Final answer:
The MMR hypothesis suggests a link between the MMR vaccine and autism, but multiple studies have debunked this claim. The belief in the MMR hypothesis was caused by a now-retracted study by Andrew Wakefield in 1998.
Step-by-step explanation:
The MMR hypothesis, also known as the measles, mumps, and rubella hypothesis, suggests a link between the MMR vaccine and the development of autism. However, this hypothesis has been thoroughly investigated and multiple studies have shown no evidence to support this claim. The belief in the MMR hypothesis was largely caused by a now-retracted study by Andrew Wakefield in 1998, which falsely claimed a connection between the MMR vaccine and autism. This study and subsequent investigations found significant flaws in Wakefield's research and the study was retracted due to ethical concerns and lack of scientific validity.