Viruses increase the size of DNA in some cases and if the cell is a gamete then this increase in size is inherited. Down syndrome and its equivalents in other species do the same.
Ok so is a person with down syndrome better equiped to survive?
...all species. Additionally there are other processes which work on a more granular scale instead of duplicating the whole chromosome: http://tinyurl.com/yayeuk5r
No. I never said that. I said that there are many processes which can make space for more info in the DNA. While this specific process causes DS to humans, it's not always bad for...