A Conversation with 23andMe’s Ivan Juric

This interview is part of an occasional series of profiles introducing you to some of the scientists at 23andMe. Ivan Juric Ivan Juricstudied molecular biology at the University of Zagreb, Croatia, and went on to get his PhD in ecology and evolution at the University of Tennessee.

He did his postdoctoral work in the Graham Coop lab at the University of California, Davis where he did analysis on population genetics, specifically on Neanderthal introgression in humans. Here at 23andMe Ivan works on our research team and is continuing his work on Neanderthal and other ancient human populations.

Tell us about your education:  

I grew up I went to elementary and high school in Zagreb, Croatia. Zagreb is the country capitol and the biggest city in Croatia. Schools in Croatia differ from US schools somewhat. For example, we had morning and afternoon shift. This means that, starting at the age of 6 and until I started college, one week my school would start at 8am and last till 1pm and the next week it would start at 1 and finish at 7pm.

Only recently I realized that schools in the US start at the same time each week. So weird! I went to high school that was known for its strong math, computer and natural sciences program. I was not really interested into solving equations or coding, but that is what my friends did, so I did it too. I loved biology tho. My biology teacher had his office converted into fruit fly genetic lab where he kept 10 or so different drosophila mutant lines. This is how I got introduced to genetics – by doing drosophila crosses. So, at least in part, I’ll blame him for choosing to study molecular biology at the University of Zagreb.

Unsurprisingly, undergraduate program in Croatia is bit different compared to US. Our classes are more specialized. For example, during the course of my study I took over 40 biology related classes some covering really obscure details that not many care about. But we had no history, social science, language or art related class. One of those 40 biology classes was population genetics, which was a mix of math, biology and computer science, and obviously I liked it. During my junior year I spent a summer at the University of Tennessee, USA in the lab of Sergey Gavrilets. Sergey is known for his theoretical work on speciation and I enjoyed my stay at UTK, so after I finished my undergrad I went to study with him.

Some years later, I got my PhD in ecology and evolutionary biology from UTK, and went to do a postdoc at Davis, CA in Graham Coop’s lab. There I stayed one year and studied selection against Neanderthal ancestry in modern-day humans. Then I joined 23andMe.

Ivan Juric, Computational Biologist and Population Geneticist

Originally from: Zagreb, Croatia

Education: PhD: Ecology and Evolution, University of Tennessee

Post Doc: Graham Coop’s Lab, University of California, Davis

Fun Fact: “I had to look up what 23andMe’s name meant.”

What’s your job title and role here at 23andMe?

My title says “Computational Biologist, Population Geneticist,” but I had to search the company directory to dig that out. It’s not that we hide our titles here, but I don’t really use my title often (like ever, except in formal documents), so I forgot what it is. I think that this says a lot about the company, and why I like working here. I am part of ancestry team in our research department.

At 23andMe I just do what I’ve always been doing, which is to find a problem I can solve and then solve it. It just happens that problems I find interesting are the problems others at 23andMe think are worth solving. For example, I proposed a new method for finding relatives using DNA data during my job talk and now I am working on it. This method might have been something I would be working on if I had stayed in Graham’s lab. So, to sum up, I get to do things that I find interesting and make me happy, I get paid for that and what I make is useful for people who pay me. Can’t beat that.

What were you researching before you came to 23andMe?

While I was at Tennessee, I studied how population history and structure affects how some populations, and how those populations diverge into distinct species. My work was theoretical – learning about speciation by solving equations and running simulations. One can learn a lot about general patterns during speciation process this way. In Graham Coop’s lab at UC Davis I studied the details of human and Neanderthal intermixing. We developed a model that enabled us to estimate the average strength of selection against Neanderthal ancestry in modern-day humans. Then we used the publicly available data to estimate how much Neanderthal DNA was selected against.

It turns out that the offspring of pairings between humans and Neanderthals were on average not really successful at passing on their genes to future generations.  Even so, enough of them survived that that people of European and Asian ancestry still have some Neanderthal DNA. It would be interesting to understand better why some early human-Neanderthal hybrids managed to pass on their genes. It Might be because among many deleterious Neanderthal alleles, those lucky hybrids had few alleles that were beneficial. However, it might also be because those hybrids appeared in very small populations where selection is weaker. We don’t know yet.

What are you working on now at 23andMe?

I am currently developing new methods for improving our DNA relative’s tool and Ancestry Composition report that will offer finer and more detailed results. More generally, I’m working on different projects dealing with “IBD”, which stands for “identity by descent”. DNA segments that are IBD between two individuals are important because they contain information about their genealogical relationship. For example, close relatives will share longer IBD segments than distant relatives. By looking at the patterns of IBD sharing between different individuals, we can learn a lot about how related they are.

Why are you excited about genetics?

Many problems in genetics can be represented using mathematics. Often, these genetics problems are mathematically equivalent to flipping coins, or shuffling a deck of cards, or finding the fewest number of airplanes to visit many different cities, or describing seating arrangement in a Chinese restaurant. I find that fascinating! This means that when I feel like it, I don’t really need to study genetics to do genetics. It’s enough to find a more interesting process that follows the same rules as my genetic problem, and study that other process instead. That way of thinking makes my work always interesting. Just think about it, instead of solving really annoying problem, I’m just trying to count how many people are eating around me in my imaginary restaurant (which serves only the best food and is decorated in the best possible way). Next day, I might be planning flights to Hawaii while trying to solve another annoying genetic problem. Genetics never gets boring.

Tell us about one of your interesting findings at 23andMe, or in your previous scientific life.

We were able to use our model to show that early offspring of intermixing between Neanderthals and humans were likely to have been unfit for survival – very few flourished.  That was a really neat result. But for me personally the best moment in that project was when I realized that some equations I came up with were mathematically equivalent to equations published in a book chapter 30 years ago by a scientist studying gene flow, which is a genetic term for how genes pass from one group to other. His work looked at how gene flow might impede speciation, or the process by which populations evolve to become distinct species. Some people might freak out when they find their equations already published, but I was very excited because I could link my work to previous one.

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Tell us about a recent breakthrough in genetics research that you think will have a big impact on the industry.

I’ll go with the safe ones. Lowering sequencing cost and CRISPR. Soon sequencing will be cheap enough and it will make sense to sequence whole genomes rather than genotype a subset of SNPs. This means that we’ll have more data to work with. Hopefully, we’ll find something new! Cheap sequencing will also change industry since we’ll need to figure out an efficient way to store and quickly analyze this data. Apart from that, genetic editing, in the form of the new technology based on CRISPR-Cas9 allows us to change genes cheaply. This is important if you want to understand how those genes work. A great way to figure out how genes work is to break them and see what happens. With CRISPR it’s much easier to break specific genes.

One interesting fact people don’t usually guess about me is:  

I always tell great jokes. If you disagree, you have no sense of humor.

Did you learn anything interesting from your 23andMe results? Did you make any changes as a result of taking the test?

My wife reserved “my” 23andMe kit for herself. That’s what I learned.

What’s one thing the average consumer should know about genetics?

I find that many are confused with concept of stochasticity, which is very important concept in genetics. Scientists are in part to blame for this confusion, because we often say that an outcome occurred “by chance.” The argument is then that an outcome can’t happen “by chance,” but rather that it happened “for a reason.”  The opposite of “stochastic” is not “for a reason” but “deterministic.” Tossing a coin is an example of a stochastic process. I know why and how a coin landed on heads, but the next time I toss the same coin, it might be tails.

A deterministic process is one in which there is no randomness, such as tossing a rigged coin that always lands on head side. So next time you hear a geneticist saying that something happened “by chance” just think of tossing a coin.