Final answer:
Homo sapiens first appeared around 200,000 years ago, based on the widely supported 'out of Africa' model. Ongoing research, including genetic analysis and fossil evidence, like the findings in Morocco, consistently refines this estimate and our understanding of human evolution.
Step-by-step explanation:
In the evolutionary history of Earth, Homo sapiens probably first appeared approximately 200,000 years ago.
An explanation for this timeline is based on the "out of Africa" model, which posits that modern humans emerged in Africa around 200,000 years ago. Subsequently, about 100,000 years ago, they began expanding out of Africa, replacing other human species. This model is supported by evidence from both fossil records and genetic analysis. Another theory, the "multiregional evolution model", suggests that Homo sapiens evolved from Homo erectus in various regions simultaneously, primarily based on fossil evidence. However, the genetic evidence favors the "out of Africa" model. This model is critical in understanding the progression and spread of modern humans across different continents.
Additionally, archeological findings, such as those in Morocco dating back to roughly 300,000 years ago, have identified specimens biologically identical to contemporary Homo sapiens, thus continually informing and refining our understanding of human evolution. Through the use of sophisticated tools, mastery over fire, and adaptations like clothing and shelter, Homo sapiens thrived and survived various climatic conditions across the globe.