Name: How Did Whales Evolve From Land Mammals?
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The oceans are thought to be where life started but about 50-million years ago, something incredible happened: some mammals found their way back into the water.

The story of whales’ evolution from land mammals is hidden in their genes.

How Did Whales Evolve From Land Mammals?

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The oceans are thought to be where life started but about 50-million years ago, something incredible happened: some mammals found their way back into the water.

The story of whales’ evolution from land mammals is hidden in their genes.

How Did Whales Evolve From Land Mammals?Published: August 5, 2024Speaker 1: All whales and dolphins have this unexpected feature of multiple stomach chambers. It's a trait they inherited from their ancient relatives that walked on land.Speaker 2: Just like cows have multiple stomachs to digest their plant matter, whales have multiple stomachs to digest what they're eating, which is completely different, fishes and squid, but it's still coming from the same structure as a terrestrial mammal.Speaker 1: This anatomy is more evidence that whales are related to hoofed mammals. And this terrestrial heritage can even be revealed in their genes. In his lab, Michael uses modern whales' DNA to map their past. It's opening up a vast new world of information about the origins of whales.Speaker 2: So if you think about different marine mammals such as a manatee or a seal, sea lion, they all swim and live in the ocean and have similar adaptations to whales and dolphins. But we can look at the DNA to see whether whales and dolphins are closely related to those other groups or whether they're related to another species entirely.Speaker 1: Scientists wanted to identify the whales closest living relative, so they compared whale DNA with a range of other animals.Speaker 2: They came up with a really surprising finding, and the finding was that the whales closest relative using DNA was the hippo.Speaker 1: Whales and hippos both descended from a common hoofed ancestor that lived about 5 million years before Pakicetus.Speaker 2: Some of the earliest whales like Pakicetus may have lived like hippos. Also, hippos give birth underwater. They nurse underwater. Their skin is also very thick. So it's interesting to think that maybe the common ancestor of whales and dolphins had these particular features.Speaker 1: But life in the ocean is very different from life on the riverbank. Over time, whales ancestors adapted to this new environment. Scientists compared the DNA of hippos and whales to find out how.Speaker 2: Genome of whales. We see that whales still have a lot of the genes from when they used to live on land. So they still have genes involved in smelling, sweat glands, color and vision, producing saliva. But these genes are inactivated and they gradually degrade. But I think this is incredibly powerful evidence that shows that whales come from land ancestors, that they still have these genes in their genomes, even though they're inactivated.

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How Did Whales Evolve From Land Mammals?

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The whale that could walk

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