Why does this recent discovery about the Galapagos finches prove that it’s often challenging for scientists to determine when two groups of individuals are separate species? What factors do scientists need to consider when determining whether a species is a new species or part of an existing species?

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.