HISTORY116 - Evolution of the Human Diet

“What we eat,” “what we shouldn’t eat,” and “what we should eat” get a lot of play these days.  Many people think that much of the food that we eat today is harmful, causing obesity and health problems.  It made me wonder how we (as humans) got to this uncomfortable place.  So, I decided to investigate the subject.

This blog will cover the evolution of the human diet, from the time of the earliest humans to the present.  After a brief review of human evolution, to put the history of what we’ve been eating over the millennia in perspective, I’ll cover the diets of early human species, and then modern humans (homo sapiens).  I’ll highlight the beginning of eating meat, and controlling fire and the start of cooking - and talk about the impact on human evolution.  I’ll talk about the Agricultural Revolution, some dietary snapshots of early civilizations, the globalization of diets, the Industrial Revolution, and finally our modern diet and its unhealthy impact on life today, healthful eating, and the future of diets.

As usual, I will list my sources at the end.

Introduction:  Snapshot of Human Evolution

I thought it would be helpful to quickly review human evolution - to put the human diet timeline in perspective with evolving humans.  

Human evolution is the lengthy process of change by which people originated from apelike ancestors. 

The figure below shows the generally accepted human evolution tree, starting about 40 million years ago.  The several species enclosed in the green box are called hominids (orangutans, gorillas, chimpanzees, and humans).  The last common ancestor of hominids lived about 14 million years ago.

Evolution tree for humans, starting about 40 million years ago (Mya).

Hominids emerged in Africa, and were characterized by having no tail; a relatively long gestation period of 8 or 9 months; offspring born helpless, requiring extended care; and varying degrees of intelligence and cognitive capabilities.

From the figure above, the last common ancestor of chimpanzees and humans lived about 6 million years ago.  Humans are part of the so-called hominins (or hominini) group, and evolved through a complex series of changes over millions of years, beginning with the split from the chimpanzee lineage 6 million years ago. 

Most scientists currently recognize some 15 to 20 different species of early humans, including the perhaps familiar, homo erectus and homo neanderthalensis.  Human evolution wasn’t a linear progression, but rather a complex process involving evolutionary relationships among the different hominin species.  The only surviving species of this lineage is our species - Homo sapiens, which also emerged in Africa about 300,000 years ago.

Over almost 6 million years, early humans, before homo sapiens, adapted to bipedal walking; a more upright posture; enlarged chewing muscles; the ability to make simple stone tools for processing food, including meat; longer legs for long distance walking and running; larger brains; and finally, sophisticated tools for hunting.  Culturally, early humans began creating art, music, personal adornment, and rituals; engaging in symbolic burials and using decorative pigments; and building shelters and broad social networks. 

Early humans first migrated out of Africa into Asia probably between 2 million and 1.8 million years ago.  They entered Europe somewhat later, by between 1.5 million and 1 million years ago, followed much later by Australia and the Americas.  Anatomically modern humans began migrating out of Africa in waves, starting around 100,000 BC. 

Diet of Early Humans (6 Million Years Ago to 300,000 Years Ago)

In the earliest stages of human history, our diets were shaped by the foods available in the environment.  This hunter-gatherer diet, which lasted for nearly 90% of human history, was incredibly diverse and nutrient-rich, focusing on small wild animals, fish, insects, and a wide variety of natural plants, including berries, nuts, roots, and leaves - all of which provided vital nutrients.

The first major dietary change occurred at least 2.6 million years ago, the incorporation of meat and marrow from large animals.  This coincided with a shift to drier, more open grasslands in East Africa, making digestible plant foods less readily available, but providing an abundance of grazing animals.  Evidence suggests early humans used tools to butcher animals and access meat and marrow.  This dietary shift contributed to the development of larger brains and smaller guts.

Early humans started hunting large animals about 2.6 million years ago.

Early human hunter-gatherers ate raw meat - for over 5 million years!  Before the discovery and widespread use of fire for cooking (see below), that occurred much later in human history, raw meat would have been the only option available.

Hunter-gatherers maintained a higher level of physical activity and consumed a diet that was lower in calories than today’s average diet. This lifestyle likely contributed to lower incidences of diseases like obesity and diabetes, which are more common in modern societies.

