The Rise and Reign of the Mammals: A New History, From the Shadow of the Dinosaurs to US, Steve Brusatte, c. 2022.

Before we get started, the difference between "hominid" and "hominin." Link here.

From my Winter Reading Program, 2022 - 2023.

I've read it once, and have read and re-read several sections several times.

Today what caught my attention: how fast hominins / Homo evolved / developed once the process began.

The age of the earth, 4+ billion years old.

Mammals and dinosaurs lived side-by-side at the height of the dinosaur eras. 

The "marker" is 66 mya when the asteroid which led to the demise of non-avian dinosaurs and the rise of mammals.

Sixty-six million years ago when evolution is measured in billions of years.

Mammals, dinosaurs, reptiles co-existed 100 million years ago. Again, evolution measured in billions of years and mammals, dinosaurs, reptiles co-existed 100 million years ago. 

Primates -- off the mammalian line -- show up 85 million years ago. 

Twenty million years go by: primates, mammals, reptiles, dinosaurs happy as larks.

Then, out of thin air, 66 million years ago, the asteroid.

Primates continue to evolve over the next sixty million years.

So, from talking about evolution over billions of years, we are now compressing primate evolution in under 100 million. 

Sixty-six million years ago, small, burrowing primates start moving into niches left void by the disappearing dinosaurs.

Around six million years ago, the primates as we know them start the long split: the great apes separate from the smaller apes. The Miocene: the planet of the apes. The great apes split into gorillas in Africa, orangutans in Asia. The last common ancestor of the two is yet to evolve / split into chimps and hominins.

Or it's possible the LCA of the great apes included the chimps. I need to sort that out.

Regardless, the hominins appear 5 - 7 million years ago.

So, in evolution dating, we've gone from billions of years to 300 million years to 66 millions to 6 million years.

For me, it is simply amazing how fast things progressed after the asteroid hit 66 million years ago.

But after 6 million years ago, things -- at least for hominins / Homos really sped up.

Six million years ago "we're" still part of the great ape - chimp family.

Six million years ago: "we" still looked a lot like chimps.

The first hominin: Ardipithecus ramidus. A walker / climber.

Then, the most famous hominin: "Lucy," Australopithecus. A walker. 3.6 million years ago.

A million years is a long time when humans measure civilization in millenia (thousands of years) but, still, two million years from looking like chimps to looking like humans is really, really fast.  

But then look at this, 3.6 million years ago to 2.8 million years ago -- less than a million years ago, and a new genus is born: Homo. 

Homo erectus.  

The likely catalyst: somewhere between "Lucy" and Homo erectus, a hominin started eating meat.

300,000 years ago, the first Homo sapiens shows up. Us. Homo sapiens. 300,000 years go; shows up first in Morocco.

 Between 100,000 and 40,000 years ago, there are multiple subspecies of Homo sapiens.

How recent is 40,000 years ago.

Helen of Troy: 12,000 years ago.

That blows me away.

Not too long ago, we're "measuring" evolution in hundreds and then tens of millions of years when "we" still looked like chimps, and all of a sudden, 40,000 years ago "we've" reached modernity.

Twenty to thirty thousand years later, a snap of the fingers and Greeks are floating 1,000-ship armadas to attack the Trojans.