Whales journey from land to sea
Scientists have long believed that whales came from land animals, but until recently that evolutionary journey from four-legs to flippers was a mystery. That is until paleontologist Hans Thewissen entered the field. He says his predecessors were just looking in the wrong place, since most of these fossils are in India and Pakistan.
Thewissen teaches anatomy at the Northeast Ohio Medical University in Rootstown. But his passion is whale research. His discovery in the early 1990’s of the Walking Whale, Ambulocetus, and other fossil whales, filled the gaps so well that story of whales is now one of the best understood in evolutionary biology.
He no longer travels to Pakistan in search of fossils, instead Thewissen heads to the northernmost tip of America to study bowhead whales caught by the Inupiat of Barrow, Alaska. That’s where he made another discovery.
“We took a brain out, and this is very difficult, bowhead’s have a very thick skull so we used a chainsaw to cut through the skull roof, took the brain out - and then I noticed this bony tunnel from the brain to the blowhole – the nasal passages the nose.”
Thewissen found bundles of olfactory nerves running through the tunnel, and when he weighed the whale’s brain …
“Sure enough the parts of the brain that are related to olfaction are actually much bigger than olfaction parts in a human.”
Baleen whales hunt by smell
That, among other tests clinched it - whales can smell. Scientist had always assumed that since they live in water, a sense of smell was lost along with their legs. Thewissen is the first to disprove that. But he says it wasn’t news to the Inupiat - “They said ‘now tell me something I didn’t know already”. But for the science community this was quite a shock.
The Inupiat know that when a whale smells the odor of krill near the water’s surface, they make a bee-line for it. And since the Native Alaskans rely on the bowhead for sustenance, they worry about the odors of oil exploration. They say drilling disturbs the whales’ breeding and migration, and the odors of oil and gas in the air prevent the whales from finding food.
That’s why the Inupiat welcome Thewissen’s research because it helps environmental officials make informed decisions about how oil exploration does and does not affect the populations of whales.
Whale necks and human hips
Meghan Moran is a graduate student working with Thewissen at the medical school. She traveled with him to Alaska to study another part of the whale – the bowhead necks.
In the lab she holds a bloody slice of bone the size of a serving tray. Moran counts bumps in the neck taken from a 50 foot bowhead whale… "one, two, three, four, five, six, and seven...”
All mammals, even giraffes, have seven neck bones. But in whales these bones fuse together into a solid piece. The bowhead whale needs a stiff neck to keep its huge head steady while swimming. The necks of land animals, like humans, are loose but the sacral bones that hold our hips are fused together.
Thewissen dips into his collection of fossil whales to show that whales once had hips like humans. He holds the pelvis of Ambulocetus, and counts the fused vertebrae…”one, two, three, four fused vertebra just like the early whales.” He says this was very much a land animal, living in the water but still was using its hind limbs.
But over time, as whales evolved into ocean going creatures, the bones in their sacrum separated, while the bones in the neck fused together.
Vertebral fusion - whales, mice, & people
Moran and Thewissen reviewed previous research and found none knows the process of how vertebrae fuse or stay separate. Moran is uncovering the molecular pathways, but acknowledges, “we don’t know if it’s the same mechanism between sacral fusion and neck fusion in whales. That’s what we’re trying to find out.”
By studying mice vertebrae in the lab, Moran is probing the changes in the inter-vertebral disk, how that changes from cartilage to bone, and what makes those changes happen.
What they find could help humans with neck or lower back trouble. Thewissen says doctors at the Rootstown medical school are hoping his research might someday lead to a replacement of the metal hardware used to fuse vertebrae in spinal patients.
But Thewissen says a change that took millions of years in whales may take decades to perfect in people needing surgery.
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