1st becoz homo spiens fossilis (cro magnon man) was extinct modern man who lived in Africa Nd got evolved into modern man homo sapiens sapiens so obviously variation should be done greater in African man not in asian homo erectus man

Introduction:
The debate about the origin of modern humans has long been a topic of interest and study in the field of anthropology. Two opposing views suggest either Homo erectus in Asia or an African origin as the ancestors of modern humans. An examination of DNA variations can provide valuable insights into this debate.

Explanation:
To determine the origin of modern humans based on DNA variations, we need to analyze the genetic diversity in different populations. The level of genetic variation within a population can provide clues about the length of time that population has been evolving separately, as well as their ancestral relationships.

A) Greater variation in Africa than in Asia:
If there is a greater variation in DNA within African populations compared to Asian populations, it suggests that modern humans originated in Africa. This is because Africa is considered the ancestral homeland of all modern humans, and as populations migrated out of Africa, they carried only a subset of the genetic diversity present in their African ancestors.

- Genetic diversity: African populations exhibit higher levels of genetic diversity compared to populations in other regions. This is due to the fact that humans have been living in Africa for a longer period of time, allowing for more genetic mutations and variations to accumulate.
- Coalescence theory: The coalescence theory suggests that all modern human genetic lineages can be traced back to a single common ancestor in Africa. Therefore, the higher genetic diversity in Africa supports the hypothesis of an African origin for modern humans.
- Out of Africa migration: The "Out of Africa" migration theory proposes that modern humans originated in Africa and then migrated to other parts of the world. If African populations have greater genetic diversity, it indicates that they have been evolving for a longer period of time, reinforcing the idea of an African origin for modern humans.

B) Greater variation in Asia than Africa:
If there were greater DNA variation within Asian populations compared to African populations, it would contradict the hypothesis of an African origin for modern humans. However, this scenario is less likely based on the existing body of genetic evidence.

- Genetic bottleneck: If Asian populations had greater genetic diversity, it would imply that they had been evolving separately for a longer time than African populations. This contradicts the genetic bottleneck theory, which suggests that during the migration out of Africa, only a small subset of genetic diversity was carried by the migrating populations.
- Migration patterns: The genetic evidence, including mitochondrial DNA studies and Y-chromosome analysis, consistently supports an African origin for modern humans. These studies have shown that the oldest and most diverse human lineages are found in Africa, providing strong evidence for an African origin.

Conclusion:
Based on the current scientific understanding, the observation of greater DNA variation within African populations compared to Asian populations supports the hypothesis of an African origin for modern humans. The higher genetic diversity in Africa can be explained by the longer period of time humans have inhabited the continent, the coalescence theory, and the evidence from genetic studies supporting an African origin.