The lecturer talks about the altruism of animals and human beings from a different aspect and gives the scientifc explanation on thoses old assumptions with the two examples.
First of all,some animals don't sacrifice themselves for their mates. The sentinel meerkat eats before it stands on guard. So even though the other meerkats have food to eat, sentinel meerkat will not starve itself. Moreover, when they are in danger, sentinel meerkat issues an alarm and runs away first while the others receive the signal which means either gathering or moving away. In this sense, they are in greater danger. Therefore, the lecture contradicts with the reading on this opinion.
Then, speaking of human beings, people don't solely perform altruistic acts while gain nothing for themselves. The example of donating one's kidney to others doesn't seem that the donator gets little reward. It is quite possible that he receives the appreciation of the receiver as well as the whole society. And he himself sees his worth. One this aspect, human beings peform altruism while receive praise from the society.