What caused humans to become the top species on earth, and why is there such an intellectual gap between humans and all other species?
In: Earth Science
Intelligence is expensive.
Having a well developed brain costs a lot of energy, and – for generational improvement – requires a lot of parental nurturing. That means you can only develop it in settings where there is ample energy, and a very useful trait is having sufficiently cohesive social structures to support the parenting, teaching, and development of the young, as well as having enough free time to develop skills and technology which apply that intelligence.
That requires a number of other traits to develop beforehand or alongside. For us there were several imporotant developments, which included (but certainly wwere not limited to):
1. Fine motor skills and physical strength to enable tool use
2. Access to higher energy foods. This was done through the control of fire, and the development of agriculture (or at least communal hunter-gathering, allowing some individuals to not need to be out exposed to the environment to feed themselves). Both are dependent on number 1.
3. Having a sufficiently cohesive social order that you can dedicate some individuals to specific tasks, while freeing up others to experiment with supporting young, developing new skills, passing those skills on to others, and so on. That is facilitated by the development of complex language (and hence feeds back into benefits of greater intelligence, and so on)
4. The physiology to allow development of larger brain cavities – birthing something with a massive head is a physiological challenge, and the fragility and skeletal requirements are not insignificant. Young gazelle and impala (and their mothers) can run within minutes of being born. They are much better addapted to surviving around lions than we are.
The costs in developing intelligence are very high, but once you have an edge the impact snowballs – it becomes a positive feedback loop where the intelligence allows further refining and honing of the environment to allow further developments.
You can’t look on intelligence as a single element that is beneficial on its own; it’s not. You have to have other complimentary physical, social and environmental conditions that allow it to flourish. In a sufficiently aggressive or hostile environment intelligence becomes a burden, because immediate survival of the young to the point where they can reproduce becomes the primary driver, and the nurturing required for the other elements that fed into the development of intelligence across a species get missed out.
I’m sure there’s some evolutionary biologists around who can refine this with better info, but this is the broad picture (at least as I understand it).
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