I1 was formed around 27,500 years ago when it split apart from I2 yet the most recent common ancestor for all modern I1 individuals is around 4,600 years ago. Between 27,500 and 4,600 intermediate branches of pre-modern I1 spread all over Europe. They carry some but not all of these 312 SNPs. Some of these ancient intermediate branches can be found from Hungary to Spain. All of these intermediate branches became extinct except for one individual who is the common ancestor to all modern I1 individuals alive today who in my opinion lived in Scandinavia around 4,600 years ago. The “bottleneck” refers to all of these other branches dying off except for him. There are at least 312 SNPs associated with this individual that he inherited from all his patrilineal ancestors since they branched apart from I2 27,500 years ago. I also think that Mr. I-DF29 who lived shortly after this I1 ancestor ( I don’t call him Mr. I-M253 because we have no idea about the chronological order of those 312 SNPs associated with him) could be considered a bottleneck as well since 99% of all modern living I1 are positive for the subclade of I-DF29.