Genome science has made stunning advances in the past few decades. But until recently, no one had tried to sequence Sequoia sempervirens, the coast redwood. Part of the problem was the species’ complexity. Humans are “diploid,” meaning that for each chromosome, they have one copy inherited from their mother and one from their father. Redwoods, on the other hand, are “hexaploid,” meaning that they have three copies from each side, which triples the size of their genome.