Editing Evolutionary neuroscience (section)

== Evolution of brains ==
Many of Earth's early years were filled with brainless creatures, and among them was the [[Lancelet|amphioxus]], which can be traced as far back as 550&nbsp;million years ago. Amphioxi had a significantly simpler way of life, which made it not necessary for them to have a brain. To replace its absence of a brain, the prehistoric amphioxi had a limited [[nervous system]], which was composed of only a bunch of cells. These cells optimized their uses because many of the cells for sensing intertwined with the cells used for its very simple system for moving, which allowed it to propel itself through bodies of water and react without much processing while the cells remaining were used for the detection of light to account to the fact that it had no eyes. It also did not need a sense of hearing. Even though the amphioxi had limited senses, they did not need them to survive efficiently, as their life was mainly dedicated to sitting on the seafloor to eat.<ref name=Barrett-2020><br/>{{cite book |last=Barrett |first=L.F. |author-link=Lisa Feldman Barrett |date=17 November 2020 |title=Seven and a Half Lessons about the Brain |publisher=Houghton Mifflin Harcourt |isbn=9780358157144 |location=New York, NY }}</ref>{{rp|style=ama|pp= 1–2}} Although the amphioxus' "brain" might seem severely underdeveloped compared to their human counterparts, it was set well for its respective environment, which has allowed it to prosper for millions of years.

Although many scientists once assumed that the brain evolved to achieve an ability to think, such a view is today considered a great misconception. 500&nbsp;million years ago, the Earth entered into the [[Cambrian|Cambrian period]], where hunting became a new concern for survival in an animal's environment. At this point, animals became sensitive to the presence of another, which could serve as food. Although hunting did not inherently require a brain, it was one of the main steps that pushed the development of one, as organisms progressed to develop advanced sensory systems.<ref name=Barrett-2020/>{{rp|style=ama|pp= 2, 4–5}}

In response to progressively complicated surroundings, where competition between animals with brains started to arise for survival, animals had to learn to manage their energy.<ref name=Barrett-2020/>{{rp|style=ama|pp= 5–6}} As creatures acquired a variety of senses for perception, animals progressed to develop [[allostasis]], which played the role of an early brain by forcing the body to gather past experiences to improve prediction. Since prediction beat reaction, organisms who planned their manoeuvres were more likely to survive than those who did not. This came with equally managing energy adequately, which nature favoured. Animals that had not developed allostasis would be at a disadvantage for their purpose of exploration, foraging and reproduction, as death was a higher risk factor.<ref name=Barrett-2020/>{{rp|style=ama|pp= 7–8}}

As allostasis continued to develop in animals, their bodies equally continuously evolved in size and complexity. They progressively started to develop [[Circulatory system|cardiovascular systems]], [[respiratory system]]s and [[immune system]]s to survive in their environments, which required bodies to have something more complex than the limited quality of cells to regulate themselves. This encouraged the nervous systems of many creatures to develop into a brain, which was sizeable and strikingly similar to how most animal brains look today.<ref name=Barrett-2020/>{{rp|style=ama|pp= 9–10}}