Book Review: Mean Genes

1: Money Won’t Accumulate, but Fat Sure Does#

For example, “spending too much money and never saving anything” and “eating too much food and accumulating fat” are two sides of the very same coin when viewed through the lens of Mean Genes.

Long ago, for humans and other animals living in an age before refrigerators, food—their wealth—would rot in a matter of days. When you came into great wealth, the best option was to consume it immediately and store the energy in the form of fat.

Having ancestors who survived precisely because this strategy was successful, it’s perhaps inevitable that we can’t stop consuming and can’t save money. After all, we carry genes programmed with this strategy.

This explanation is convincing. But the great thing about this book is that it doesn’t just trace the cause of foolish behavior to genetics—it also introduces ways to hack our instincts using the power of reason.

We consume because the wealth is there. If you truly want to save, you should quickly move that wealth somewhere out of sight or out of reach. For example, you could intentionally put your savings in an inconvenient bank, or have investment funds automatically deducted from your salary before being deposited.

If you want to avoid overeating, you can either fill your stomach before you’re swayed by desire, or make sure food is out of reach. Before going shopping at the supermarket, fill your stomach with low-calorie food beforehand. If you already have food on hand, you can preemptively throw it away. One of the authors reportedly slathers mayonnaise all over the brownie that comes with his in-flight meal. That way, his stomach turns and he can’t possibly bring himself to eat it (though this probably wouldn’t work for mayo addicts).

2: Infidelity Is Rational for Genes#

In modern married couples, divorce is often caused by one partner’s infidelity. Unfortunately, from the perspective of genes, there is a certain rationality to cheating.

Marriage is, in short, a kind of contract. The woman promises the man, “I will bear your child,” and the man promises the woman, “I will invest in the child that is born.” When the temporary but immense cost the woman pays at childbirth balances with the prospect of the man’s long-term investment costs, the two marry and have a child.

So if an opportunity presents itself to break the promise and enjoy only the benefits, it’s no surprise that people are drawn to it.

For a man, scattering his genes without investing (in other words, irresponsible creampies) is a thoroughly rational move. Meanwhile, for a woman, keeping her current partner on the hook as a sucker while getting fertilized by genes with superior genetic traits (in other words, brood parasitism / cuckoldry) is also a rational move.

Reactions to such breaches of contract also seem to differ between men and women. Men feel intense revulsion when a trusted partner sleeps with another man. Women feel intense revulsion when a trusted partner forms a deep emotional connection with another woman.

If you don’t want to taste betrayal, the essential first step is to earn your partner’s trust. The higher the risk of being betrayed, the stronger the incentive to launch a preemptive strike. Keeping promises and expressing affection on a daily basis become that much more important.

Alternatively, aiming to become someone who possesses more of the desirable traits that should be passed on to future children is another option. There are many factors you can improve through your own efforts, such as health, personality, and social status. The key is to show that a child carrying your genes is an excellent investment (in other words, having a high survival rate and a strong probability of leaving behind many grandchildren).

3: The World Isn’t as Small as Our Genes Think#

Examining archaeological remains from the hunter-gatherer era reveals that humans apparently lived in groups of at most a few hundred people. And almost everyone spent their entire lives within that same group.

Under such an environment, being looked down upon or disliked by others was literally fatal. That is why, for example, when someone cuts us off on the highway, we get irritated and sometimes even retaliate. When we fight with an acquaintance, we feel deeply down. Or we become excessively afraid of failing at work, and get completely engrossed in gossip columns.

Yet in modern society, an incomparably greater number of people live around us. What’s more, moving between groups is far easier. Even if someone cuts you off, the actual damage incurred is merely arriving a few seconds later at your destination. There is no chance they will boast to everyone, “That guy’s a soft touch who just stays quiet when you cut him off!”

Likewise, gathering gossip from all over the world regardless of distance may have been rational when groups were small. But obsessing over the gossip of celebrities or fictional characters you will likely never meet in your life is completely meaningless. Recall the birds deceived by the giant fake eggs mentioned at the beginning. They are nothing more than junk food information that tickles our instincts, of virtually no use to our actual lives.

In modern times, the risk of interpersonal conflict is far smaller than our instincts warn us. Losing a little status or honor within a group rarely leads to death, and changing the group you belong to is always an option in the first place. That is why, especially in relationships and work, we should push past our instinctual tolerance and embrace risk more actively.