Influence of Maternal Age on Child Gender Ratios

Whether you love spiders or can't be within 10 feet of them, you probably think of them crawling around on land. Historically, most researchers would probably say the same thing: Based on the fossil record, they've thought the earliest arachnid ancestors existed around 450 million years ago, living and diversifying exclusively on land. But a new study out this week in the journal Current Biology suggests arachnid brains may have originated much earlier in the ocean.

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