Dan Flores

Clearly, we ancient hunters of animals surrendered our oldest life away with reluctance. America wasn't just in the throes of biological recreation. Around 8,500 years ago, there was another potent change. The warming cycle that ended the last ice age didn't relent, and America's climate swung into a hot, dry phase that stayed in place for a mind-blowing 3,700 years.

Clearly, we ancient hunters of animals surrendered our oldest life away with reluctance. America wasn't just in the throes of biological recreation. Around 8,500 years ago, there was another potent change. The warming cycle that ended the last ice age didn't relent, and America's climate swung into a hot, dry phase that stayed in place for a mind-blowing 3,700 years.

This was the depths of the last interglacial, the long slide out of the frozen Wisconsin Ice Age. Now the Earth's rotational wobble had the northern hemisphere slightly closer to the sun, and for almost 40 centuries, some parts of America cooked. The Altothermal, as it's called, came close to turning large parts of the continent into a true desert and a vacant one.

This was the depths of the last interglacial, the long slide out of the frozen Wisconsin Ice Age. Now the Earth's rotational wobble had the northern hemisphere slightly closer to the sun, and for almost 40 centuries, some parts of America cooked. The Altothermal, as it's called, came close to turning large parts of the continent into a true desert and a vacant one.

This was the depths of the last interglacial, the long slide out of the frozen Wisconsin Ice Age. Now the Earth's rotational wobble had the northern hemisphere slightly closer to the sun, and for almost 40 centuries, some parts of America cooked. The Altothermal, as it's called, came close to turning large parts of the continent into a true desert and a vacant one.

Many species of animals left for wetter settings. So did many human groups, like other animals shifting eastward and westward out of the interior west. The country where Clovis and Folsom people thrived nearly emptied of humans during the Altothermal. But once the altothermal subsided, generations of hunter-gatherer peoples returned to occupy the same landscapes for centuries.

Many species of animals left for wetter settings. So did many human groups, like other animals shifting eastward and westward out of the interior west. The country where Clovis and Folsom people thrived nearly emptied of humans during the Altothermal. But once the altothermal subsided, generations of hunter-gatherer peoples returned to occupy the same landscapes for centuries.

Many species of animals left for wetter settings. So did many human groups, like other animals shifting eastward and westward out of the interior west. The country where Clovis and Folsom people thrived nearly emptied of humans during the Altothermal. But once the altothermal subsided, generations of hunter-gatherer peoples returned to occupy the same landscapes for centuries.

That kind of close familiarity gave them bodies of handed-down ecological insights about how to live in particular places. The feedbacks they read from place-based living enable humans to come up with a striking epiphany, one allowing them to live well without using up their world.

That kind of close familiarity gave them bodies of handed-down ecological insights about how to live in particular places. The feedbacks they read from place-based living enable humans to come up with a striking epiphany, one allowing them to live well without using up their world.

That kind of close familiarity gave them bodies of handed-down ecological insights about how to live in particular places. The feedbacks they read from place-based living enable humans to come up with a striking epiphany, one allowing them to live well without using up their world.

The breakthrough, a key to success in Native America, sprang from the realization that there was no longer a wild new world empty of other people out there. Clovis-like expansion across a virtually uninhabited continent was over. Humans now had to learn to deliberately, carefully manage their own numbers to avoid overshooting local resources when times turned bad.

The breakthrough, a key to success in Native America, sprang from the realization that there was no longer a wild new world empty of other people out there. Clovis-like expansion across a virtually uninhabited continent was over. Humans now had to learn to deliberately, carefully manage their own numbers to avoid overshooting local resources when times turned bad.

The breakthrough, a key to success in Native America, sprang from the realization that there was no longer a wild new world empty of other people out there. Clovis-like expansion across a virtually uninhabited continent was over. Humans now had to learn to deliberately, carefully manage their own numbers to avoid overshooting local resources when times turned bad.

In a variable world, good times inevitably give way to bad times. That was an ancient lesson. Basing your numbers on the good times could set you up for disaster. How did these ancient Americans manage to pull off controlling their populations so they could live well on local resources? Birth spacing was one common strategy.

In a variable world, good times inevitably give way to bad times. That was an ancient lesson. Basing your numbers on the good times could set you up for disaster. How did these ancient Americans manage to pull off controlling their populations so they could live well on local resources? Birth spacing was one common strategy.

In a variable world, good times inevitably give way to bad times. That was an ancient lesson. Basing your numbers on the good times could set you up for disaster. How did these ancient Americans manage to pull off controlling their populations so they could live well on local resources? Birth spacing was one common strategy.

Breastfeeding suppresses ovulation during a mother's fertile years, preventing a rapid succession of pregnancies. Child mortality was high among ancient humans anyway. But most hunter-gatherers practiced forms of abortion to control their populations, and the evidence is that as an ecological strategy, it worked well.

Breastfeeding suppresses ovulation during a mother's fertile years, preventing a rapid succession of pregnancies. Child mortality was high among ancient humans anyway. But most hunter-gatherers practiced forms of abortion to control their populations, and the evidence is that as an ecological strategy, it worked well.

Breastfeeding suppresses ovulation during a mother's fertile years, preventing a rapid succession of pregnancies. Child mortality was high among ancient humans anyway. But most hunter-gatherers practiced forms of abortion to control their populations, and the evidence is that as an ecological strategy, it worked well.