From UPSC perspective, the following things are important :
Prelims level : Mitochondrial DNA
Mains level : Evolution of modern man
- A recent paper in the prestigious journal Nature claims to show that modern humans originated about 200,000 years ago in the region around northern Botswana.
About the study
- The scientists studied genetic data from many individuals from the KhoeSan peoples of southern Africa, who are thought to live where their ancestors have lived for hundreds of thousands of years.
- The researchers used their new data together with existing information about people all around the world to reconstruct in detail the branching of the human family tree.
- Mitochondrial DNA is the small circular chromosome found inside mitochondria.
- These organelles found in cells have often been called the powerhouse of the cell.
- The mitochondria, and thus mitochondrial DNA, are passed almost exclusively from mother to offspring through the egg cell.
- The study focused just on mitochondrial DNA. This means it isn’t mixed up with DNA from fathers and so is easier to track across the generations.
- The new study doesn’t tell about the origin of the human genome but the place and time where our mitochondrial DNA appeared.
Why Mitochondrial DNA was studied?
- The fact that mitochondrial DNA comes almost only ever from mothers also means the story of its inheritance is much simpler than the histories of other genes.
- This implies that every bit of our genetic material may have a different origin, and have followed a different path to get to us.