Ed Yong profiles a group of animals called bdelloid rotifers. The have evolved asexually for between 40 and 100 million years:

They live in an all-female world in which mothers give birth to daughters who are genetically identical clones. No males have ever been found. Many animals, including aphids, sharks and Komodo dragons, can reproduce asexually from time to time but sex is still their default setting... Bdelloids are the tiniest twigs on a tree of life that is otherwise dominated by sex.

What would Aquinas make of that?

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