Eating more meat made us human. Now our survival demands we eat less of it.

How did we become human? I’m not talking about primitive Homo sapiens, I’m talking about the recognizable humans we think of today, ones with expansive languages, cultures, and social dynamics.

You might think the answer is the simple, straightforward one we’ve all heard before, the answer repeated in mythologies around the world: Fire.

Fire lit up the night and allowed us to stay awake longer, telling stories and constructing tools. It kept us warm in cold climates and warded off predators who might otherwise sneak into our encampments for a late-night snack; it allowed us to harden the tips of our spears and become more effective hunters.

And while fire played a significant role we should never underestimate, science points to another catalyst of human progress: Meat.

Today, I see many people, particularly environmental activists and die-hard vegans, shaming people for eating meat. They say it’s immoral and needlessly cruel. And maybe it is. I don’t know.

However, I do know that it’s all too easy to dismiss the benefits of meat when you live in an era where a vast variety of vegetables from around the world are easily accessible in grocery stores down the street, not to mention genetically modified to produce bigger yields with better nutritional value.

If you don’t believe me, google what bananas naturally look like. They’re not very appetizing!

That said, meat played a fascinating role in jump-starting human culture. Or, at least it used to. Now we have reason to believe slaughtering livestock at our current consumption levels may ultimately slaughter ourselves.

But — let’s start with the story of how you and I became human.

Through most of the six million years after we split from chimpanzees, we roamed our African homeland with other australopithecines — ape-like creatures with human features who walked upright. We were, for the most part, vegetarian. We probably ate a little meat, but only when the opportunity presented itself; nothing like the amount today.

This shouldn’t come as too much of a surprise. Considering the amount of work required to turn a living animal with a full set of survival instincts into our dinner, we opted for easier prey: nuts, berries, and all things foraging.

Biologist and naturalist Edward O. Wilson observes that animals “relying on coarser, more fibrous plants evolved heavier jaws and teeth.” These specializations represent what evolutionary biologists call an adaptive radiation.

At some point, one of our old lineages shifted to heavier meat consumption, especially meat cooked by lightning-struck grassland and savanna ground-fires. Our ancestors didn’t start the fires (queue Billy Joel), but they sure took advantage of them — stopping to rest around the cooked carcass, and eating it before others could steal its precious meat.

It wasn’t long before they realized they didn’t need to carry burning branches from one flaming location to another; they could start it on their own. They could control fire.

Not only did firelight allow us to work for longer hours after the sun went down and keep predators at bay, but it also allowed us to benefit from a heavier meat-based diet.

“It was evidently in Homo habilis, present in Africa between 2.3 and 1.5 million years ago, that the swerve began that ended in modern humanity,” Wilson says. “In its segment of prehistory, the cranial capacity, hence brain size, rose from 500 to 800 cc, well above the size of the modern chimpanzee.”

It grew again and again, first to the size of Homo erectus (about 1,000 ccs), then to 1,300 cc or more — enter modern man.

So what does all this have to do with meat?

“Those relying on coarser, more fibrous plants evolved heavier jaws and teeth.”
—Edward O. Wilson, biologist and naturalist.

Heavy jaws and teeth must be powered by big muscles. As our ancestors ate more and more meat, they needed less and less powerful jaws to break down fibrous plants because fibrous plants no longer made up as much of their diet.

Their jaw muscles atrophied, and gradually, their skulls made more room for brain matter and less room for chewing muscles. And by the time of Homo erectus, our ancestors not only had larger brains but smaller and lighter jaws and teeth too.

Fast forward to Homo sapiens today and you’ll find we have huge brains and very weak jaws relative to almost every species on the planet, including our primate relatives.

Adding meat to our diet made our brains grow, and the protein helped our bodies develop too. It’s not like they had soybeans and chickpeas back then!

Wilson says these larger brains gave us larger memories, leading to the construction of internal storytelling. And then, for the first time in the history of life, to true language. “From language came our unprecedented creativity and culture,” he finishes. And it all started with meat.

This may seem like a bit of a leap. Surely, meat couldn’t have been that influential? It was. In fact, it might have been exponential.

The sudden burst of human language and culture out of millions of years of nothing is remarkably similar to the sudden burst of technology from the 1950s to now. And think about what changed.

The first thing that probably comes to mind is that technology got smaller. Computers used to take up entire buildings; now they fit in your pocket. But what changed wasn’t the size. It was size related to memory capacity.

We could all be walking around with smartphones that do little more than solve simple math problems, but that’s clearly not the case. Rather, we found a way to cram a lot of storage into a very small space.

That’s precisely what eating more meat did for our ancestors. And it was exponential because each person would share the contents of their squishy grey matter storage unit with everyone else in their community, who were also developing upgraded squishy storage units.

