Chapter 1: The Limiting Factor For Brain Growth In Evolution

Evolution does not follow a straight path, it occurs in fits and spurts. During the 2 million years of existence, the homo genus experienced prolonged periods of little change, but then during others, our ancestors underwent significant changes. There was a period of time when changes in the climate and geography, caused our ancestor's diet to change. This change in diet introduced high quantities of a single molecule, docosahexaenoic acid (DHA), that is the limiting factor in human brain growth. This chapter examines how a single molecule was able to cause a dramatic increase in the size of our brains, shaping evolution and altering the course of history.

As our brains began to grow in capacity and complexity, we began to development new skills. The application of the increased brain power to the traits communication, hunting, and survival, have allowed us to become the humans we are now. Through exaptation, we have co-opted the increase in brain size, for an increase in the very traits that make us intelligent.

In this chapter, we explore how the more commonly known "Savanna Hypothesis" of human development is flawed and that in fact, the evidence points to humans living in close proximity to lakes, rivers, oceans, and other marine ecosystems. With a diet consisting of high amounts of fish and in turn, high amounts of DHA, the brains of our ancestors were able to grow so large that we have the highest encephalization quotient of any animal.

Book: Human Brain Evolution : The Influence of Freshwater and Marine Food Resources

Papers:

Evidence for the unique function of docosahexaenoic acid during the evolution of the modern hominid brain.

Docosahexaenoic acid and human brain development: evidence that a dietary supply is needed for optimal development.

Long-chain omega-3 fatty acids and the brain: a review of the independent and shared effects of EPA, DPA and DHA

The early development and evolution of the human brain.