The Curious Case of Whale Evolution

Note: this is not the evolution we as Steemians dream of (redfish->minnow->dolphin>whale). This post is about the theoretical evolution chain of an actual whale :)

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If you read our previous chapter of the Potato Thoughts series. We have said that Charles Darwin's "Theory of Evolution" might be one of the most substantial theories of science. But like any other theories, Darwin's is not of absolute certainty. Actually, it is not only popular because of the evidences that supports it but also due to the number of critics and their controversial citations of 'flaws' against this theory.

According to one of Darwin's critics, Soren Lovtrup, only a minority of his(Darwin's) critics came from the religious faction while the most of them came from the scientific community. Lovtrup was known for his macromutation theory of evolution, Darwin on the otherhand was a pursuer of the gradualistic theory of micromutation. In Lovtrup's book, Darwinism: Refutation of a Myth, he disclosed the following statement,

"...the reasons for rejecting Darwin's proposal were many, but first of all that many innovations cannot possibly come into existence through accumulation of many small steps, and even if they can, natural selection cannot accomplish it, because incipient and intermediate stages are not advantageous."

Lovtrup like most critics believed that there were too many puzzle pieces (missing links) to justify the concept of micromutation.

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Actually, after Darwin sold the first 1250 copies of his book he faced no small amount ridicule from the public. Darwin hypothesized about how a land mammal would turn into today's largest known sea creature, a whale. Having observed how an American black bear found food while swimming, he came up with the following statement,

"I can see no difficulty in a race of bears being rendered, by natural selection, more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale,"

In Darwin's embarrassment this statement was removed from the later editions of his book. But modern scientists believed that Darwin's hypotheses holds significance, the only problem was that he got the wrong animal. According to them, cows and hippos have highest probabilities of relationship with whales.

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The Evolution of Whales

livescience.com
The Evolution of whales is one of the most baffling yet fascinating tales of natural selection.

Scientists have traced their origin to an amphibious mammalian tetrapod which walked on earth 360 million years ago. Let us see below some of the early 'ancestors' of whales.

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Sinonyx(~60 million years ago)

Sinonyx(Chinese claw) was a prehistoric mammalian tetrapod about 5 feet long. It has short limbs with tiny hooves on its toes. Due to having a very large elongated head and short legs it was built for power more than speed, the sinonyx was speculated to be a slow killer and believed to be a scavenger near the coastlines.

Similarities with whales:
• Tooth shape and snout have close similarities with ceteans(whales and dolphins)

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Indohynus(~45 million years ago)

Indohynus(India's pig) was an omnivorous pig-like creature that was about the size of a domestic cat. Their remains exhibited bone structures which are very similar to the modern day hippos.

Similarities with whales:
• Presence of ectotympanic bone in its ear which is present only to living and extinct ceteans.
• showed signs of adaptation to aquatic life(could dive up to 4 minutes)

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Ambulocetus(~43 million years ago)

Ambulocetus(walking whale) is believed to had the same size of a male sealion. They had relatively short limbs with 5 fingers each. Their noses was able to swallow water which made them fully aquatic. Ambulocetus killed its prey by holding and thrashing, like those of the crocodiles.

Similarities with whales:
• fully aquatic
• periotic bone structure that let it hear underwater
• swam the waters by undulating its back
• eyes located sideways of the face

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Rodhocetus(~44 million years ago)

Rodhocetus(anticline whale) was one of the earliest whale "ancestors" that exhibited transition from land to sea. It had short hind legs and large frontal legs, which are theorized to be webbed.

Similarities with whales:
• adapted to aquatic life(predominantly aquatic)
• used its tail as a rudder(characteristic of few ceteans)

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Basilosaurus(~35 million years ago)

If you watched the movie Jurassic world, basilosaurus(king lizard) might not be new to you. It was the large aquatic dinosaur in the pool-like coliseum.

Basilosaurus was humongous its remains measured up from 49ft. to 59ft. The basilosaurus is believed to be unsociable and less intellectual than modern whales.

Similarities with whales:
• although underdeveloped it had an auditory system similar to whales
• it had asymmetrical head structure which is very close to the modern toothed whales

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Dorudon(~34.5 million years ago)

Dorudons(spear tooth) are speculated to live alongside with the basilosaurus. They were more or less 16ft in length and mostly preyed from mollusks. Dorudon remains indicated that they lived in warmer seas.

Similarities with whales:
• fully aquatic
• like the basilosaurus, Dorudon had an auditory system which greatly resemble those of the modern whales but both Dorudon and basilosaurus failed to have the ''melon organ", which should have allowed them to use echolocation
• relies mainly on tail for movement

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After the Dorudons the earliest whales appeared,
Squaldon(~25 mya)(order Odontoceti, toothed whales)
Kentriodon(~20 mya)(order Odontoceti, toothed whales, first dolphins)
Aulophyseter(~20mya)(order Odontoceti, toothed whales, first sperm whales )
Brygmophyseter(~15mya)(order Odontoceti, toothed whales, sperm whales)
Aetiocetus(~27mya)(order Mysteceti, baleen whales)
Janjucetus(~25mya)(order Mysteceti, baleen whales)
Cetotherium(~18mya)(order Mysteceti, baleen whales)

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Fast forward to the present
And now this chain of evolution led to present Whales(and dolphins)

The present ceteans are armed with a very powerful asset their predecessors didn't manage to have, the melon organ, which is the organ they use for echolocation. And unlike the ancients they have evolved their intellect and social skills, giving them greater chances for survival.

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Final thought from a potato

The evolution of whale is indeed fascinating. From a monstrous creature of the wide oceans and seas we managed to trace it back to its humble beginnings, an amphibious mammalian tetrapod. It took hundreds of millions of years for a small mammalian lifeform to evolve into something extraordinary. And to come up with ideas like these, scientists like Charles Darwin are badly needed. He stirred the minds of critics, producing more intellectual individuals. Friend or foe we couldn't deny his contributions to humanity. Right or wrong, we could say that it would be a great help to anyone who study this field, called evolution.( So many thanks Charles :))

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Are you fascinated by the evolution of whales? Do you think man in a million years would evolve into something extraordinary?

Please share your thoughts below.

Thank you very much for reading.

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Credits:
nationalgeographic.com
livescience.com
wikipedia.org/Soren_Lovtrup
arn.org
wikipedia.org/sinonyx
wikipedia.org/indohynus
wikipedia.org/ambulocetus
wikipedia.org/rodhocetus
wikipedia. org/basilosaurus
wikipedia.org/Dorudon
wikipedia.org/evolution_whales
ALL IMAGES AND GIFS (not credited) ARE FROM PUBLIC DOMAIN

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