Sharing knowledge and retaining it is critical for the evolution of an intelligent species. We see this when we look at another intelligent creature that’s existed for millions of years before anything even close to resembling a human came on the scene. I’m talking about the octopus.

Octopuses are smart. They use broken coconut shells as mobile armour, squirt water at indoor lights to short-circuit the power supply, solve simple mazes, open screw-top jars without ever having encountered one before, and plug their tanks’ outflow valves, causing overflow and a chance to escape.

They also have about as many neurons as dogs and a large brain relative to the size of their body. So why aren’t they as intelligent as humans or dolphins?

Scientists such as Peter Godfrey-Smith, now a professor at Harvard, believe this is because, despite their impressive creative problem-solving abilities, octopuses live short solitary lives. They’re smart, but they don’t share their smarts with other octopuses and they don’t live in communities where they could benefit from other smart octopuses teaching them in return.

You can read more about Octopus intelligence in Peter Godfrey-Smith’s book: Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness

Humans are different. Humans are social. And it was human sociability, combined with a desire to eat more meat, that forced our ancestors into closer quarters with each other and for longer periods of time.

Without meat, they hunkered down wherever they could find shelter, snacking on food that didn’t need to be cooked. Now they could use fire to ward off predators, allowing for greater life expectancy to share and learn new knowledge, and with that protection and visibility, they could tell stories, form social bonds, and pass on the wisdom of the ages.

So doesn’t this mean that fire made us human? Yes, and no.

You can’t eat fire and therefore fire alone had nothing to do with our jaws and teeth becoming softer and weaker. It was eating meat that did this, and in turn allowed our cranial size and, by extension, brain size to grow larger and smarter.

Where does this leave us today? Just because meat made us human doesn’t mean it’s healthy for us at the level we currently consume it or for our continued survival as a species.

Too much red meat can cause heart disease, calcium-loss leading to bad bone health, and long term weight gain — among other nasty conditions. The result isn’t pretty. A meat-heavy diet can leave the body carrying a heavy load on a weak skeleton with a defective motor desperately pumping to keep everything running smoothly. Listen, I love a juicy red steak as much as the next guy, and you can bet I’ll mop up the extra blood with garlic bread too, but that doesn’t mean I’ll sacrifice the one body I have for more meat.

It’s perfectly possible to love meat while still accepting the fact that it isn’t always healthy. Admitting this won’t turn you into a radical vegan, I promise.

In addition to the health effects of eating too much meat, there are also environmental costs. The red meat industry is one of the biggest sources of pollution in the world. That may sound absurd on the surface, but let’s break it down.

There are 1.4 billion cattle in the world. With 7.53 billion people in the world right now, that’s enough cattle for every 5 people to own a cow. Seriously.

Each cow shoots out anywhere from 70–120kg of methane. And each of those puffs added together has a huge effect on climate because methane is a potent greenhouse gas. In fact, according to Alejandra Borunda of the National Geographic, methane is “28 times more powerful than carbon dioxide at warming the Earth, on a 100-year timescale, and more than 80 times more powerful over 20 years.”

This environmental issue exists on an even broader scale, and with even greater implications.

Let’s not forget raising more cattle means clearing more land, and cattle don’t live in forests. Trees must be chopped down. We’re seeing the devastating effects of what this means right now as Brazilian farmers continue to burn the Amazon. And every acre cleared is that many fewer trees to absorb pollutants all while adding more methane gas to an already overwhelmed planet.

Let me be clear: I love meat. It tastes great and, in moderation, it’s good for us. It helped make us human. But the amount we eat today is nowhere near the amount we used to eat.

Like a herd that overgrazes and is forced to confront starvation later, we’re eating up the land in order to eat more meat later — and sabotaging ourselves in the process.

I’m not going to shame you for eating meat and I disagree with people that do. We evolved as omnivores. We still are. That means eating a wide variety of food, including meat. But I also know you don’t have to transform into a militant vegan to do what’s good for both your body and the planet.

I’ve cut down on the red meat in my diet, substituting it with poultry and fish — and, honestly, I feel much better. Not just because I’m taking care of the environment, although that makes me feel good too, but more because fish is rich in Omega-3s, which helps me burn fat and stay in shape, and chicken provides lean protein that helps me build my muscles and look good and feel confident.

My point is I’m not cutting back on red meat for entirely selfless reasons, and you don’t have to either.

Meat helped make us human, but it also gave us the brain capacity to reflect on ourselves and the world we live in, to build beautiful languages and communities, and to make adjustments to improve the quality of life for everyone. More than meat, more than fire, our dynamic ability to analyse problems and come up with solutions is what makes us human today.

Let’s not squander that.