u/Hegde137

I always wondered how we have all collectively agreed that this is the year 2026. How did these calendars come to be? There were no clocks 1000 years ago. Timekeeping was done by elites in society, and even minor inaccuracies could have hugely disrupted the timeline when it is done over centuries. We have no real way of knowing how well they did their job.

Or at least, that’s what I thought until I read this book!

I am not sure if this should be called a "brief history", because for a common reader like me, this is a near-comprehensive overview of how humans have kept time throughout history. Beginning with the Egyptian calendar and Stonehenge, and moving all the way to the evolution of atomic clocks, the book discusses various ideas and concepts humans developed to track time. If you are interested in astronomy, this book is a goldmine. It taught me many things about the positions of the sun and moon throughout the year, the drifting of equinoxes over long periods of time—which eventually led to the origin of the Gregorian calendar—how the positions of stars and planets shift over time, and more.

One thing to note is that the author doesn't hesitate to dive deeply into technical explanations. So it does get quite heavy at times, but the figures certainly help with visualization. An ingenious feature of the book is that the pages containing technical explanations have dark-colored edges, allowing you to skip them if you are only interested in the historical aspects of timekeeping.

With this book, I now have a new outlook on stargazing. I have started noticing the positions of sunrise and sunset, the phases of the moon, and the position of our beloved Venus. I also understood why Venus appears either as a morning star or an evening star—a simple concept that I probably could have figured out earlier, but it never crossed my mind (too embarrassed to confess this!).

Nevertheless, I enjoyed reading this book. In fact, it had one of the best explanations for the origins of quantum physics, which I wasn’t expecting. That was a pleasant surprise. I would give this book a 4/5, mainly because a few chapters were quite dense and required some googling and ChatGPT to fully understand. But that’s only about 5% of the book. I certainly didn't mind that.

There is a line in the book: “Ontogeny recapitulates phylogeny”.

When we think about evolution, our minds quickly associate it with the fossils—the ancient remains which tells the stories of organisms that lived on this planet millions of years ago. We rarely think about something that exists in abundance around us, albeit not in plain sight: the embryos. The stages of embryonic development tell us the story of our own origins just as much as fossils do, if not more!

Neil Shubin takes us on this journey of understanding our origins by examining how embryo develops into an individual organism. It is fascinating as well as humbling to realize how similar we are to fish, birds and other mammals. The “technology” through which our hands emerge from a blob of cells in an embryo is the same technology that brings out feathers in birds, and fins in sharks. The genes responsible for this process exists across species. It is freaking unbelievable and, at the same time, unsurprising to learn that if genes responsible for limb development in a chicken are transferred to a fly, the fly can develop an extra wing.

As much as we humans consider “birth” a miracle, modern-day technological prowess—which has enabled us to inspect embryonic development at the molecular level—shows us that genes hold many secrets to life’s origins. Richard Dawkins famously described all living organisms as “gene machines”, and this book further solidified that notion for me. It shows how our genes have repurposed and reused certain organ-making processes to develop different organs across species. Anything that grows out of skin—hair, nails, teeth, mammary glands, feathers—is engineered using variations of the same underlying design. We are, in many ways, machines indeed.

One might think this all sounds fairly intuitive. Does one have to read an entire book to understand this? Yes, you do. Understanding the similarities in organ development across species has broader implications for how complex organisms came to be.

Think about this: Earth is over 4 billion years old. Yet until around 380 million years ago, life was largely confined to the oceans. There were no land-dwelling reptiles or mammals, and many of the large fish we see today had not yet evolved. But within the following 30-40 millions of years, the planet became populated with vertebrates. Is that not remarkable?

It is—but no more remarkable than the fact that genes responsible for wing development in birds can, in controlled environments, develop wings for flies. Everything begins to make sense when you understand how and why single-celled organisms evolved into complex, multicellular life. And to truly appreciate that, you must read this book.