plants’ fight for survival, chemicals are their weapons of choice. (They are particularly good at poisoning animals.) That’s why they make so many of our drugs, such as salicin, a relative of aspirin (found in the bark of willow trees), the cancer fighter Taxol (in yew trees), and the malaria drug quinine (in the Andean cinchona tree). To mess with

Many genes are controlled by other genes located far away, which, in turn, are switched on or off by others elsewhere. One gene may activate a suite of genes, each of which turns on others in a cascade, like a computer program activating subroutines. How, then, do we grow in the womb from a single-cell embryo to a creature with arms, legs, a heart,

In the nineteenth century, the Austrian monk Gregor Mendel had shown that you could trace the transmission of a trait in plants, like height or seed shape, from one generation to the next. Scientists named whatever it was in a cell that transmitted a trait a gene, from the Greek word genos, “birth” or “clan.”

Prout was also the first to propose that our food contains three essential substances, which he called “the saccharine, the oily, and the albuminous.” We know them as carbohydrates, fats, and proteins. As proof, Prout observed that all three are found in a mother’s milk. If we did not need them, it was evident to Prout, God would not have put them

Scientists discovered that our nerves also use these pumps for something else. They send electrical messages, but not with electrons or protons. Researchers began learning how this works in 1939 when they found that, for defense, armorless giant squid rely mainly on fast escapes made possible by giant neurons. These nerves were so wide, investigato

When Watson showed the physicist Leo Szilard the model, Szilard immediately asked him, “Can you patent it?”50 (Szilard himself had many patents, including one on the nuclear chain reaction, which he donated to the British government in 1934.) But Watson knew you can’t patent anything without a practical application, and he still had no idea how gen

Mitchell proposed—and this was weird—that a mitochondrion used its membrane to create an electric current that powers the cell. It made this current not from negatively charged electrons, like the ones flowing through our electric wires and appliances, but from positively charged protons—hydrogen nuclei. And it used the current to power a mechanism

A typical cell within you is made of a galaxy of atoms—a hundred trillion or so of them. A stack of that many dollar bills would reach to the Moon and back over twenty-five times. Every second within each of your cells, many hundreds of millions of molecules are shooting in and out of membranes. Thousands of genes are being locked and unlocked. Mil

Once photosynthesis entered the picture, life on Earth was no longer solely dependent on whatever chemical energy it could scrounge up on the Earth’s surface. Life could draw vastly more energy from the fusion of hydrogen into helium, over 90 million miles away in the Sun. All the energy we expend during our existence was emitted as light from our