For a long time, people believed that the hippopotamus was most closely related to the pig. This was because both animals have large bodies and similar foot structures. However, modern science has discovered a much more surprising family connection.
It turns out that the closest living relatives of whales and dolphins are actually hippos. These two groups of animals belong to a special suborder called Whippomorpha. This name was created to describe the unique link between these very different-looking creatures.
While whales live in the deep ocean and hippos live in rivers, they share a history that goes back millions of years. They are more like cousins than any other living species on Earth.
The Genetic Connection
Scientists used DNA testing to find the truth about how these animals are related. According to PennState Eberly College of Science, genetic analysis shows that hippos and whales share many segments of DNA that other mammals do not have. This proof is much more reliable than just looking at how an animal is shaped.
One study looked at specific genetic markers called short interspersed elements (SINEs) and long interspersed elements (LINEs) that move around in the DNA. These markers are found in the same spots in both whales and hippos. This suggests that they both inherited these markers from the same ancestor.
Moreover, these two groups also share nearly 11,000 similar genes. These genes help provide a clear map of their shared evolutionary history. This evidence is so strong that most scientists now agree that the pig is not the hippo's closest relative.
Even though they look very different, whales and hippos actually share many physical traits. Both animals have bodies that are mostly hairless and have a thick layer of fat under their skin. This fat helps them stay warm and store energy while they are in the water.
Their internal organs are also very similar, such as their multi-chambered stomachs. Both animals have lungs that are shaped in a way that lets them take in air very quickly. This is an important tool for mammals that spend a lot of time underwater.
Another shared trait is the way they talk to each other under the water. They both have large voice boxes that allow them to make loud, booming calls. These sounds can travel through the water to help them communicate with their groups.
A Shared Evolutionary History
Whales and hippos share a common ancestor that lived about 55 million years ago. This ancestor was a small, deer-like creature that walked on four legs. Over millions of years, this one family split into two different directions.
One branch of the family moved completely into the sea and became the whales we see today. The other branch stayed near the water and eventually became the modern hippopotamus. Fossil discoveries, like the Indohyus, have helped scientists fill the gaps in this long story.
These two groups actually adapted to life in the water at different times. However, their aquatic features, like smooth skin, might have evolved separately. This means that while they are related, they found their own ways to survive in wet environments.
