IEEE Senior Member Nick Patterson says he’s always enjoyed taking on a challenge. After spending much of his career as a mathematician doing classified cryptographic work for both the British and U.S. governments, and then applying his mathematical insights to the stock market, Patterson is now trying his hand at one of the greatest challenges of all: decoding the human genome.

For the past six years, he has been at the Broad Institute in Boston, a joint research center of Harvard and MIT, where he’s been analyzing human, chimpanzee, and gorilla genomes in a quest to better understand the evolutionary split between human and chimpanzee ancestors. That research was published in a groundbreaking study published last May in the journal Nature. And now Patterson is working to get funds to study the evolution of other primates.

The published study suggests that about two million years after human and chimpanzee ancestors split, and stopped breeding with each other, the two groups may have interbred again before a final parting of the ways. It’s a startling discovery, because scientists have long believed that human and chimpanzee ancestors split once and went their separate ways.

“The findings were surprising, and really quite remarkable,” says Patterson, who, because of the study, was featured in an article in The New York Times in December. “I like to say we’re all walking around with our history inside of us,” he says.

BREAKING LIFE’S CODE How did a mathematician get involved in studying evolution? It’s all thanks to a lecture about human genetic history that Patterson attended in 2001 at the Broad Institute. The topic so engaged him that after the lecture he approached the speaker and said, “I want to work with you.”

The speaker was David Reich, an assistant professor of genetics at Harvard, who later directed the human and chimpanzee genome study. It wasn’t long before the two were working together at the institute, researching disease genetics and population structure. In 2002, Patterson and Reich turned their attention to the evolutionary split between human and chimpanzee ancestors.

Whether it’s analyzing DNA or decrypting code for the intelligence community, “it’s all data,” Patterson explains.

Reich, Patterson, and three other researchers analyzed millions of DNA sequences, which are delineated by a succession of four types of molecules called DNA bases. It is the sequence of these bases that encodes genetic information. That’s where Patterson’s ability to analyze large sets of data came into play. He used computer algorithms to compare chimpanzee, gorilla, and human genomes and count the DNA bases that differ from each other.

At one point, “we all had the same bases,” Patterson continues. Through evolution, these bases mutated, leading to different species. Because such mutations occur at a certain rate, Patterson and his colleagues used the data to estimate how long ago the two species stopped breeding with each other. But DNA bases can mutate more than once, so Patterson also created equations to estimate how often such mutations occurred. The researchers revised the computer algorithms to accommodate this new data, and the result was “a big surprise,” Patterson says.

Although scientists had believed that the split between human and chimpanzee ancestors occurred about 7.5 million years ago, the researchers found that while some human and chimpanzee ancestors did split at that time, others split about 5.4 million years ago. “It was a surprisingly large gap,” Patterson says—one so large that it suggested that the two lineages might have interbred again after initially splitting off.


A NATURAL COMPETITOR Born in London in 1947, Nicholas Patterson became interested in math as a teenager. “I was competitive and successful in math,” he recalls. He went on to get a bachelor’s degree in mathematics in 1968, and then earned his master’s and doctorate in the same discipline in 1967 and 1974, respectively, all from Cambridge.

In 1972, Patterson began work as a mathematician at the Government Communications Headquarters (GCHQ), a British intelligence agency that breaks codes, in Cheltenham, England. His work there remains classified, but there is one thing Patterson can talk about: the priceless learning experience he had.

“More important than working as a mathematician, I learned about statistics and data analysis there,” he says. Through mentors at the GCHQ, Patterson became acquainted with the mathematical philosophy of Alan Turing, “a dominant intellectual force” and the mathematician whose team decoded German messages during World War II at Bletchley Park, where the code-breaking intelligence agency used to be housed.

“Turing really reinvented statistics,” Patterson says, referring to Turing’s work on Bayesian statistics, which holds that probability depends on an opinion about the odds of something happening, and that the opinion should be updated as new data comes in. That philosophy was controversial in the 1970s, but Patterson says Bayesian ideas have been useful to him throughout his career.

In 1980, Patterson moved across the Atlantic to take a job as a cryptographer at the Center for Communications Research, a branch of the Institute for Defense Analyses, in Princeton, N.J. After 13 years of classified work there, Patterson joined Renaissance Technologies, a hedge fund in East Setauket, N.Y., where he analyzed data related to commodity futures and stocks. In 2001, he moved to the Broad Institute.

The results of the institute’s study have inspired Patterson to continue his genetics work. Patterson and Reich are currently focusing on disease genetics, working on a shortcut for scanning the genome to find genes that cause disease. They’ve already found a region of the genome implicated in a risk for prostate cancer.