How can a seemingly valuable behavior evolve in one species but not in another

How can a seemingly valuable behavior evolve in one species but not in another

QUESTION 1 (5 POINTS)
How can a seemingly valuable behavior evolve in one species but not in another? For example, primates can vomit but rodents cannot. Mention genes and natural selection in your answer.

QUESTION 2 (5 POINTS)
Many people believe that we use only ten percent of our brains. Use evidence about the brain to evaluate such a claim.

QUESTION 3 (5 POINTS)
How are neurotransmitters, membrane receptors and ion channels related?

QUESTION 4 (5 POINTS)
What are three differences between rod and cone photoreceptors?

QUESTION 5 (5 POINTS)
How would you describe the difference between what the retina does and what the striate cortex does?

QUESTION 6 (5 POINTS)
Explain how hair cells transduce sound into elecrical potentials.