The paragraphs go by much faster than the learning did. If you let each paragraph equal a day, or a week, or maybe even five years of our own process, alternately scrambling like mad and sitting back soaking it all in–then you might have just about the right scale.

Kate Keller’s genius invention of the time claps was partly about time, but also about scale: using the small as a window on the huge. Of course, sometimes we make scale models in which something made large is used as a window on the small–much larger models of the DNA helix, for example. But here, we were definitely trying to grasp huge, and the time clap model was a way to compress very long periods of time into periods of time we could experience.

The time claps were also about changing the scale. The 5,000,000 years of hominid evolution we considered for the first time clap (and the previous post) are a drop in the bucket compared to the history of life, or an infinitesimal speck compared to the history of our universe, which we only waved at. Hello, history of universe, we are breaking off a tiny chunk of you, which seems enormous to us.

Five million years is one hundred times as long as the 50,000 years of our own species’ wanderings across the continents. When our class went from the first time clap to the second, we were thinking about one-hundredth as long a stretch of time all together, and each clap was worth one-hundredth as much time as before.

Our species had been around for a while before some of us took the chance of leaving Africa, almost certainly unaware that we were switching continents, but meeting considerable challenges to expand our territory. Following Spencer Wells’s account, based on research with Y chromosome mutations, we tracked our way from continent to continent.

At each stage, through weeks of learning, we investigated some of the remaining indigenous peoples, again following Wells’s lead and using his video, The Journey of Man, in which he visits Aboriginal Australians, people from remote villages on the Indian subcontinent, central Asians, Chukchi people from eastern Siberia, and Navajo in North America.

The time clap itself was a way to summarize what we’d learned: about genetics, about the challenges of human expansion into new environments, about ways the human body had evolved to handle those new places.

Clapping and counting together–clap, two, three, four–we let each four-second interval, each clap, be worth 500 years. Each student, or a pair, was responsible for moving onto the map at the right time, and placing one of our crepe paper streamer lengths. He or she placed one end in the area where that y-chromosome mutation is thought to have arisen, then carried the streamer following a simplified, summarized version of that mutation’s spread.

We worked hard to figure out all the logistical problems in showing these things. Here’s a detail from the photo I used in an earlier post, so you can see that Russell is poised to do his job as the time line person, responsible for showing at each clap where we were on the time line. The pieces of brown paper on the floor are continents.

I folded the first section of this time line, so I could show two labels almost in focus.

Here’s a detail from a map in The Journey of Man. which we used as our way of timing the spread of groups of Homo sapiens across our own paper continents. Each arrow is a schematic representation of the spread of the  y-chromosome mutations that have let scientists reconstruct this sequence of expansions.

Here’s the map key that helped us connect mutation numbers with times in our time clap and on our time line:

Because I’m a nearly total failure at throwing things away, I still have some of the crepe paper streamer lengths we cut and used to represent the paths. The photo below shows two rolled-up streamer lengths for M130. These were placed beginning at the northern end of the short length for M168 (the Y chromosome shared by all men not indigenous to Africa.)

One student carried one of the M130 streamers by the coastal route around the Indian subcontinent, and then through southeast Asia to Australia. There was much less water to cross, in the time this happened, because the sea level was so much lower, with lots of water locked up in ice. Much more of southeast Asia and the nearby islands stretched in one long continuous land mass. But still, there were many miles of open ocean to cross, to get to Australia. Somehow people did it, spreading around the perimeter of the Indian Ocean astonishingly quickly.

Another student carried the second M130 streamer northeast to Siberia and then to North America–a very long expansion into harsh conditions, that took a much longer time.

This whole field of human population genetics is moving fast. M130 is now designated as C-M130, and on Wikipedia you can find an excellent, very technical article about the C-M130 lineage, or haplogroup. I love the labels on these streamers, made by students, full of pride in their own technical knowledge at that point.

I’m not sure about this streamer with its many colors, mutation group leading to subgroup, leading to further subgroup, but I think it has the earliest journey on the outside: out of Africa leading to the Middle East, to south central Asia, to central Asia, to Siberia.

If you want to start a fight at a meeting of the folks who pay attention to such things, just ask about how we arrived in the Americas. Increasing numbers of  scientists now say that boats must have been involved, small boats made probably out of walrus or other large marine mammal skins stretched over frames, like the ones coastal Chukchi people still make and use. Spreading across the northern edge of the Pacific Ocean west to east, we probably kept fairly close to the coastline or ice pack, and in each new venture moved only far enough to come to an ice-free coastal area that had what we needed. Alice Roberts describes her own take on this in her video called The Incredible Human Journey.

Because of lower sea levels at the time, that ancient coastline is far out to sea now. Boats wouldn’t last to be found, and coastal settlements would currently be under many feet of water–so there’s not much archaeological trail of any kind, so far. The evidence is all circumstantial: somehow we arrived in places that involved crossing wide stretches of water, no matter how low the sea level had dropped.

However they did it, some very small percentage of my own ancestors made that ancient journey into North America. Still, that’s not why I say “we.” I’ve come to feel that all of this story belongs to all of us.

The rest of the ancestors of our class (including most of mine, and Kate’s) came to North America more recently. We wanted to end this thematic study of who we are and how we got here by learning about our recent immigrant ancestors, and the patterns of goodbye and hello that shaped their lives.

So we changed the scale again. In our preparations for the third time clap, we looked at just the last 500 years of immigration to North America, and focused on stories we had gathered, about people related to us and about family friends. Those included Pilgrims who traveled on the Mayflower, representatives of the huge influx from eastern and southern Europe in the early 20th century, and more recent immigrants from Latin America, some with mixed African heritage.

For this time clap we made a very simplified geographical representation that could fit in our classroom. Simpler props–but we were moved and focused by representing individual real people whose stories we knew. Clapping and counting, holding signs, we showed their individual arrivals decade by decade.

What do Kate and I think about, looking back at all this?

I often recall a memory that is uneasy. A girl who had been adopted from China represented herself in our third time clap, and “traveled” east to North America. She joined us from another class, and we were proud and excited to have her take part. Only afterwards, and with regret, I realized that she was embarrassed, unhappy to have been identified as a recent immigrant.

Kate remembers worrying that we were all focused so intensely on our parts in each time clap’s execution, struggling to move and do the right things at the right moment, that it was hard to pay attention to the whole as it happened around us. At least for us, for Kate and me and the invaluable parent volunteers who helped us pull it off, each of those not-quite-seven-minute stretches went by in a blur. So we might be tempted, doing it again, to change the scale and make each time clap last longer, not in what it represents but in how long it takes in the present. Of course, then we might lose people in the long stretches with not much happening. Trade-offs. Probably we’d let the kids decide.

For sure, the value was not so much in the observed performance, but in the experience from the inside–all the preparation, and that immediate sense of taking part in something huge.

Lucky-and-a-half, both grown-ups and students, we felt like explorers ourselves, opening up new knowledge, sharing that with our families and with each other, imagining eyes focused on new horizons.