Given the background: Human beings invented agriculture about 10,000 years ago. This provided a bigger, more dependable food supply. It also allowed people to settle down in villages and cities for the first time. Birth rates went up because there was more food and settled life had other advantages. Death rates also rose because of crowded living conditions and diseases that spread from domestic animals. Because the higher birth rates were matched by higher death rates, the human population continued to grow very slowly. and the situation: David was studying human history. He selected two specific eras of human history, era A and era B. Era A was before humans had invented agriculture. And, era B was after the invention of agriculture. He noticed that human societies had changed dramatically after the invention of agriculture. Answer the following question: Which era saw lower death rate, era A or era B?
----
Answer: era A

Given the background: Reptiles are a class of animals comprising turtles, tuataras, lizards, snakes and crocodiles. They are tetrapods, but the snakes and a few species of lizard either have no limbs or their limbs are much reduced in size. Their bones are better ossified and their skeletons stronger than those of amphibians. The teeth are conical and mostly uniform in size. The surface cells of the epidermis are modified into horny scales which create a waterproof layer. Reptiles are unable to use their skin for respiration as do amphibians and have a more efficient respiratory system drawing air into their lungs by expanding their chest walls. The heart resembles that of the amphibian but there is a septum which more completely separates the oxygenated and deoxygenated bloodstreams. The reproductive system has evolved for internal fertilization, with a copulatory organ present in most species. The eggs are surrounded by amniotic membranes which prevents them from drying out and are laid on land, or develop internally in some species. The bladder is small as nitrogenous waste is excreted as uric acid.Turtles are notable for their protective shells. They have an inflexible trunk encased in a horny carapace above and a plastron below. These are formed from bony plates embedded in the dermis which are overlain by horny ones and are partially fused with the ribs and spine. The neck is long and flexible and the head and the legs can be drawn back inside the shell. Turtles are vegetarians and the typical reptile teeth have been replaced by sharp, horny plates. In aquatic species, the front legs are modified into flippers.Tuataras superficially resemble lizards but the lineages diverged in the Triassic period. There is one living species, Sphenodon punctatus. The skull has two openings (fenestrae) on either side and the jaw is rigidly attached to the skull. There is one row of teeth in the lower jaw and this fits between the two rows in the upper jaw when the animal chews. The teeth are merely projections of bony material from the jaw... and the situation: Two continents were known for the strange discrepancies in animal populations. Asia was mostly populated by reptiles of all species, while Africa was mostly populated by birds and very few reptiles. Answer the following question: Which continent was inhabited by fewer turtles?
----
Answer: Africa

Given the background: A dilution effect is seen when animals living in a group "dilute" their risk of attack, each individual being just one of many in the group. George C. Williams and W.D. Hamilton proposed that group living evolved because it provides benefits to the individual rather than to the group as a whole, which becomes more conspicuous as it becomes larger. One common example is the shoaling of fish. Experiments provide direct evidence for the decrease in individual attack rate seen with group living, for example in Camargue horses in Southern France. The horse-fly often attacks these horses, sucking blood and carrying diseases. When the flies are most numerous, the horses gather in large groups, and individuals are indeed attacked less frequently. Water striders are insects that live on the surface of fresh water, and are attacked from beneath by predatory fish. Experiments varying the group size of the water striders showed that the attack rate per individual water strider decreases as group size increases. and the situation: Kenya's Masai Mara wildebeest migration is one of the greatest spectacles in the natural world. Every year thousands of wildebeests cross the Mara river. John went to see the migration last year. He noticed that the wildebeests crossed the the river in a very large group. He noted that as case A. His guide told him that is not the case in other times of the year. The wildebeests cross the river in smaller groups in other times. John noted that as case B. The guide added that in both cases on thing is constant, they are attacked by the lions. Answer the following question: In case B, would an individual wildebeest get less or more benfit than in case A?
----
Answer:
less