed human ancestors to survive with smaller stomachs, freeing energy for the development of larger brains. However, recent research from biological anthropologists on the scavenging, hunting and eating habits of the few remaining hunter-gatherer peoples calls into question this continued reliance on an increase in meat intake as the sole explanation for human brain size. Based on their observations of our ancestral hunter-gatherers’ modern counterparts, the biological anthropologists concluded that the depiction of hunter-gatherer diets as meat-centric fails to reflect both the variety and variability of such diets.

To understand the extent of dietary variability, biological anthropologists first evaluated the percentage of annual calories derived from meat across several modern hunter-gatherer populations. They discovered that, while a handful of populations were essentially carnivorous because of their ability to hunt or fish in sufficient quantities to obtain the majority of their calories from meat, most hunter-gatherers are more appropriately described as omnivores, as up to 70% of their calories come from non-meat sources. The carnivorous groups, such as the Inuit people, are found exclusively in the Arctic; this geographical isolation suggests their eating pattern is not broadly reflective of early hominid practices. The biological anthropologists hypothesized that, because of the greater prevalence of foragers who rely on foods other than meat, an examination of the caloric content of the omnivorous hunter-gatherer diet would provide more clarity about the causes of human brain expansion.

Homing in on the diets of the omnivorous groups, the researchers found that, in periods when hunting results are bleak, the alternative foods that hunter-gatherers consume vary greatly. In the absence of meat, they consume high-calorie plant substances, such as root or stem tubers, nuts, and even grains, with distinct populations thriving on the particular plant sources available in their immediate habitats or those within easy range. The researchers concluded that calories from meat were likely not the only cause of brain expansion and that the supplemental calories provided by fallback fare were just as essential to providing early hominids with the energy to fuel brain growth. Complementary scientific inquiries also indicate that early man’s ability to locate and combine available plant products into a calorie-rich diet contributed more substantially to the hallmark feature of the human species than did hunting and fishing.

1. In the second paragraph of the passage, the author is primarily concerned with

A) presenting findings that dispute the logic of a prevailing assumption
B) critiquing the methodology used in a recent research undertaking
C) explaining a theory that influenced numerous fields of study
D) exploring factors that invalidate a long-standing hypothesis
E) describing the results of a scientific inquiry


2. Which of the following statements about the human brain is supported by the passages?

A) The human brain is larger than the human stomach.
B) Holding body size constant, the brains of vegetarians tend to be smaller than the brains of people who obtain at least 30% of their calories from meat.
C) The human brain allowed early man to hunt more successfully than other primates.
D) Human brain development was facilitated by changes in the digestive system.
E) The brains of modern hunter-gatherers tend to be larger than the brains of people who eat a diet containing nutrient-poor processed foods.


3. The passage is primarily concerned with

A) elucidating the eating habits of early members of the homo genus
B) demonstrating how interdisciplinary cooperation yields more accurate scientific hypotheses
C) comparing modern humans to their hominid precursors to explain existing genetic variety within the homo sapiens species
D) proving the superiority of a balanced diet as compared to a diet heavily reliant on meat
E) correcting a misconception about the origins of one aspect of human anatomy


4. Which of the following, if true, would most directly contradict the assumption that omnivorous diets are more broadly reflective of early hominid practices than are carnivorous diets?

A) During the period when hominids were diverging from other primates, the Arctic climate covered more of the earth than it does today.
B) Few of the fossil teeth recovered to date show wear patterns consistent with regular consumption of high-calorie plant substances.
C) The game animals available to early hominids were much larger than the prey available to today’s hunter-gatherer populations.
D) Many modern humans avoid meat because they lack an enzyme that allows the body to convert meat proteins efficiently into nutrients.
E) Existing hunter-gatherer people have a more expansive range than did early hominids.