https://news.sky.com/story/woman-with-d ... s-12414954
https://en.wikipedia.org/wiki/Down_syndrome#History
There are some conditions modern toxins and ecological disruptions are not responsible for. This is our evolutionary history and you need to start paying attention. You think our brains just happened to get bigger? There are skulls with cranial capacity near a hundred cubic centimetres large than so called civilised craniums.
https://en.wikipedia.org/wiki/Microcephaly#History
People with small heads were displayed as a public spectacle in ancient Rome.[66]
People with microcephaly were sometimes sold to freak shows in North America and Europe in the 19th and early 20th centuries, where they were known by the name "pinheads". Many of them were presented as different species (e.g., "monkey man") and described as being the missing link.