Final answer:
The recent changes in Yanomami tribal society are due to gold miners and cattle ranchers invading their land, causing environmental damage, introducing diseases, and leading to violent conflicts.
Step-by-step explanation:
The changes in Yanomami tribal society in recent times can be primarily attributed to the encroachment of outsiders, such as gold miners and cattle ranchers, onto their territory. These groups not only invade land but also bring about violence, environmental devastation, and diseases. Much like the effects seen in other indigenous societies, such as the Kayapó, these incursions by foreign entities bring widespread disruption to the traditional ways of life, negatively impacting the health, economy, and culture of the Yanomami people.