I reviewed four new science books for The New York Times. They span millions of years, beginning with the birth of humanity and ending with a serious look at AI. 

Since 2004, I’ve spent a lot of time staring at the ceiling thinking about tsunamis and earthquakes. The monster wave that hit Indonesia that year was caused by a earthquake so violent it shifted the axis of the earth a few centimeters. Now I can’t get this out of my mind: The planet literally shook.

Everyone has one--whether its global warming, phthalates, flu, or junk food--it's that thought that makes them quake. Still, despite the fear, most people do their best to live sustainably, heal naturally, and raise their children right.

But how often is it that one's efforts feel good enough? For the most part, the solutions are inadequate or unachievable or overwhelmingly, confusingly both. If you turn on the air conditioner because you are too warm, you cause global warming. If you vaccinate your children to protect them, you fear the vaccine may hurt them, and yet if you get cancer, it’s your fault for being so angry and fearful all the time. What if you don’t actually want to walk to the local abattoir and slaughter your own pig so you can eat your sausages morally? What does that even mean?

You could consider optimism, for a change. I thought about it a lot when I reviewed Matt Ridley's "The Rational Optimist."

I Cook, Therefore I Am. How dropping food in fire made us human. Slate

WHY is it that 20th-century physicists could ask some of the most grandiose questions in science, but if a researcher wondered aloud where language came from, the response was derisive at best. Not only can you not answer the question, they were told, you shouldn't even ask... New Scientist

Songs that travel for thousand of miles. Songs that replicate over thousands of years.

Modern humans originated in Sub-saharan Africa, and from there spread all over the globe. Cambridge scientists, who published their study today in Nature, used genetic information combined with the measurements of 6000 skulls from collections all over the world in order to confirm what's known as the 'Out of Africa' theory. The idea of African origins for humans has become very widely accepted over the last ten or so years--this new study deals a final blow to scholars hanging onto the notion that humans may have originated in separate locations all over the world. SciAM.

In this week's PNAS, scientists have compared how much energy is used in human bipedal walking compared to the four-legged gait of chimpanzees (and even bipedal walking in chimpanzees). In general, they found that energy is saved with longer steps and less active muscle mass, and in fact that humans use about 75% less energy getting around than apes do. The difference is huge. It is said that natural selection generally proceeds by very small advantages but if the first human to start walking more upright was able to conserve even a percentage of this, it must have given them a great opportunity to spend that energy elsewhere (Feeding a large brain? Using language?).  USA Today, NatGeo.

Shell beads that were once strung together and covered in red ochre have been found in Grotte des Pigeons, Morocco. The beads date to 82,000 years ago, five thousand years older than similar artifacts found in South Africa's Blombos Caves (previously thought to be the oldest human artifacts). Together they suggest that bead-making was not an isolated, rare activity but was spread amongst different human groups at this time. NatGeo, PNAS.