The nanodiamonds found at the Younger Dryas boundary are nearly identical to those from the KT impact 66 million years ago. The difference? The Younger Dryas event wasn't quite as catastrophic, because if it had been, we wouldn't be here to discuss it. But modern humans were alive during this period, witnessing whatever happened. The evidence suggests a cosmic impact event powerful enough to leave the same signature as the dinosaur extinction, just not quite at the same scale. If you were living near the impact zone, survival would have been impossible. The fact that humanity survived at all tells us something important: the event was catastrophic enough to leave a global marker layer, but localized enough that populations in other regions endured. That narrow margin between extinction and survival is written in the geological record, and it raises serious questions about how close we came to not making it through.