Thomas Perry, an artist and designer living in Osaka, sends this timeline companion to our current cover story on the 50 most significant breakthroughs since the discovery of the wheel. He explains his approach:

I spent a couple of hours creating a timeline in a class I teach on basic design to interior, product and graphic design students in Japan. I agree with a point you made on your blog that the changes at that time had a much more jarring impact on day-to-day life compared to the present, although dispersed into general society at a slower pace compared to recent inventions.

A few explanatory points:

* I start the 20th century at the sinking of the Titanic - all of the promise of recent technology with the dark hint of what`s to follow. A case could be made that electrification starts the 20th century but my guess is that it did not truly penetrate (western) society until after 1912, more likely not until the `20s. I close the 20th century at the airing of the Apple "1984" Mac commercial and the beginning of the digital age on a commercial level. An explanation of Orwell`s book is also necessary.

* on occasion I use 2 dates to mark an invention, for example, photography:  1827 for the introduction of the first daguerreotype and then the early *1900`s as the vague starting time for general use. When I ask the students to fill in the timeline from the list of inventions that we draw up, I emphasize that they should pick dates when the item truly becomes relevant to general society, otherwise electricity and automobiles first make their mark in the 1600`s.

*interesting how certain events can be dated to the day, airplanes and WW 1, but most have a vague time span, automobiles, the starting point of WW 2 in Asia, the cell phone, email, etc.

* I noticed in your article you put refrigeration as starting in the 1850`s, I place it at 1927 and the introduction of the electric refrigerator for home use .... the freezer does not make it into the home until the 40`s according to my brief research on the internet...

Now, other reactions from readers. First, what about the threshing machine

While I could quibble with some of the rankings, etc., the biggest flaw is the combine harvester [#50 on our list].  While important, this was merely an improvement over the real leap forward, the invention of McCormick threshing machine.  Before that, grain had to cut by hand with a sickle (which was itself probably a pretty important invention).  More so than the moldboard plow, this is what really made large scale farming feasible and started the movement of people off the farms into the cities.   

What about the semaphore?

The quote about the telegraph ("Before it, Joel Mokyr says, “information could move no faster than a man on horseback.”) is incorrect.  As early as 1795, messages from London to Deal (about 75 miles) were regularly being sent in about one minute.  Other European cities probably were doing it even earlier.

The Semaphore Line, invented and developed by various Europeans in the late 18th century, was so quickly and throughly eclipsed by the electric telegraph that it is largely forgotten today.  But for several decades it could send messages quite quickly across great distances,  assuming the cooperation of weather and finicky machinery.

What about the horse collar? From a reader in Zurich:

Clearly there would have been great diversity in the lists presented by each panelist, but I would be curious to know if anyone had mentioned the horse collar (possibly as early as the 3rd century AD.)  [JF note: I don't recall anyone suggesting this, but I'll check again.]

Years ago in an undergraduate history course, we were made aware that this invention enabled man to use a more powerful animal to plow, expand production from subsistence level, and, ultimately, enable the formation of cities.  It still sounds pretty important to me.

What about baskets?

But before I read down to the details of the piece I stopped myself and wrote my own choices for the list.  Such lists, though, are troubling because they strive to be unconditional:  the Gutenberg press is fine alone, except what about cheap paper?  Ooops, and the alphabet? So, like your correspondents, I varied the list into clusters of like objects, each of which made something else possible.  That became my criterion:  the power of what is made possible by the invention or innovation.  The great mind may be a combinatory mind.

So:  wheel is fine.  Wheel + axle is better because it seems to show more possibility in its genius. Hammer-stone, cutting-stone, stone scraper, stone spear, atlatl, are all the same, because they permitted human beings to plan for things like hunting, prepare things like food and clothes, and make shelters.  Higher intellect begins for me in planning, preparing and making -- and then replicating these activities in an adaptive way.  We could add controlled fire + cookery to the list, probably, and the adaptation of materials for tools, weapons, shelters, and food as well.  (Also, some kind of primitive balanced meal must have allowed robust survivors to emerge with expanded brains.)

Maybe a shorter list of processes is needed as well:  not just invention but also adaptation, combination, cultivation, imitation, experimentation, evaluation, differentiation, judgement.  Welcome, people, to complexity and ambiguity.

An insight I had at the American Museum of Natural History in 1983 or 1984 made me add baskets to my list ("a world with a basket is better than a world without a basket," that was my thought when contemplating the native people of the American Plains).  But that thought has to be broadened to include all kinds of containers and vessels made of glass, pottery, metal.  Imagine a world without portable storage, cooking containers, drinking gourds.

What about justice for Eli Whitney? A reader whose last name is Whitney writes:

For my own selfish reasons, I was pleased to see that Eli Whitney made the list by virtue of the cotton gin.  However, I feel he was slighted by not being given credit for the introduction of the assembly line, described as starting in 1913 and having "Turned a craft-based economy into a mass-market one." 

As I recall from a long-ago history course, Eli Whitney pioneered the idea of the assembly line when, around 1790, he got a contract from the US government to produce the Whitneyville musket.  This weapon was revolutionary in that it was made from interchangeable parts.  Previously firearms were hand-crafted; the individual gunsmith had to machine each part to fit into the weapon he was making.  By introducing interchangeable parts, an unskilled workman could assemble the musket rather than having to rely on a skilled craftsman.  Without interchangeable parts, the whole idea of the assembly line would never have been workable.

After the jump, one more message on the hits and misses of our survey. 

What about beer? From a reader in the Midwest:

A breakthrough for early America which I think had global impact was the move from agriculture and into the early urban settings which, among other things, meant groups/communities were no longer subsistence based but that one group had to create things that supported and met the needs of others. America started having 'specialists' rather than self contained and self sustaining communities. Then, most dramatically, was the first Constitutional Convention of 1787 which eliminated the Articles of Confederation and generated a wholly new kind of inter-dependency.

And that struggling inter-dependency which led to America's economic growth and strength had its own dramatic breakthrough in the development and applications of Alexander Hamilton's notion of banking, credit and early capitalism/free markets to counter the European mercantile mode (in this, Jefferson's Barbary Wars might also be considered a global economic breakthrough). The centralization of debt by the federal government and the federal government's subsequent right to tax for common services and management also opened huge opportunities for entrepreneurs and the need by communities to integrate and further develop services and products.

One thing I was disappointed to see overlooked were several world changing military breakthroughs which then allowed cultures to forcibly intermingle, re-prioritize what needed to be done and mix intellectual capital. Two of those examples could include the English Long Bow (victory at a distance and with far less losses to the winning side) and mounted cavalry (allowing much wider range for military and social conquest). There was also the 'breakthrough' of so long ago when the first nomadic modern humans built structures and started to save and use seed linked, per some theories, to the brewing of beer thereby requiring crop growth.

From the original article itself:

Any collection of 50 breakthroughs must exclude 50,000 more. What about GPS systems, on which so many forms of movement now depend, and which two panelists recommended? What about the concept of the number zero...

The more questions and discussions our ranking provokes, the more successful the endeavor will have been.

Thus I declare success.