There's a Live Science headline today that reads "Mystery Solved: Why Gorillas Eat Rotting Wood." I have to be honest that I didn't realize this was something scientists had been trying to figure out, but it is pretty interesting. According to the article:

Gorillas in the Bwindi Impenetrable National Park in Uganda will suck on wood chips for several minutes before spitting them. Sometimes they chew on them until their gums bleed. They have also been seen licking the bases of tree stumps and the insides of decayed logs, and breaking off pieces of wood to munch on later. Gorillas will return daily to the same stump and take turns feeding.

Researchers previously thought there may be some mysterious medicinal benefit the gorillas received from the wood but it turns out they just craved the sodium.

The researchers analyzed these items for their sodium content and found that the decayed wood was the source of over 95 percent of the animal's dietary sodium, even though it represented only about 4 percent of their wet weight food intake.

I've always been amazed that even though animals may not know that they're adding more sodium (or any other valuable nutrients) to their diet, they find and crave the nutrients they need and develop eating habits over time through a process of trial and error. As the article mentions, we see this with plenty of other animals, such as elephants traveling to underground caves for the salt deposits there. Which reminds me, in a childbirth class my wife and I recently took, a few of the women in the class talked about craving avacados. It makes me wonder if they were desiring them because of the high levels of fat they needed. And no, I'm not comparing pregnant women to gorillas.