This is nonsense. There are no 70%+ mass extinctions ever 12k years. It is beyond bullshit. The mass global extinctions are on a 50+ million year cycles and there are MANY overlapping cycles at that (something like 12 suspected or so). Every 12k to 36k we have substantial changes related to the earths procession but that is barely noticeable globally. There are many out of band events that could affect species that are high on the predator / specialization scale such as supervolcanoes. The yellowstone supervolcano has a period of about 250 000 years of activity, we are way overdue by a huge amount of years already and the last time that it errupted it covered north america in ash a few inches thick down to Florida. That type of even certainly would affect top / hyperspecialized predators like our selves especially when there were only millions of us on the planet, but no record exists that suggests that even supervolcanoes like yellowstone that can cover an entire continent in ash could create 70% extinction globally. The most likely out of band events to take us out would be either asteroid impacts of desease. None of the cyclical patterns you speak of matter in the least beyond perhaps being civilization resetting as it is speculated that whatever Atlantis was it got wiped out during the younger dreias around 12k years ago. Speculation is a good start, but you need to keep on reading, digging and thinking critically as you dig through the information.