Why do modern-day humans have a seemingly in-built ability to learn highly complex procedures, which our ancestors, just a few hundred generations ago, would have never needed?

The neuronal recycling hypothesis was developed in the early 2000s as an attempt to explain the so-called 'reading paradox' (ref.)

Many research groups* ^{see note} maintain that a brain region called the Visual Word Form Area (VWFA) located in the left lateral occipitotemporal sulcus, is heavily involved in the process of reading. But the 'technology' of writing and reading has only existed for a few thousand years, seemingly far too short a period for a 'purpose built' brain area to have evolved through evolution over generations.

The neuronal recycling hypothesis suggests that the brain area was 're-purposed', to enable reading by a process of 're-wiring' of previously-existing neural networks which had some other function(s) in the past. In other words, that brain networks are highly 'plastic'.

That's to say that there is no need for the development of entirely new brain areas to deal with new and substantial social changes, because older pre-existing areas ares can be 're-wired'.

This raises several unanswered questions, for example :

[1] What was the original purpose(s) of the existing brain area(s)?

[2] How is the re-purposing achieved so rapidly?

[3] What other brain networks are potentially re-wireable?

[4] If entire brain areas can be requisitioned so readily, why haven't other species been able to deal with complex new procedures by neuronal recycling?

Many other current-day skills might fit with the hypothesis. For example mathematical abilities, complex musical abilities, computer / tech. literacy etc. etc.

Note : * Not all research groups are convinced about the VWFA, see The myth of the visual word form area NeuroImage, Volume 19, Issue 3, pp. 473-481