Commonly held presumptions about what constitutes evidence for evolution as a viable explanation for the bio-diversity we see will have to be rethought. All too often, defenders of the evolutionary process point to what they consider examples of homology, or the science of things kinda looking like other things in other animals. Well, the idea that dolphins and whales “hip bones” which are merely a bygone leftover from land-walking days has just come into question with new research out of the University of Southern California and Natural History Museum of Los Angeles County.
(Science Daily) — Both whales and dolphins have pelvic (hip) bones, evolutionary remnants from when their ancestors walked on land more than 40 million years ago. Common wisdom has long held that those bones are simply vestigial, slowly withering away like tailbones on humans.New research from USC and the Natural History Museum of Los Angeles County (NHM) flies directly in the face of that assumption, finding that not only do those pelvic bones serve a purpose — but their size and possibly shape are influenced by the forces of sexual selection.
“Everyone’s always assumed that if you gave whales and dolphins a few more million years of evolution, the pelvic bones would disappear. But it appears that’s not the case,” said Matthew Dean, assistant professor at the USC Dornsife College of Letters, Arts and Sciences, and co-corresponding author of a paper on the research that was published online by Evolution on Sept. 3.
Dean collaborated with fellow co-corresponding author Jim Dines, Collections Manager of Mammalogy at NHM and one-time a graduate student in Dean’s lab, on a painstaking four-year project to analyze cetacean (whale and dolphin) pelvic bones.
The muscles that control a cetacean’s penis — which has a high degree of mobility — attach directly to its pelvic bones. As such, it made sense to Dean and Dines that the pelvic bones could affect the level of control over the penis that an individual cetacean has, perhaps offering an evolutionary advantage.
“Our research really changes the way we think about the evolution of whale pelvic bones in particular, but more generally about structures we call ‘vestigial.’ As a parallel, we are now learning that our appendix is actually quite important in several immune processes, not a functionally useless structure,” Dean said.
Anyone who has been discussing evolution for any length of time is familiar with the scientific terms “perhaps”. Actually, I’ve never had a discussion with an defender of evolution (who I could actually get to offer an explanation) where the supposed explanation wasn’t thick with speculative language. It’s all maybes, perhapses, resembleses, and possiblys.
Every once in a while a scientific discovery unfolds and upends the common thought of the day. This time it seems that what has always been regarded as a vestigial remnant of land habitation actually turns out to be a fully and properly functioning feature of the animal’s reproductive system. Imagine that.