Final answer:
The 1987 Berkley study of mitochondrial DNA revealed that all humans shared a common ancestor who lived in Africa about 200,000 years ago. It also identified the Denisovans, a human subspecies.
Step-by-step explanation:
The 1987 Berkley study of mitochondrial DNA revealed that all humans shared common ancestors who lived in Africa about 200,000 years ago. By analyzing mutations in mtDNA, researchers were able to trace our ancestry back to one female, often referred to as Mitochondrial Eve, who lived in Africa around that time. This study also identified the Denisovans, a human subspecies, through differences in their mitochondrial DNA compared to modern humans and Neanderthals.