Your Inner Fish Book Summary - Your Inner Fish Book explained in key points

Your Inner Fish summary

Name: Your Inner Fish
Rating: 4.7 (16 reviews)
Author: Neil Shubin

Neil Shubin

A Journey into the 3.5-Billion-Year History of the Human Body

4.7 (16 ratings)

19 mins

Topics

The Body Natural Sciences Animals Life Sciences Change & Evolution

Table of Contents

Your Inner Fish
Summary of 11 key ideas

Audio & text in the Blinkist app

Key idea 1 of 11

What’s in it for me? Find out how fish can tell us a whole lot about ourselves.

Researchers are endlessly at work exploring the history of our planet and its many species, both living and extinct, to gain new insights into our past.

In 2004, the author and his team discovered the Tiktaalik fossil, representing the bridge between life in water and life on land: a milestone on our path towards understanding the evolutionary development of humans. If animals had never emerged from the water, we humans wouldn’t exist.

But it was a long evolutionary journey before today’s human was fully developed, and now we’re trying our best to understand this gradual transformation.

In these blinks, you’ll find out:

what humans have in common with fish,
how hiccups are due to our fishy past,
the price we pay for our ability to talk and
why a fish doing push-ups might not be as strange as it sounds.

Layer by layer: fossils teach us about the landscape, climate and species of former times.

Fossil fuels are very important for meeting the high energy demand in our modern society. But fossils have another significance: they help us understand our planet’s past and the creatures that lived a long time ago.

After all, sea shells have been found on Mount Everest – evidence that an ocean once existed there – and fossils from warm-adapted animals have been found in the icy Arctic, proof that the region once had a tropical climate. Moreover, many well-preserved fossils have been found in hot, arid, sparsely populated deserts like the Sahara, indicating that they were once full of water and life.

And so, layers of rocks and the fossils they contain can expose the evolutionary development of different species and animal groups because the order of the layers always reflects their age.

Let’s take the tetrapods, an animal group comprising amphibians, reptiles, birds and mammals, all of which are characterized by having four limbs, a backbone and lungs.

Scientists found fossils of the first land-living tetrapods in rocks dating back no more than 365 million years, meaning that this group of animals appeared 365 million years ago. But they had no evidence of how the tetrapods developed, since there was a gap in the fossil record: fish fossils had been found in rocks that were older than 380 million years, but nothing else had been found in between these two animal groups.

That is, not until the author’s workgroup discovered the Tiktaalik fossil in a 375-million-year-old rock. Tiktaalik had body features similar to a fish, such as scales, fins and webbing, but also a flat head with two eyes on top and a neck – the characteristics of a land-living tetrapod. In other words, it had traits from both groups of animals, thus representing a link between life in water and life on land.

It’s in our bones: similar bone designs can reveal how different species are related.

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.

Bones and teeth show us how variations of the same body parts fit different types of lifestyles.

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.

Some of our genes can also be found in other species, revealing an evolutionary relationship.

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?

Bodies started to develop when multicellular organisms had enough oxygen.

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.

A body has a special plan to put everything in its right place.

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.

The embryonic development of our head shows us our inner fish.

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.

Our ears evolved from bones and organs that have nothing to do with hearing.

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 shows our relationship to other animals.

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.

Our visual system became more important and has changed for the better.

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.

Some problems and everyday inconveniences are related to our evolutionary background.

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.

Want to see all full key ideas from Your Inner Fish?

Key ideas in Your Inner Fish

More knowledge in less time

Read or listen

Get the key ideas from nonfiction bestsellers in minutes, not hours.

Find your next read

Get book lists curated by experts and personalized recommendations.

Shortcasts ^New

We’ve teamed up with podcast creators to bring you key insights from podcasts.

What is Your Inner Fish about?

Drawing on findings from paleontology, genetics and developmental biology, Your Inner Fish describes the evolutionary history of the human body, tracing it back to the fish. The author shows how studying fossils, genes and embryonic development can help us understand our complex evolutionary past.

Best quote from Your Inner Fish

Tiktaalik is a wonderful intermediate between fish and their land-living descendants, but the odds of it being our exact ancestor are very remote. It is more like a cousin of our ancestor.

—Neil Shubin

Who should read Your Inner Fish?

● Anyone who wants to know more about our evolutionary past
● Anyone interested in genetics, developmental biology and paleontology
● Anyone who wants to know how we can detect the inner fish in our bodies

About the Author

Neil Shubin is a paleontologist who teaches anatomy and biology at the University of Chicago. He and his work group discovered Tiktaalik, a fossil that helped clarify an evolutionary step from fish to human. Shubin also wrote The Universe Within: Discovering the Common History of Rocks, Planets and People.

