How have social categories, roles, and practices have changed since 1900?

There have been many different social hierarchies over the ages. In India there was the caste system which came from traditional Hindu beliefs. They believed that it was impossible to change your caste and you job and role in society was based off of your caste and Jati which was a section within the caste. In Sparta, the soldiers were at the top right under the generals and elders. This was because of the importance and value placed on the military and fighting men. At the beginning of the founding of Sparta, there was a slave revolt and the Spartans vowed it would never happen again, so they took their military to the next level so that the slaves could never revolt again.

Explanation:

the indirect evidence that supports that the bubbles so generated are oxygen is that the bubbles in the plant increases when it moves towards the brighter light.