If you love those naughty high-carb foods that are high in sugar and bad for your heart, now you’ve got someone to blame.

Ancient pre-humans.

A recent study in the journal Science offers a reminder that so-called good carbs were a dietary staple that helped our ancestors survive in a harsh world. It also serves as a reminder of the kinds of carbs that won’t clog your arteries.

Scientists found that present-day humans have a rich variety of a gene called AMY1. They say the more AMY1 genes you have, the more carbohydrates your body can digest.

An analysis of ancient DNA also showed that these carbohydrate-friendly genes emerged long before the advent of modern society’s so-called “bad carbs.” Think chocolate, ice cream, and pasta.

In fact, the study traced the gene back at least 800,000 years in our evolutionary lineage, long before homo sapiens emerged from the African savannah. The duplication of these genes so long ago supports the idea that they helped humans digest wild grains.

Humans transitioned from being exclusively hunters and gatherers to farmers starting roughly 10,000 years ago. That transition was eased by this ancestral genetic foundation.

Not all carbs are unhealthy. Good carbohydrates are unprocessed foods that keep body sugar and weight low. They’re rich in vitamins, minerals, and fiber and include legumes, starchy vegetables, millet, and oats.

Processed foods high in carbs, however, can lead to diabetes or heart disease.

The study provides insight into the role of genetics in shaping the modern diet and a lesson that the past is prologue — except that our ancestors would have been hard-pressed to find a donut shop.