Illustration by Angelika Manhart
I knew I wanted to be a scientist when…

Random Drift

By Idan Efroni

I knew I wanted to be a scientist when I was just a boy, gazing upon the distant stars and…

Wait, no. That’s not me. That’s Carl Sagan.

My journey into science might never have happened if two planes hadn’t crashed into the World Trade Center in 2001. I was almost 6,000 miles away on that day, working as a computer programmer in a startup I founded with a friend in Tel Aviv. We were developing mapping software for a big client in Albany, NY and were finalizing a new version we had planned to release the following month. It was the end of the work day. I had a date planned with a sweet journalist I’d recently met.

“Open CNN!” My partner rushed into the room. News websites crashed within minutes. We were frantically refreshing our browsers. I didn’t make it to the date.

In the chaos that followed, our contracts were cancelled. Without income, we were forced to sell the furniture (though I still have one of the chairs), shut down the computers and close the door on our company. I was 27 years old.

Charles Darwin had little room for randomness in his theory of natural selection. Adaptation was a precise artisan: there were birds with different beaks, and those with better beaks had more offspring. Darwin was out to find the ruling order in biology. He was, lest we forget, a Victorian. For a long time, adaptation was the sole driving force behind evolution. Everything had to have a reason.

But randomness has found its way in. Organisms die all the time. The bird with the best beak can be hit by a falling rock — just like that, removed from the gene pool. It was the American scientist Sewall Wright who realized that random events are a strong force in evolution. He called this effect “random drift.”

Closing the company freed me to change course. I enrolled in university, majoring in philosophy. Just before the year started, I added biology as a second major, causing some bureaucratic mayhem at the registration office. “It’s more down-to-earth,” I explained.

Much more than I realized, though, biology was full of adventure and open questions. I continued to a Ph.D. in developmental genetics (and married the sweet journalist).

I was trying to understand how leaves know when to stop growing, and how do they know what size to reach. Working on a mustard-like plant, we found out that if you inactivate several genes, its leaves just kept on growing, for months and months, to more than 10 times their normal size. I wanted to know why.

I had entered the field just as it was beginning to explode with data. Techniques were available to discover which genes were active at every stage of development. We thought that the more we knew about when particular genes are active, the more we’d be able to understand the organizing principles controlling the growth of the leaf.

But the exact opposite happened. Just like the leaves I was studying, the amount of data kept growing, and the more we got, the more chaotic it all seemed. Many of the genes were turning on and off with no apparent reason or clear pattern. Leaves that looked almost alike could have a completely different set of genes active in them. It took some time to find “anchors,” or genes that were always there. But I remember looking at the data and realizing what it meant: there was no one way to control the size and shape of a leaf – there were endless genetic paths.

We humans like certainty. Our curiosity is only really satisfied by a well-connected causal chain. And every once in a while, when running an experiment late at night in the lab, or waiting at the airport gate on my way from one conference to another, I try to trace back my path to becoming a scientist. Sure, I can see the choices, the reasons, and the inclinations that led me along the way. But I also see the random events, the near-misses and the “what-ifs.” Could I have been doing something else? Sure. Would I? Not in a million years.


Idan is an Assistant Professor at the Hebrew University, Israel and a Howard Hughes Medical Institute International Research Scholar. He often claims to be unpredictable, but his teenage daughters disagree.