These four events repeat every 'tropical' year (365 days, 5 hours, 49 minutes), so they become later by about six hours, or (if there has been an intervening leap day) earlier by about 18 hours, from one year to the next.
The three distinctive signs and symptoms of autism include problems with verbal and nonverbal communication, difficulties with social interaction, and repetitive behaviors or narrow, obsessive interests. There are three distinctive symptoms of autism.
In fact, an early sign of autism is a delay or even a total lack of development of spoken language skills. Autism is considered to be a spectrum disorder which means it consists of a wide range or spectrum of disorders involving impaired communication and social interaction skills.