I recently learned that human brain size has been decreasing for the last 10,000 years.[0]

The thinking is that prior to us building societies, we all had to be generalists and know "everything." Once we are in a group, we can offload some knowledge to others in the society.

My point being, this all seems to have started long ago and doesn't even necessarily require technology to explain the beginnings of the trend.

[0] https://www.dwarkesh.com/i/158922207/why-is-human-brain-size...