Hunter-gatherers were also seasonal eaters, consuming foods based on what was available at different times of the year, a habit that inherently kept their diets varied and balanced.  The diversity in early human diets likely provided a broader array of nutrients, supporting a healthy metabolism and resilience against chronic diseases.

As early humans spread throughout Africa and into Asia, their diets diversified, utilizing a wider range of resources and ecological niches. 

The controlled use of fire for cooking dates back to at least 780,000 years ago.  Cooking made food more palatable and digestible, allowing early humans to access a wider range of foods and extract more nutrients - impacting human evolution significantly.  Cooking food is thought to be a key factor in development of larger brains and more efficient digestive systems.  It also allowed for migration into colder climates. 

Humans starting cooking food about 780,000 years ago.

Diet of Modern Humans (300,000 Years Ago to 12.000 Years Ago)

Like earlier human species, Homo sapiens were initially hunter-gatherers, and further refined hunting, gathering, and fishing techniques, exploiting a wide variety of plants and animals, including fish.  They developed a range of hunting tools, including projectile points.  As modern humans migrated across the globe, different groups adapted to diverse food environments.

Starchy plants like wild carrots, parsnips, and similar underground plants provided essential carbohydrates, and were likely a significant source of calories.  Depending on the season and location, various fruits and berries contributed vitamins and minerals to the diet.  Acorns, wild barley, and other seeds were processed and consumed, providing fat and protein.  Young leaves and edible flowers may have been consumed, particularly in times of scarcity.  In certain environments, aquatic plants like the yellow water lily were also part of the diet. 

As did earlier human species, homo sapiens hunted and scavenged animals, ranging from large mammals like bison and deer to smaller game like rabbits and birds.  Meat was a valuable source of protein and fat, contributing to brain development and increased energy levels.  Scavenging marrow from the bones of carcasses likely provided crucial fat for brain growth, predating extensive hunting practices.  In coastal and riverine areas, fishing played a significant role, providing additional protein and valuable nutrients, particularly docosahexaenoic acid, a type of omega-3 fatty acid that is crucial for brain health.

Insects like grasshoppers, beetles, and ants, along with their products such as honey, offered a readily available source of protein and other nutrients. 

Early modern humans developed sophisticated techniques to process and cook their food.  The discovery of starch grains on basalt maces and anvils suggests that tools were used to crush and crack plant materials like acorns, cereals, and legumes.  Cooking made tough plant materials more digestible and released more nutrients, especially carbohydrates, for the brain. 

Agricultural Revolution (12,000 to 10,000 Years Ago) 

The term "Agricultural Revolution" refers to the transition from hunting and gathering to farming, a process that involved the domestication of plants and animals, which occurred in multiple regions independently around 12,000 to 10,000 years ago. 

Independent domestication of plants in various parts of the world included (examples only): 

The Fertile Crescent (Middle East): Wheat, barley.

New Guinea: Taro, yams, and bananas. 

China (Yellow and Yangtze River valleys): Rice and millet. 

Mesoamerica: Maize (corn), beans, and squash. 

The Andes: Potatoes and quinoa.

West Africa: Yams. 

Wheat was first domesticated in the Fertile Crescent about 12,000 years ago.

As with domestication of plants, domestication of animals first occurred in various parts of the world.  Here are a couple of examples:

Sheep and Goats were domesticated in Southwest Asia, primarily for wool, meat, and milk production. 

Cattle and Pigs were domesticated in the Near East and South Asia; these animals provided food, labor, and materials. 

The Agricultural Revolution resulted from a combination of environmental changes (like the end of the last ice age) and cultural factors.  Cultural factors included increasing populations and competition for resources that may have spurred the need for more reliable food sources.  Agriculture offered a solution by allowing for production of surplus food, enabling communities to sustain larger populations.  The need for more food encouraged experimentation with plant cultivation and animal herding, driving innovation in farming techniques. 

The development of agriculture and the domestication of plants and animals marked a profound shift in human food production, including greater food security.  This allowed for population growth in more settled communities (and eventually villages and civilizations) and a more consistent food supply, but also introduced changes in diet and health, impacting nutritional health over generations.

This shift resulted in a less varied diet, compared to the hunter-gatherer diet, and increased the risk of nutrient deficiencies and health issues like tooth decay from increased grain consumption.  And people were at higher risk of infectious diseases in crowded settlements.