Categories with Your Inner Fish

History Science

Books like Your Inner Fish

Podcasting Marketing Strategy

Daniel Rowles and Ciaran Rogers

A Complete Guide to Creating, Publishing, and Monetizing a Successful Podcast

21 min

4.2

Understanding and Responding to Self-Harm

Allan House

The One-Stop Guide: Practical Advice for Anybody Affected by Self-Harm

A Journey Through the Money, Medicine, and Mysteries of Blood

24 min

4.4

Talk to Me Like I'm Someone You Love

Nancy Dreyfus

Relationship Repair in a Flash

9 min

3.9

Habits of a Happy Brain

Loretta Graziano Breuning

Retrain Your Brain to Boost Your Serotonin, Dopamine, Oxytocin & Endorphin Levels

Proven Strategies for Getting Up to Speed Faster and Smarter

Four Simple Choices to Scale Your Impact

How Google, Bono, and the Gates Foundation Rock the World with OKRs

20 min

4.5

The Algebra of Happiness

Scott Galloway

Notes on the Pursuit of Success, Love, and Meaning

An Ancient Guide to Wise Leadership

How to Create Extraordinary Teams that Get Tangible Results

20 min

3.8

The Laws of Human Nature

Robert Greene

What affects your day-to-day life

How the Tech Titans and Their Thinking Machines Could Warp Humanity

The Philanderer, Gambler, and Duelist Who Invented Modern Finance

The Reality of Racism and Oppression of Women in 1940’s America

On the Possibilities and Limits of Forgiveness

Philby and the Great Betrayal

Transforming Self-Sabotage Into Self-Mastery

A Spiritual Guide to Epic Leadership

21 min

4.3

The Happiness Project

Gretchen Rubin

Or, Why I Spent a Year Trying to Sing in the Morning, Clean My Closets, Fight Right, Read Aristotle, and Generally Have More Fun

Our Enduring Fascination with the Most Mysterious Creature in the Natural World

22 min

4.5

(Article) Why can't the world's greatest minds solve the mystery of consciousness?

Oliver Burkeman

Original article published in The Guardian

The Politics of Feeling Good

How to Get What You Want by Living Fearlessly

A One-Year Guide to Reading and Understanding the Entire Bible

How Leading Organizations Are Upending Business as Usual

Transforming Your Life One Night At A Time

A New Approach for Understanding and Parenting Easily Frustrated, Chronically Inflexible Children

How a Remarkable Chinese Company Is Changing the Face of Global Business

15 min

3.8

Subscribed

Tien Tzuo with Gabe Weisert

Why the Subscription Model Will Be Your Company’s Future – and What to Do About It

30 min

4.2

What Truth Sounds Like

Michael Eric Dyson

Robert F. Kennedy, James Baldwin, and Our Unfinished Conversation About Race in America

What the Brain Does When You’re Not Looking

12 min

4.2

Impromptu

Reid Hoffman with GPT-4

Amplifying Our Humanity Through AI

17 min

4.3

Influence is Your Superpower

Zoe Chance

The Science of Winning Hearts, Sparking Change, and Making Good Things Happen

Reflections on Life, 50 Years in Venture Capital, and Never Driving Alone

29 min

4.1

Why Don’t Students Like School?

Daniel T. Willingham

A Cognitive Scientist Answers Questions About How the Mind Works and What It Means for the Classroom

7 Biblical Principles for Being Purposeful, Present, & Wildly Productive

16 min

4.0

The Surprising Science of Meetings

Steven G. Rogelberg

How You Can Lead Your Team to Peak Performance

21 min

4.3

The New Confessions of an Economic Hit Man

John Perkins

An insider's account of imperialism in the modern age

26 min

4.4

The Hidden Wealth of Nations

Gabriel Zucman

The Scourge of Tax Havens

The Science of Seeing Differently

The Israelis and the Holocaust

The Surprising Truth About What Motivates Us

A Journey Through Middle Earth—A Lord of the Rings Prequel

21 min

4.5

Leadership and the Rise of Great Powers

Yan Xuetong

How leadership determines the fate of nations

25 min

3.8

Invisible Women

Caroline Criado Perez

Exposing Data Bias in a World Designed for Men

27 min

4.6

The Power of Pressure

Dane Jensen

Why Pressure Isn’t the Problem, It’s the Solution

The Mavericks Who Brought AI to Google, Facebook, and the World

A Guide to Our Future

16 min

3.9

The Goal

Eliyahu M. Goldratt and Jeff Cox

A Process of Ongoing Improvement

16 min

3.6

People ❤️ Blinkist

Sven O.

It's highly addictive to get core insights on personally relevant topics without repetition or triviality. Added to that the apps ability to suggest kindred interests opens up a foundation of knowledge.

Thi Viet Quynh N.

Great app. Good selection of book summaries you can read or listen to while commuting. Instead of scrolling through your social media news feed, this is a much better way to spend your spare time in my opinion.

Jonathan A.

Life changing. The concept of being able to grasp a book's main point in such a short time truly opens multiple opportunities to grow every area of your life at a faster rate.

Renee D.

Great app. Addicting. Perfect for wait times, morning coffee, evening before bed. Extremely well written, thorough, easy to use.