After consulting my doctor, I’ve recently started upping the “good” fats to my diet. (I love half an avocado on toasted sourdough!) Nuts are great source of monounsaturated fats, so I’ve been indulging in a few nuggets of my favourite — macadamia nuts. Little did I know, that what I thought was simply a healthy snack, was actually a wonder of modern agriculture!
Hawai’i is the centre of macadamia nut production, growing a whopping 70% of all macadamias eaten on the planet. Back in May, researchers reverse-engineered the genome of a sample of Hawaiian trees and compared them with trees still grown in the macadamia’s natural habitat of Queensland, Australia. The Hawaiian trees had a very narrow set of genetic markers, which indicated that the majority of the world’s macadamia nuts are descended from a single tree or stand of trees in Queensland.
“‘A small collection of seeds were taken to Hawai’i at the end of the 19th century and historical records suggest that there was maybe six trees grown from that sample of nuts that were taken by Robert Jordan and planted in his brothers’ backyard in the suburbs of Honolulu in 1896,’ [horticulturist and study author Craig] Hardner told ABC News.”
From this small sample grew the entire Hawaiian macadamia population! But such focus comes with a price: Like many other food crops, macadamia nuts are propagated by grafting. The limited genetic diversity of the Hawaiian macadamias is a result of this process — effectively, the trees are all clones of the original Queensland “parent.” This also means that, like other monoculture crops, the majority of macadamia trees could be wiped out by a badly-timed blight or disease.
Thankfully, despite a small natural range, the Queensland macadamia trees exhibit a greater range of genetic diversity and should stand fast in the face of a blight if we humans don’t catch it in time. I take this as an object lesson in the limits of human interference in nature. And in responsible snacking!