Dietary Snapshots from Early Civilizations

Concentrating on the Western World, here are a few dietary snapshots from early civilizations and the Middle Ages:

Sumer in Mesopotamia (5500 BC to 1800 BC): Sumerians relied on a diet primarily based on grains, particularly barley, which they used to make bread and beer.  They also consumed a variety of vegetables, fruits, and animal products, including fish and meat from domesticated animals. 

Ancient Egypt (3150 BC to 30 BC): The Ancient Egyptian diet was largely plant-based and included a variety of grains, fruits, vegetables, and legumes; with meat and fish as occasional additions.  Bread and beer were staples, alongside vegetables like onions, garlic, and lettuce; and fruits like dates and figs.  Meat, while enjoyed by the wealthy, was less common for the general population, who often relied on fish and poultry for protein. 

Olmecs in Mesoamerica (1500 BC to 400 BC): The Olmec diet was diverse, relying on both agriculture and hunting-fishing.  Key crops included maize, squash, sweet potatoes, and beans, with maize being a staple and central to their culture.  They also supplemented their diet with meat from domesticated dogs, fish, deer, migratory birds, turtles, and shellfish.  Additionally, they consumed cacao (source of chocolate), which was both a foodstuff and held spiritual significance. 

Ancient Greece (1200 BC to AD 600): The diet of ancient Greece was primarily based on simple, locally sourced foods, with a strong emphasis on cereals, olive oil, and fruits.  Legumes (beans, peas, and lentils), fish, and dairy products also played important roles, while meat, particularly red meat, was less common and often reserved for the wealthy. 

Roman Empire (27 BC to AD 476): The ancient Roman diet primarily consisted of cereals, vegetables, legumes, and fruits, with meat and fish being more common for the wealthy.  Bread was a staple, with wealthier citizens enjoying wheat bread, while the poor often consumed barley bread.  Olive oil, wine, and various cheeses were also integral parts of their meals. 

European Middle Ages (5th to 15th Centuries): The medieval European diet varied greatly by social class, but generally consisted of grains, vegetables, and dairy products, with meat and fish being more common for the wealthy.  Bread, often made from rye or barley for the poor and wheat for the wealthy, was a staple, along with vegetables like cabbage, onions, and beans.  Dairy products, including cheese and butter, were also widely consumed. 

Globalization

Almost from the beginning of human civilizations, food has been traded between peoples across the globe.  Globalization has profoundly impacted food systems by increasing food availability, and affordability, and providing varied diets through the spread of international ingredients.  Here are two major historical examples:

Spice trade (4000 years ago): The ancient spice trade, dating back 4,000 years, played a role in the globalization of food and culture.  The spice trade involved the exchange of spices across vast distances, connecting civilizations in Asia, Africa, and Europe for thousands of years.  Initially, land routes like the Silk Road (connecting China, Central Asia, the Middle East, and Europe) facilitated trade, but sea routes later became crucial, with Arab and Indian merchants playing pivotal roles.  Spices were highly valued for their culinary, medicinal, and preservative properties, and their trade significantly impacted economies, cultures, and even the exploration of new lands. 

Ancient spice trade routes.

Traded spices included ginger, cinnamon, cloves, saffron, cassia, cardamom, pepper, nutmeg, star anise, and turmeric - which were highly valued for their culinary and medicinal properties.

Columbian Exchange (15th and 16th centuries): The “Columbian Exchange” refers to the widespread interchange of plants, animals, culture, human populations, technology, diseases, and ideas between the Old World (Europe, Asia, Africa) and the New World (the Americas) in the 15th and 16th centuries, following Christopher Columbus's voyages.  Besides a major exchange of foods and diet, this exchange had other profound and lasting other consequences, including demographic shifts, ecological changes, and the spread of new diseases. 

The figure below shows many of the plants and animals that were introduced to different continents in the exchange.

The exchange of plants and animals during the Columbian Exchange.  Note also the transfer of Old Word diseases (lower right) to the Americas.

Since Columbus’s arrival in the Americas, the Columbian Exchange has slowed but not ended.  Shipping and air travel continue to redistribute species among the continents. 

