ACT Reading Practice Test 28

NATURAL SCIENCE: The Eating Habits of Related Primates

Scientists know very little about the eating habits of our ancestors who lived over two and a half million years ago. To solve this problem, scientists have started examining chimpanzees’ hunting behavior and diet to

Line 5 find clues about our own prehistoric past. It is not difficult to determine why studying chimpanzees might be beneficial. Modern humans and chimpanzees are actually very closely related. Experts believe that chimpanzees share about 98.5 percent of

10 our DNA sequence. If this is true, humans are more closely related to chimpanzees than to any other animal species. In the early 1960s, Dr. Jane Goodall began studying chimpanzees in Tanzania. Before the 1960s,

15 scientists believed that chimpanzees were strict vegetarians. It was Goodall who first reported that meat was a natural part of the chimpanzee diet. In fact, Goodall discovered that chimpanzees are actually very proficient hunters. Individual chimpanzees have been

20 known to hunt and eat more than 150 small animals each year. Among the chimpanzees’ favorite prey are the red colobus monkey, feral pig, and various small antelope species. The red colobus monkey is one of the most important animals in the chimpanzees’ diet. In one
25 notable study, the red colobus monkey accounted for more than 80 percent of the animals eaten by one group of chimpanzees. Despite these findings, scientists still maintain that chimpanzees are mostly fruit-eating creatures. In fact,

30 meat composes only about 3 percent of the chimpanzee diet. This is substantially less than the quantity of meat consumed by the average human. Studies show that chimpanzees do most of their hunting in the dry season. August and September appear to be the most popular

35 months for hunting. During the dry season, food shortages in the forest cause the chimpanzees’ body weight to drop. Consequently, chimpanzees supplement their diets with meat. During the height of the dry season, the estimated meat intake is about 65 grams of meat per day

40 for adult chimpanzees. This is comparable to the quantity of meat eaten by modern human societies whose members forage when other food sources are scarce. The chimpanzees’ eating habits also closely resemble those of the early human hunter-gatherers.

45 Humans and chimpanzees are the only members of the Great Ape family that hunt and eat meat on a regular basis. However, like chimpanzees, humans are not truly carnivorous creatures. In fact, most ancient humans ate a diet composed mostly of plants, and even

50 modern humans are considered omnivores because they eat fruits, vegetables, and meat. Most people assume that food choices are based solely on nutritional costs and benefits. Although it is clear that the hunting habits of chimpanzees are

55 guided mostly by nutritional needs, some aspects of the chimpanzees’ behavior are not well explained by nutrition alone. Researchers suggest that chimpanzees might hunt for social gain. For instance, a male chimpanzee might try to demonstrate his competence to other male

60 chimpanzees by killing prey. Chimpanzees may also use meat as a political tool to punish rivals and reward friends. However, a study also shows that female chimpanzees that receive large portions of meat after a hunt have healthier and stronger offspring. This indicates

65 that there might be reproductive benefits to eating meat as well. The information that scientists have been able to gather regarding chimpanzee hunting behavior is shedding some light on the eating habits of our ancestors.

70 Further investigation is needed, however, to provide stronger evidence regarding this aspect of man’s prehistoric past.