In a group setting, one member could take advantage of the that he/she receives from the other group members, thereby exploiting the reciprocity norm to his/her advantage.
some researchers believe that instead evolved.

a. gratitude
b. diffusion of responsibility
c. bystander effect
d. volunteering

a. gratitude

Explanation: According to researchers

Reciprocity is defined as the exchange of goods or services out of one's kindness to another. This mutual and friendship exchange of goods and services has improved the species survival according to researchers. Robert Trivers, who is the originator of the theory of reciprocal altruism states that gratitude is born through these act of mutual kindness.

Other researchers suggest that gratitude is what drives us to act back and return the act of kindness where we have received it,it drives us to show our appreciation.

This act of gratitude is what encourages the other person to actual do us favors again.

So according to researchers reciprocity is what drove the evolution of gratitude.

the period of human evolution has coincided with environmental change, including ('hominin' refers to any bipedal species closely related to humans – that is, on how do we know earth's climate has changed? a map showing dates and locations of prehistoric archeological sites and migration routes from africa into.

south, because if you took a map you would see texas is directly in the middle of east and west, but it is also downwards towards mexico, therefore it is south