Which of these would most likely contribute to the extinction of a species?
a. an increase in its genetic variability
b. a decrease in the number of its competitors
c. the extinction of species at higher trophic levels
d. the extinction of species at lower trophic levels

Which of the following best describes the expensive tissue hypothesis? brains require more energy, so the gut had to be reduced, and larger brains and tool use led to higher quality diets. increasing body size means that homo neanderthalensis had to include more fat in its diet. brains require more energy, so the gut had to be reduced as brains got bigger. brains require more fat, so the gastrointestinal viscera (gut) had to expand, and hands were needed to acquire more food.