Industrial Revolution (19th Century)

The Industrial Revolution (IR) was a period of major technological, socioeconomic, and cultural change, beginning in Britain in the late 18th century, and by the 19th century, to other parts of the world, including America.   It marked a shift from an agrarian and handicraft economy to one dominated by industry and machine manufacturing.  Mass production of food, as we understand it today, largely began during the 19th century, with the mechanization of agriculture and the development of the first techniques for large-scale food processing and preservation.  

In the 1800s, canning emerged as an efficient and reliable food preservation method. The primary preservatives used were traditional methods like salting, sugaring, and drying.  Vinegar and alcohol were also sometimes used.  While canning itself involved heat to kill microorganisms, it was the sealing of the containers that prevented recontamination.  Canning allowed for the long-term preservation of food, making it accessible beyond its usual season and geographic location, particularly for long-distance transport. 

The Industrial Revolution led to canned foods - convenient, but often containing preservatives to enhance flavor, extend shelf life, and prevent spoilage. 

Pasteurization also offered better preservation.   Louis Pasteur's discovery of pasteurization in the mid-1860s improved the safety and quality of various foods, particularly milk and beverages, by reducing harmful bacteria. 

American diets began to be altered, moving people from reliance on locally sourced, seasonal foods to a greater dependence on mass-produced, processed options.  This shift led to increased consumption of animal products, sugars, fats, and processed foods, while decreasing the intake of cereals and carbohydrates.  

20th Century to Present

Further advancements in food processing technologies, such as spray drying, freeze-drying, and the use of added preservatives, were developed to improve food preservation, packaging, and storage, leading to a wider variety of ready-to-eat meals. 

In the early 20th century (pre-WWII), the American diet was relatively rich in whole, unprocessed foods, with meals often prepared from scratch at home.  Staples included fresh vegetables, grains, and meats, with pork and beef being common choices.  Potatoes were widely available and inexpensive, often served as a side dish.  Beverage choices were limited, mostly consisting of occasional alcoholic drinks.  Processed and packaged foods began to emerge, offering convenience and longer shelf lives.  The food industry saw a rise in marketing and advertising, particularly in print and radio. 

The post-WWII era saw a significant rise in processed and convenience foods, including canned goods, powdered foods, and frozen products, fueled by wartime technological advancements.  TV dinners became symbols of modern convenience, reducing time spent on meal preparation.  The widespread adoption of chemical fertilizers and pesticides led to agricultural overproduction, making food readily available and often contributing to waste.  There was a shift toward a convenience-driven food culture, often at the expense of nutritional value.  Home appliances like refrigerators and freezers became more common, influencing food storage and preparation methods.  The rise of chain restaurants and fast food further altered eating habits, emphasizing speed and convenience.  Dietary guidelines began to be established, initially focusing on nutrient adequacy, and later incorporating prevention of chronic diseases. 

In the late 20th century through today, there was a dominance of ultra processed foods (UPFs), particularly sugar, white flour, white rice, and industrial seed/vegetable oils - high in sugar, salt, and unhealthy fats, and low in fiber and essential vitamins and minerals.   Moreover, trans fats were commonly found in processed foods like baked goods (cakes, cookies, pies, biscuits), fried foods (french fries, fried chicken), and some snack foods (crackers, microwave popcorn).  They were also present in some margarines, vegetable shortenings, and non-dairy creamers. 

There was also decreased consumption of unprocessed foods such as fresh fruits, vegetables, and animal fats (whole milk, butter, lard).  

All of this produced a rise in chronic diseases, including obesity, type 2 diabetes, heart disease, and certain cancers, linked to the overconsumption of UPFs.  There was a higher intake of added sugars and saturated fats, contributing to health risks like cardiovascular disease and obesity.

Modern American Diet

Unfortunately, today, the modern American diet is characterized by a high intake of processed foods, red and processed meats, sugary drinks, and a low intake of fruits, vegetables, and whole grains.  This dietary pattern is associated with various health issues and is a significant departure from what humans evolved to eat.

These changes in modern diets have been linked to increased rates of obesity, type 2 diabetes, cardiovascular disease, and other chronic health conditions, according to the American Medical Association. 

Large portion sizes are also a common feature of the American diet, contributing to increased calorie intake and potentially leading to weight gain. This has led to a normalization of larger portions, making it difficult for individuals to accurately gauge what constitutes a healthy serving size. 

