Whale of a time

Ever seen a whale jogging in the park? Were you around 47 million years ago, you?d have come across one on your early morning run.

Ever seen a whale jogging in the park? Were you around 47 million years ago, you’d have come across one on your early morning run. And perhaps wondered why, far into the future, in 2005, the journal Science should face flak from proponents of intelligent design (ID) for choosing research on evolution as the top science achievement of the year. ID theorists challenge Darwinism saying some systems in the world are too complex to have been the result of natural selection. Their belief that an intelligent supernatural force drives evolution flies in the face of fossil evidence. Such as that unearthed in Pakistan in 2001, which bore features of whales and land mammals, proving that whales, dolphins and porpoises — or cetaceans — evolved from four-legged land mammals. These wolf-sized animals ran about on land 50 million years ago and could be the ‘missing link’ between primitive hoofed mammals and the whale family. In other words, the mighty whale had its origins within the ungulate (hoofed animal) group and probably used webbed hind legs to swim in water like otters, as well as to move on land.

HT Image

This whale of a tale is part of the fascinating evolutionary history that DNA imprints on fossils, millions of years old, have revealed since the Eighties. Geneticists open family albums of various species by comparing DNA of different animals. Every animal inherits chunks of DNA specific to its species that appear at precisely the same place in its genetic code, or genome, as they did in its ancestors. This helps genetic sleuths sketch evolutionary trees like the one showing how whales are more closely related to cows, camels and pigs than to horses, elephants or sea cows. In fact, the whale’s closest relative is the hippopotamus.

Of course, you wouldn’t recognise the ancient Moby Dick for the simple reason that it has undergone dramatic changes since first wading into the sea. Gone are its hind limbs; and the front limbs have become flippers. The only physical similarities with ungulates are aquatic adaptations like the absence of hair and sebaceous glands. Vocal communication of ungulates (like grunts, moos, and barks) corresponds to the amazing whale songs (emitted underwater at frequencies close to the lowest octave on a piano keyboard).

Just as specialised organs and abilities like the brain and upright walking habit helped man dominate land, a scaled-down inner ear (the semicircular canal system) helped cetaceans adapt to their marine environment. The inner ear gives land mammals, including humans, a sense of balance (most of us realise this when drunk, airsick or on a roller-coaster.) A whale’s inner ear, however, is much smaller and less sensitive, helping the mammal make spectacular leaps and turns unaffected by vertigo: Darwin’s grand theory of evolution in action. Never mind if ID enthusiasts are unimpressed.