Complex sentence: In 1972 Shurley wrote that he could not definitely determine the cause of these, but largely from the latter eventually concluded she had been retarded from birth, as significantly elevated numbers of sleep spindles are a phenomenon typically found in people born with severe retardation.
Split into simpler sentences: In 1972 Shurley wrote that he could not definitely determine the cause of these. Eventually, however, largely from the latter he concluded she had been retarded from birth, as significantly elevated numbers of sleep spindles are a phenomenon typically found in people born with severe retardation.