According to the triune brain concept, what is the evolutionary explanation for why the limbic system developed early in mammals?

The Triune Brain concept, proposed by neuroscientist Paul D. MacLean, suggests that the human brain is actually three brains in one: the reptilian complex, the limbic system, and the neocortex. Each of these "brains" corresponds to a different stage in our evolutionary history.

The limbic system, which includes structures such as the hippocampus and amygdala, developed early in mammals for several reasons:

1. Survival Needs: The limbic system is primarily responsible for our emotional life and has a lot to do with the formation of memories. In the early stages of mammalian evolution, the ability to remember locations of food and danger (emotional memories) would have been crucial for survival.

2. Social Cohesion: The limbic system also plays a significant role in social behaviors, which are critical for the survival of mammals. Early mammals needed to cooperate in packs to hunt and protect each other. The limbic system helped them form these necessary social bonds.

3. Reproduction: The limbic system is involved in mating behaviors, which are obviously important for the continuation of the species.

In summary, the limbic system developed early in mammals because it played a crucial role in survival, social interaction, and reproduction.