Carrying Kids: The Incredible Science and Benefits, Part II

The science of carrying kids reveals that carrying lighter weights is the most essential fitness hack you’re not doing.

Why it matters: This information will make your workouts smarter, not harder; prevent and relieve back pain; and much more.

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On Monday, we covered how humans evolved to carry our kids and all the benefits of kid-carrying.

Today we’re covering:

• How rucking evolved from carrying kids (this is crazy fascinating).
• How to apply lessons from the evolution of child carrying to improve your health and fitness (even if you don’t have kids).
• An epic carrying challenge.

Let’s roll …

How rucking evolved from carrying kids

As I described it in The Comfort Crisis:

“Ruck” is both a noun and a verb. It’s a thing and an action. It’s military-speak for the heavy backpack that carries all of the items a soldier needs to fight a war. And “to ruck” or “rucking” is the act of marching that ruck in war, or as a form of training for soldiers or civilians to get really, really fit.

But the rucksack and rucking didn’t start with warfare.

A team of scientists from five universities worldwide studied the act of child carrying. The scientists wrote:

In all cultures across time, daily tasks must be done whilst caring for infants. The ability to nurture infants while working likely gave rise to the use of traditional cloth and basket.

It happened like this:

• Two million years ago, mothers looking to carry their kids more efficiently invented the first “carrying tools” by weaving together baskets and sashes.
• They then put their baby inside those baskets, keeping the baby close and safe while freeing up the mother’s hands so she could gather food and do all sorts of other tasks.

These carriers “would have enhanced infant safety and mothers’ efficiency while foraging,” the scientists wrote.

The importance of this invention can’t be understated. When these mothers created baby carriers, half the population basically doubled their productivity. These devices also protected the baby, increasing the human survival rate.

To understand what these carriers were like, the scientists pointed to various baby carriers in different cultures.

• Tribes in the Amazon like the Awa, Yequana, Yanomami, and Kayapo used tree fiber sashes to carry the baby on a hip or back.
• The Jarawa people in India used a similar sash wrapped around their heads to carry the baby against their backs.
• Tribes in Cameroon, Tanzania, and Greenland used the skins from antelope, goat, and seal, respectively, to carry infants across their backs.

And on and on.

But the invention of the baby carriers didn’t stick with babies.

Humans then made the leap of, “well, if we can carry babies in this tool, we can also use it to carry all sorts of other stuff.” Food, resources, other tools to explore the unknown. Humanity exploded from there.

It was a “one small step for women, one giant leap for humankind” moment.

But when humans began living in much safer environments, we could put our kids down for longer stretches of time. Then strollers and other off-body devices led us to carry our kids less.

Living in a safer, more efficient world is excellent. But we lost some upsides of kid carrying.

So what should we do?

Carry kids enough

Scientists believe you can’t hold your infant too much—but you can hold it too little. And when you don’t hold a baby enough, the child suffers. It impacts their physical, social, cognitive, and emotional development.

But the scientists don’t know exactly what the ideal dose of holding is. Clearly you can’t hold a baby every waking hour. There’s likely some point of “enough” that varies from kid to kid. So the most reasonable thing to do is to hold infants as frequently as feels reasonable. Like, if you’re watching TV, hold the kid instead of lying it in a bassinet on the floor.

Carry weights more often

Carrying light weights frequently in different positions is particularly good for our physical health.

We changed when we we began carrying less often.

Think about it: Humans evolved as the ultimate carriers. We’re physically engineered for it. And we do it far less often today.

Carrying light loads for a long time has two major upsides:

It’s a killer form of cardio

The health and fitness world is obsessed with “Zone 2 Cardio.” It’s really just a fancy way of saying “do physical activities that feel like exercise but aren’t too hard.”

This easy exercise does many good things for your health, metabolism, endurance, and recovery.

My advice is to not overthink cardio zones and heart rates and all that. Just move around frequently in a way that gets your heart rate up but still allows you to have a conversation.

Enter carrying: Carrying light loads is a fantastic way to do this. It’s harder than walking, putting you in the sweet spot.

It’s practical strength work (that can save you a lot of pain)

When carrying weight, you’re covering ground as most of your muscle groups work harder: Your arms, shoulders, core, legs, etc.

This mixes strength and cardio. And that seems to be uniquely good at stimulating fat loss.

But it also has another big benefit.

When reporting The Comfort Crisis, I learned 80 percent of Americans will suffer from back pain. And it can be debilitating. When people start having a “bad back,” they move less. And that begins a slide into all sorts of health problems.

And over 90 percent of this back pain is “non-specific.” This type of pain tends to arise from a weak back that suddenly gets tested, like while bending over to pick up a heavy item. The muscles can’t handle it, and the stress goes to your spine.

Our backs are weaker for two key reasons:

1. We sit in comfortable chairs more
   When we sit, we no longer sit in a way where we have to use our muscles to keep our torso upright. We can sink into soft chairs and effectively shut off our muscles.
2. We carry less often
   Carrying weight—especially lighter weights for longer durations, not super heavy weights for shorter durations—seems to be uniquely good for our backs. Your back muscles must fire on in different ways to stabilize the load. That makes your back more resilient. Translation: Less risk of injury and pain.

Smart new ways to carry weight

So how do we take these lessons and apply them to our health?

There’s rucking, where we walk with a weighted pack on our back. That’s the most practical way to get in the door.

But if you look at the evolution of how we carried children, there’s a solid argument to change up how we carry weight. Here’s what you should do to unlock the benefits: