Fossilized Bear Penis Bones Solve Eternal Mystery of Ancient Bear Sex

If you possess even a glimmer of innate curiosity and reverence for the natural world, you likely spend a lot of time wondering what sex was like for prehistoric bears. “Yes, I know modern bear intercourse looks like,” you probably think as you futilely court sleep in the wan hours before dawn, “But what about those extinct ursids that once roamed the plains of Spain?”

Thankfully, paleobiologists have just solved that enigma. A group of researchers recently unearthed a treasure trove of ancient bear penis bones, also known as bacula. Interestingly, bacula are difficult to find in the fossil record because they’re easily broken and also often mistaken for ribs, which is a fact I haven’t finished processing yet.

The bacula in question belong to a large primitive bear, known by its friends and penis-bone-enthusiasts as Indarctos arctoides. This bear species roamed the Earth 12 – 5 million years ago, and it was similar in size to the European brown bear in all ways — save for one (can you guess which?) (It’s penis bone size, guys. That’s what it is.). The extinct bear’s baculum was, on average, 9.1 inches long. For reference, polar bears, which are nearly twice as big, only have an average of 7.3 penis inches to their name.

What can we infer from this? A lot more than you’d expect. According to Live Science:

Based on the size of baculum, the researchers think the bear likely had fewer but longer periods of intercourse than other mammals. A long baculum, the study researchers say, could have served as a physical support during mating, helping to keep the female’s reproductive tract open and in an optimal position for fertilization during these sporadic dalliances.

Indarctos arctoides may have had lower population densities, causing this infrequent intercourse. Which is really sad, if you think about it — all those cute lil’ bears roaming around with no one to keep them company but their own oversized bear genitals.

The researchers also posit that female bears may have used the size of the males’ mem-bears (copyright Callie Beusman 2013) to judge whether or not they would do intercourse with them. Way harsh. No ancient Spanish bear had a nonjudgmental dick pic rating blog, it would seem.

“Penis Bones Show Size Mattered to Ancient Bear” [Live Science]
Image via Tony Campbell/ Shutterstock.