Penguins have no external genitalia. Even as adults, the males and females can be difficult to tell apart.
It’s safe to say that human intimacy, at its best, surpasses that of any animal, even the most intelligent.
A memory of past events helps a cell learn how to respond to recurring threats and protect the genome.
What amazes me is how the female butterflies can smell dill over great distances, and so deposit their eggs on the right plants.
Does a turtle swim ashore and lay eggs, or to lay eggs?