You Know What They Say About Whales With Big Pelvic Bones

[Buster's Uncle]

You Know What They Say About Whales With Big Pelvic Bones
Takepart.com
By Taylor Hill | 4 hours ago



Like our tailbones, whale and dolphin pelvic bones have long been thought of as useless evolutionary leftovers from the marine mammals’ land-roaming days, when they had legs.

But the latest research from the Natural History Museum of Los Angeles and the University of Southern California shows that the hip bones could be integral to the dolphins and whales sex lives.

“Everyone’s always assumed that if you gave whales and dolphins a few more million years of evolution, the pelvic bones would disappear,” said Matthew Dean, an assistant professor at USC and co-author of the study. “But it appears that’s not the case.”

“Whale pelvic bones were thought by many evolutionary biologists to be non-functional, but our study overturns this idea,” Dean said.

The reason for scientists’ previous dismissal of the pelvis? It didn’t connect to any other bone in the marine mammals’ bodies, floating independently from the rest of the whale skeleton.

But after digging through thousands of boxes of dolphin and whale bones stored at the Natural History Museum and the Smithsonian Institute, Dean and co-author Jim Dines of the Natural History Museum found that the muscles that control the penis attach directly to the pelvic bone, giving the animals an ability to control the organ.

And the friskier the whale and dolphin—those species associated with having multiple mating partners—the larger the animal’s sexual organ tends to be.

And it all could come down to pelvic bone size.

Dean explained it like this: The more promiscuous species of whales and dolphins have evolved longer penises than their monogamous counterparts, which scientists hypothesize gives them an evolutionary advantage in mating. But those longer organs require larger muscles to maneuver it, and those larger muscles need a bigger pelvic bone to anchor to.

But does size really matter? Dean couldn’t say for sure.

"We probably will never know because whales and dolphins are a horrible experimental system,” Dean said. “In order to answer the question, we'd have to bring them in the lab and experimentally manipulate them —of course that is impossible.”

But one thing the study does seem to show is that pelvic bones in whales aren’t going away any time soon.

Aside from the dwarf sperm whale, which has evolved cartilage to replace its pelvic bones, all species of whales and dolphins still have their hip bones intact, Dean said.

“The fact that all species still have them suggests they are being maintained by selection,” he said.


http://news.yahoo.com/know-whales-big-pelvic-bones-151247502.html