Unlike many modern murder mysteries, the one that occurred about 180,000 years ago didn’t take place on a dark and stormy night. It probably began on a pleasant autumn afternoon, the fourth or fifth sunny day in a warm spell covering temperate northern Europe.
KILLER CLUE. This fossilized 20-micrometer-diameter cyst of a microbe that often lives with deadly cyanobacteria suggests the presence of the potent toxin producer.
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