Book Summaries health

A Return to the Past (The Story of the Human Body)

Some have called for a return to the Paleolithic lifestyle, since it is healthier than our modern world, where people lounge in chairs all day long and eat domesticated plants and animals, and drink coffee.

But the short answer is that there is no ideal environment for the human body. For example, short legs helped humans conserve heat in cold climates but is disadvantageous to running or walking long distances efficiently. Natural selection rarely achieves perfection because no environment is the same.

An individual’s adaptations are the imperfect product of a series of constantly changing compromises. Natural selection pushes organisms towards optimality, but optimality is impossible to achieve

Finally, no organism is adapted to be healthy, happy, or long lived, or to achieve any other goal that humans set for themselves. Adaptations evolve to promote these things only if they benefit an individual’s ability to have more surviving offspring. Humans evolved to be prone to obesity not because it makes us healthy, but makes it increases fertility.

We are not adapted for a single diet, social environment, or exercise regime.


We don’t really know how much meat we used to eat. Hunter-gatherers must have craved meat then as humans and chimps do today. And for good reason. Eating an antelope steak yields five times more energy than an equal mass of carrots, as well as essential proteins and fats. Meat is a rich food source and has been an important component of the human diet ever since early Homo. But being a part-time carnivore is time consuming and challenging. We an infer that division of labor made it possible for males to gather and hunt while females mostly gathered.

A hallmark to this division of labor is food sharing. Male chimps rarely share food and don’t share food with their offspring. But Huntergatherers marry each other, and husbands invest heavily in their wives and offspring by providing them with food. By sharing meat when the hunts are successful, a hunter increases his chances of getting meat when he goes home empty-handed. Today, greed and selfishness are sins, but in the world of hunter-gatherers, they could mean the difference between life and death.


Chimps can’t grip pencils or other tools, but humans can, because we have long thumbs and short fingers, as well as very strong thumb muscles and robust finger bones.

One of the most important inventions was fire. Cooking was a transformative advance. Cooked food yields more energy than uncooked food and is less likely to make you sick, Fire allowed archaic humans to stay warm in cold weather and to fend off dangerous predators like cave bears. Fire also helped humans stay up at night.


The Neanderthals were successful hunter-gatherers who would probably still exist had it not been for H. sapiens. The Neanderthals made sophisticated stone tools that they fashioned into a wide variety of tool types such as scrapers and points. They cooked their food and hunted big animals. But the Neanderthals, despite their
accomplishments, were not completely modern in their behavior. They buried their dead simply, and left no traces of symbolic behavior such as art. But they had big brains and were considered very intelligent.

The Gift of Gab

A creative idea or valuable fact is useless if you can’t communicate it. Thanks to technologies that have advanced the spread of information, such as writing, the printing press, the telephone, and the internet, we have made fundamental leaps in communication. Even though Neanderthals had language, the uniquely short and retracted face of modern humans would have made us better at making clear, easy-to-interpret speech sounds at very quickly. We are a silver-tongued species.

Life’s Simple Pleasures

Humans have brought many calamities to themselves by modifying their environment. But there is a lot of good to be said about culture.

Capitalism has made it possible for nearly anyone to enjoy opportunities that even the richest aristocrats could not have imagined centuries ago. Few have a serious desire to live permanently in the woods or as a caveman without health care, education, sanitation, variety, meaningful work, hot showers, and air-conditioning.

But it would be foolish to ignore the many challenges that humans now confront. Farming, industrialization, and other forms of “progress” may have been a blessing to the average person, but they promoted diseases and other problems that were rare or absent during the Paleolithic.

Every major infectious epidemic, such as smallpox, polio, and the plague, happened after the Agricultural Revolution began. And while hunter-gatherers did not enjoy a food surplus, they rarely suffered from famines or serious malnutrition.

Modern lifestyles have fostered non-infectious but common illnesses like heart disease, certain cancers, osteoporosis, type 2 diabetes, and Alzheimer’s, as well as scores of other lesser ailments, such as cavities and chronic constipation. There is good reason to believe that modern environments is a leading cause of many mental illnesses, such as anxiety and depression.

"Silence is the best expression of scorn" - G.B. Shaw

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