While walking through a natural history museum, your little cousin points out the skull of an australopithecine with a large crest on the top and asks you what its purpose was. to simplify a complicated evolutionary trait, you tell your cousin that:

these hominids had muscles to eat hard foods such as nuts

Explanation:

Australopithecine refers to several species of an extinct bipedal primate. Researchers disagree on which of the species evolved into the homo in Africa two million years ago. However, observation of their remains indicates that australopithecines possessed larger post canine teeth with more enamel that modern humans and apes, which could demonstrate their consumption of hard food like nuts.

the first part is ocean

explanation:

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.