The Cognitive Load Theory, or CLT, (Van Gerven et. al., 2003) is a philosophical framework that states that the working memory in our brain has a specific capacity for absorption and retention of information.
Several concepts stem from the CLT such as "saturation", "cognitive capacity"," recursion", "transfer" and "cognitive load". Cognitive capacity is defined as the extent to which the brain is able to "digest" and keep new and old information during a specific task, or in a specific time frame, until it is time to put it into use (which would be the actual cognitive load). In theory, there are limitations as to how our working memory is best put to use. Hence,the implication for educators everywhere is that, in order to sustain the attention of the students for them to remember what they learn, the teacher must make sure that the information is presented in a way that catches their attention and keeps them interested throughout a lesson. Also, huge amounts of information in one lesson is an educational malpractice; instead, small amounts of important facts that can be made into relevant connections is what works best.
As to the relevance of cognitive capacity to human evolution, the least-researched answer that can be given in such as small forum as is this one would be that current paleoanthropological researchers are currently making use of early stone tools made by our early hominid ancestors to determine how the jump in cognitive capacity occurred from one evolutionary era to another. Scientists are certain that artifacts from the Stone Age have the answers to every question regarding our cognitive development because it shows that these early hominids suddenly became passive and able to examine stones, make correlations as to their usage, and apply skills with the information that they gathered from their observations. This makes the potential call that neuroplasticity seems to have been the causative factor for this sudden change in cognitive skill. The relevance to human evolution is that cognitive skill is what mainly differentiates us from the non-human primate and what ultimately gave us basic survival skills, problem solving abilities, and the power to transform the world to the way that we know it today.