Your Inner Fish summary

Can you imagine a fish doing push-ups, with its gills flapping and fins flopping? A pretty absurd image, it’s true, but the disposal of bones shows that Tiktaalik was actually able to do push-ups. The creature could place its fins flat on the ground, bend its elbows and use its chest muscles just like humans.

Some of our joints can be traced all the way back to animals like Tiktaalik, part-fish, part-tetrapod. Even though Tiktaalik looked like a fish with the head of a crocodile and lived in the water, it shared some body features with the human species.

Different species face different challenges and have thus needed to adapt to their environments. Scientists can track these adaptations with the help of bones and teeth.

Different kinds of limbs help tetrapods manage their lifestyles. To ensure their survival, tetrapods colonized different parts of the world and developed different abilities – e.g., birds gained the ability to fly and whales returned to the oceans.

We know that the more similar the DNA of different species, the stronger their relationship. And tetrapods all have a shared gene that initiates the development of limbs.

In one experiment, scientists took a chicken embryo early in its development and transplanted a small bit of tissue from the pinky side of what would become a limb bud to the thumb side. The result was surprising: the chicken developed an extra, mirrored set of fingers on the thumb side. How could this have happened?

Our earth is full of creatures with extremely diverse appearances today. But life on earth looked quite different a billion years ago: our planet was home to exclusively unicellular organisms like bacteria. So why and how did such different-looking bodies develop?

Simply put, because there are benefits to having a body. In a world full of unicellular organisms, multicellular organisms and bodies can easily find prey and avoid becoming prey: that’s a big selective advantage. Bodies can also move faster and travel for longer distances.

At the beginning of embryonic development, animals are nothing but a mere cluster of cells, and the cells need to organize themselves so that all the organs develop in the right position.

In fact, all vertebrate organs grow from three layers of tissue called germ layers during embryonic development.

Our head is a very complex and powerful body part, which makes it hard to believe it was once nothing but a glob. But out of that glob, the arches develop: four structures that look like swellings and initiate the development of the head.

Here’s what each of them do: the first arch is responsible for the development of the two ear bones and the jaws; the second forms the third ear bone and muscles needed for facial expressions; the third and fourth are in charge of the development of the throat, which allows us to swallow and talk. Each of the arches also forms the appropriate nerves and muscles.

Mammals have many defining body features in common, such as milk-producing glands, but there are also less obvious parallels, such as the three middle ear bones.

Actually, those three middle ear bones evolved from jaws.

Our sense of smell is incredibly important to us. For example, it helps us differentiate between edible and poisonous food. And this rather sophisticated sense of smell can actually be traced all the way back to fish.

Fish also have a sense of smell, though there are some differences in the structures of our organs.

Sight is arguably the most important of the senses for humans – so much so that around 70 percent of all human sensory cells are light-sensing cells. But, looking back at our primal ancestors, we can see that it hasn’t always been that way.

Fossil records show that the flora of our planet changed approximately 55 million years ago. Before that occurred, the forests consisted mainly of green plants, like fig and palm trees. However, when the changes took place, the biodiversity of plants started to increase and forests became more colorful.

Our human lifestyle is very different to that of our animal ancestors. Rather than spending all day outside hunting, the majority of us spend most of our time sitting at our desks in front of computers.

And since our bodies were built to be more active than most of us are, many people suffer from heart diseases and obesity. But there are other adaptations to our lifestyle that have caused problems for us.