Toefl Task

The passages explain the concept of Altruism and gives examples about how animals, including people can be altruistic. The lecture, on the other way hand, take a look with a bit more details into the examples of the passage, to prove that they are not as altruistic as the passage says.
First the professor explains that when a group of meerkats are hunting for food, or even already eating, they always have a member of the group acting as a sentinel and looking for predators. But the sentinels are usually the first ones to eat, because they ate before the guard started. So they are not starving themselves for the benefit of the group. Also, since they are the first ones to see the predator, they have more chances to escape than the others that are distracted doing another thing.
The professor adds to the theory by showing that human beings acts on the exactly the same way. Even in a very extreme example, like when someone offers to donate an body organ to a family member or to a stranger. This person might not gain any material reward, but they can gain another desirable things ["another" is singular, but "things" is plural. You should probably fix this]. Many people feel very complete and satisfied with themselves when they help other people. Besides, they will get the appreciation of the society as well.
Concluding, the professor shows that none of the examples that were given in the passage were completely altruistic, because in on some level it they did provided rewards.