Convenient and accessible fast food ((food that can be prepared quickly and easily and is sold in restaurants and snack bars as a quick meal or to be taken out) is also a significant part of the American diet, with a large percentage of adults and children consuming it regularly. 

Fast food is often high in calories, fat, sugar, and sodium, and low in essential nutrients.  Excessive fast-food consumption is linked to various health issues, including obesity, heart disease, diabetes, and digestive problems.  Fast food can displace consumption of nutrient-rich foods like fruits, vegetables, and milk, leading to potential nutrient deficiencies. 

The modern American diet contains too many unhealthy foods.

Also, fast food can be habit-forming through cravings due to its impact on the brain's reward system.  Fast foods are often engineered to be highly palatable by combining sugar, fat, and salt in proportions that are highly rewarding to the brain.  Eating these types of foods triggers the release of dopamine, a neurotransmitter associated with pleasure and reward, in the brain's reward circuitry.  The pleasurable sensation from dopamine release reinforces the behavior, making individuals more likely to seek out and consume these foods again, creating a cycle.

In addition, globalization has made foods from around the world more accessible, allowing people to enjoy diverse cuisines and flavors.  While this trend has promoted cultural exchange and dietary diversity, it has also contributed to the spread of Western-style diets rich in fast food and processed ingredients.

Alcohol also plays a role in the American diet, particularly in social settings and at mealtimes, though the prevalence and consumption patterns can vary.  Wine, beer, and cocktails are all enjoyed with meals at home and at restaurants.  Alcohol consumed before or with a meal may stimulate short-term food intake.  This might be due to reduced satiety signals or by increasing the rewarding value of food through its effects on the brain's reward systems. 

Health-Conscious Eating

A growing number of people today are becoming health-conscious and are returning to nutrient-dense, whole foods.  Healthy dietary trends prioritize natural, minimally processed foods.

This movement is driven in part by research highlighting the benefits of plant-based diets for both personal health and the environment.

Health-conscious eating involves making deliberate food choices with a focus on nutrition and well-being.  It's about understanding how your food choices affect your health, the environment, and society.  This approach emphasizes whole foods, balanced meals, and slowing down to savor each bite. 

Numerous healthy diets are available today, catering to different individual health goals and preferences.  

Here are some key components of a healthy diet:

Emphasize fruits and vegetables: aim for a colorful plate with plenty of fruits and vegetables for essential nutrients and fiber. 

Choose whole grains like brown rice, quinoa, and whole-wheat bread over refined grains. 

Incorporate lean protein meats, poultry, fish, beans, eggs, and nuts into your diet. 

Limit saturated and trans fats: reduce intake of red meat, processed meats, and fried foods. 

Control sodium and sugar intake: be mindful of added sugars and salt in processed foods. 

Stay hydrated: drink plenty of water throughout the day. 

Consume alcohol in moderation.

Key elements of a healthy balanced diet - prioritized from bottom to top.

Future Human Diet

The future human diet is likely to involve a greater reliance on plant-based foods, alternative proteins, and sustainable food production methods.  This includes an increased consumption of fruits, vegetables, legumes, and nuts, alongside a shift away from excessive amounts of red meat and sugary products.  

The need to reduce reliance on traditional livestock farming is driving interest in alternative protein sources. This includes: 

Edible insects like crickets and mealworms - a sustainable source of protein and nutrients. 

Lab-grown meat offers a way to produce meat without the environmental impact of traditional farming. 

Seaweed and algae are sustainable sources of protein and other nutrients, and can be grown in various environments. 

Alternatives like these can reduce environmental impact while meeting the protein demands of a growing population.

“Your diet is a bank account.  Good food choices are good investments.” - Bethenny Frankel (American entrepreneur, television personality, philanthropist, and author)

Sources

My principal sources include: “Six Million Years of Human Evolution,” naturalhistory.si.edu; “Timeline of food,” wikipedia.com; “The Evolution of the Human Diet Through Time,” jrfood10.com; plus, numerous other online sources.  I am increasingly, and hopefully carefully, using Google’s AI Mode summaries of searches, including for this blog, queries about all the major elements of the outline of the article.