Jaguars, Cheetahs, and Other Great

¶ … jaguars, cheetahs, and other great cats to have mostly slow-twitch, non-fatiguing muscles in their legs or mostly fast-twitch, quickly fatiguing muscles? What kinds of animals might have mostly the opposite kind of muscles?

One of the issues with evolution is that it favors behaviors and physiological changes that are conducive to survival of the species. If a mutation causes something negative, then there are fewer of that species to produce and over time, that mutation causes the need for another adaptation. In terms of muscle development, in mammals and humans there are fast-twitch fibers and slow twitch fibers. The fast-twice have fast contractions and tire quickly, but provide quick bursts of energy. Slow-Twitch fibers have fewer contractions and do not tire easily. Mammals rely on slow-twitch fibers for non-strenous activities, but for activities that are survival essential or require quickness, the fast-twitch muscles are used. Animals that do not need prolonged speed, but have protection like spines, skin poisons, or armor would not need to use fast-twitch muscles since their survival depends on other adaptations. Predators like the great cats would need mostly fast-twitch muscles to outrun and capture prey (Kalat, p. 234).

Part 2 -Human infants are at first limited to gross movements of the trunk, arms, and legs. The ability to move one finger at a time matures gradually over at least the first year. What hypothesis would you suggest about which brain areas controlling movement mature early and which areas mature later?

Human infants are quite dependent on parenting for a longer portion of their lives than many other mammals. Development of functions is likely controlled by need and what the infant must be able to do at different stages of their lives in order to survive. The first things infants need to do is to be able to feed, so their gross-motor functions would be tuned to that behavior. Then, they need to be able to track visual items, grasp objects, and learn balance so they can walk. Since the first few months of life are centered around eating and survival skills, the brain is also developing and using the nutrition from mother's milk (or substitute) to build brain function that allows for further development as the child ages. The infant does not need to grasp tightly or walk in the first few months after birth -- instead, it needs to feed and develop. Only when those basic functions are complete does the brain kick in for further development (Kalat, pp 124-5).

Part 3 - Haloperidol is a drug that blocks dopamine synapses. What effect would it be likely to have in someone suffering from Parkinson's disease?

Dopamine is an organic chemical that is a neurotransmitter and hormone. It is responsible for a number of neurological functions: reward-driven learning, motor function, voluntary movement, cognition, and mood. Parkinson's disease is an age-related degenerative condition that causes tremors, motor impairment, and lack of the individual's ability to control which muscles react to stimuli. Scientists believe that Parkinson's is caused by the loss of dopamine-secreting neurons in a part of the brain called the substantia nigra. This is an area of the midbrain that plays an important role in addiction, reward, and movement. If a Parkinson's patient already has a loss of dopamine, then the use of haloperidol would have a negative effect, likely increasing the symptoms of the disease (Kalat, p. 261).