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Humans & Carbs: An Evolution

  • Writer: Timothy P. Smith MS, RD, LDN
    Timothy P. Smith MS, RD, LDN
  • Jul 7
  • 3 min read

Many people will describe a "Paleo Diet"as high in protein and fat, and very low in starch. As if cavemen lived on nuts, berries, and vegetables. Unfortunately for these groups, recent evidence suggests that humans are genetically hardwired to use carbohydrates (starches specifically) for energy — and it appears we have been for over 750,000 years.


"Ugg like tato."
"Ugg like tato."

A groundbreaking study published in Science used advanced genome-mapping techniques and sequenced 98 modern and 68 ancient DNA samples to trace when humans evolved multiple copies of the AMY1 gene, which produces salivary amylase—the enzyme that begins starch digestion in the mouth.


The results were remarkable: Hunter‑gatherers from Eurasia, as well as Neanderthals, carried 4–8 copies of AMY1, indicating starch digestion ability existed well before farming began. Some of the samples were 45,000 years old.


Then around 10,000 years ago, with the agricultural revolution, copy numbers rose further, as humans began eating more cultivated starches like grains and tubers.


This ancient adaptation may explain why many people today feel a powerful craving for carb-heavy foods like potatoes, bread, and pasta—our bodies have hardwired expectations for energy from starches.


🧬 Why Our Bodies Crave Carbs (But Should Be Careful)


While our genes evolved to handle complex carbs from natural sources, the rise of ultra‑processed carbohydrates in modern diets has outpaced our ability to moderate ourselves. These calorie-rich, low-fiber foods now overwhelm our collective blood sugar and contribute to diabetes, obesity, and related metabolic disease.


Historically, carbohydrates from wild plant sources—fruits, tubers, seeds—were seasonal and supplemented by protein from game. The modern diet, in contrast, floods the system year-round with refined grains and sugars, pushing obesity and type 2 diabetes rates sky-high, especially in Western lifestyles.



✅ Starches: Friend or Foe?


  • Essential energy: Glucose (from starches) fuels the brain, red blood cells, and plays a role in virtually all cellular processes, including in the thyroid.


  • Gut health support: Dietary fiber—an indigestible carbohydrate—feeds beneficial gut bacteria and supports immune, mental, and metabolic health. These fibers often come from starches, such as wheat or potato skin.


  • Mood & cognition: Carbohydrates can positively affect alertness and emotional balance. However, excess refined sugar/starch consumption may lead to mood swings or outright fatigue.


  • Chronic disease risk: Persistent overconsumption of processed "simple" carbs seems to play a central role in metabolic syndrome, cardiovascular disease, and chronic inflammation. But consuming too little starch can contribute to hypoglycemia, reduced lean body mass, and potentially thyroid issues.



As always, we come back to The Golden Rule of Nutrition: "Everything in Moderation."



🍽️ Nutrition Takeaways


1. Focus on quality over quantity


Choose whole grains, legumes, vegetables, fruits, and unprocessed tubers (with the skin) over refined or sugary carbs. Fiber-rich complex carbs help regulate blood sugar and support gut health. Most people should aim for 4-6 servings per day, each providing approximately 15 grams of carbohydrate.


2. Balance your plate


Modern dietary guidelines recommend that carbohydrates should account for 40–65% of daily calories, with priority on low‑glycemic and high‑fiber sources.


3. Listen to your genes…but be intentional.


Your body may strongly crave starch—but balance it with lean protein, healthy fats, and fiber. This helps you to get the starch you need, while averting blood sugar spikes.


4. Support gut health


Include fermentable fibers and resistant starches, together, to nurture a healthy microbiome—essential for reducing inflammation, supporting immunity, and improving your odds of living a long, healthy life.



Final Thoughts


Human biology has been "tuned" to crave and efficiently digest carbohydrates, thanks to evolutionary adaptation over hundreds of thousands of years. But our modern diets—overly rich in refined starches and sugars—do not align with that ancient design.


By intentionally choosing whole, fiber-rich carbs and balancing them with animal proteins and unsaturated fats, we can harness the benefits of almost 1,000,000 years of human metabolism without falling into its traps.


Tim Smith MS, RD, LDN


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Citations:


1. Yilmaz F, Karageorgiou C, Kim K, et al. Reconstruction of the human amylase locus reveals ancient duplications seeding modern‑day variation. Science. Published online 2024. doi:10.1126/science.adn0609 elifesciences.org


2. Perry GH, Dominy NJ, Claw KG, et al. Diet and the evolution of human amylase gene copy number variation. Nat Genet. 2007;39(10):1256‑1260. doi:10.1038/ng2123. PMCID: PMC2377015


3. Fellows Yates JA, Velsko IM, Aron F, Posth C, Hofman CA, Austin RM, et al. The evolution and changing ecology of the African hominid oral microbiome. Proc Natl Acad Sci U S A. 2021;118(20):e2021655118. doi:10.1073/pnas.2021655118


4. Pajic P, Pavlidis P, Dean K, Neznanova L, Romano R‑A, Garneau D, Daugherity E, Globig A, Ruhl S, Gokcumen O, et al. Independent amylase gene copy number bursts correlate with dietary preferences in mammals. eLife. 2019;8:e44628. doi:10.7554/eLife.44628. PMCID: PMC6516957


 
 
 

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