What are ghost lineages, remnants of the past that still exist in our DNA today?

This reconstruction is based on the Harbin skull from China. Scientists now recognize the Harbin skull as that of a Denisovan who lived about 146,000 years ago. Genetic analyses show the Denisovans encountered and interbred with the superarchaic human ghost lineage during two distinct periods. Ghost lineages reveal themselves through ancient genes that still exist in living beings today.

Ghost lineages reveal themselves through ancient genes that still exist in living beings today.