The Great Depression of the 1930s saw more American unmarried women working from nine to five, mostly in repetitive, boring, subordinate, dead-end jobs. But the number of working women doubled between 1870 and 1940. During World War II it doubled once again.

Natural beauty really entices men. They will tell you this time and time again, and studies consistently prove it.

Today, most women are surrounded by ingenious gadgets. They don't grow the peas or raise the chicken that they serve for dinner; instead they hunt and gather in the grocery store. They go through catalogs or department stores to buy clothes instead of shearing sheep, carding wool, and weaving cloth for skirts and coats and blankets.

I think you will find that with divorce will come happier remarriages.

Nobody gets out of love alive. You turn into a menace or a pest when you've been rejected.

There's biology in everything, even when you're feeling spiritual.

As social animals, we need to exchange juicy tales about someone - to connect with one another. For millions of years our forebears must have sat around the campfire, whispering about everyone they knew.

For so many generations, a woman's only career path was to marry well and to marry up. Those days have changed.

Any kind of novelty or excitement drives up dopamine in the brain, and dopamine is associated with romantic love.

Why do we feel jealousy? Therapists often regard the demon as a scar of childhood trauma or a symptom of a psychological problem. And it's true that people who feel inadequate, insecure, or overly dependent tend to be more jealous than others.

There's a lot of talk about the positive aspects of love. We as a society downplay the danger, the anxiety, and the disappointment. We romanticize romance.

Real competition can drive up testosterone, which boosts libido.

A hundred years ago, if you had a child out of marriage, you'd be a social disgrace. Today women feel comfortable enough economically and culturally to bring up a child without a recognized commitment from a man.

Kissing is not just kissing. It is a major escalation or de-escalation point in a powerful process of mate choice.

I have always been interested in how you can walk into a room and there will be 40 people there and you are immediately drawn to one.

People kill for love. They die for love.

Until recently, we regarded love as supernatural. We were willing to study the brain chemistry of fear and depression and anger but not love.

Romantic love is an addiction.

Anthropologists have found evidence of romantic love in 170 societies. They've never found a society that did not have it.

I think that property is very important in this day and age. It defines you; you worked hard to get it. It's meaningful to you, and when you divorce, a lot of people have a lot of battles over their property for good reasons.

Good-looking people are always looking for other good-looking people.

Men and women are like two feet; they can help each other get ahead.

Globalization requires taking a broad contextual and long-term view.

Women have a better sense of color and a better color memory. They're more likely to notice when something doesn't match; more likely to notice what you're wearing.

When you massage someone, the levels of oxytocin go up in the brain, and oxytocin is one of the chemicals that drives attachment.

Research shows that couples who have a lot of similarities, including intellectual compatibility, end up staying together.

At first I assumed hate was the opposite of love. But it isn't. The opposite of love is indifference.

Mothers really were not built to raise babies not only by themselves, but with only a partner. For millions of years, a woman had much more than just her husband to help rear her young... This whole idea of 'it takes a village to raise a child' is exactly how we're supposed to live.

There is more and more data indicating that there is a biological basis to your political views.

When chimps threaten, they open their mouth and show their teeth. It's a little like waving a knife in front of you. It's very primitive, and therefore bizarre.

When you look at the brain regions associated with picking up data from the body, a huge amount of the brain is devoted to picking up information from the lips and tongue.

You know, when you've been dumped, the one thing you love to do is just forget about this human being, and then go on with your life - but no, you just love them harder.

The human brain is built to compare; it's Darwinian to consider an alternative when one presents itself.

Saliva has testosterone and estrogen. When you kiss, you're having a chemical experience.

It certainly would have been adaptive for ancestral man to have a chubby wife during stressful times of famine. Not only would she have had more calories to burn, and thus more energy and endurance, but since fat stores estrogen, she would have remained fertile for longer.

Hair that gleams can send a clear sign that you're young and in your prime, whatever your actual age.

You've got to remember that men are men and women are women. And although a lot of similarities, there are some real differences.

Both sexes like the exercise and challenge of sports, but for men it's also a basic display behavior for impressing and winning a mate.

Hair that looks like it's been naturally sun-bleached makes you seem youthful, like you spend a lot of time outdoors. And that appeals to most people.

Your sweetheart calls you by another's name. His eyes linger too long on your best friend. He talks with excitement about a girl at work. And the fire catches. Jealousy - that sickening combination of possessiveness, suspicion, rage, and humiliation - can overtake your mind and threaten your very core as you contemplate your rival.

Young women today do not marry the men they met in high school, or even the one they go out with at college, because they do not need to.

Jealousy can even be good for love. One partner may feel secretly flattered when the other is mildly jealous. And catching someone flirting with your beloved can spark the kind of lust and romance that reignites a relationship.

Overdone lipstick is a deterrent to men. It rubs off easily onto their skin and the edges of their shirts, so it discourages them from kissing, touching, and coming closer to you, which is what they really want to do!

When somebody leaves Match.com or Chemistry.com, they ask you why you left. One box you can check is, 'I found somebody.' Between 15 and 20 percent of people check that box.

There exists no culture in which adultery is unknown, no cultural device or code that extinguishes philandering.

Once you fall for someone, their smell can be a powerful thing. Women will wear their boyfriends' T-shirts, and throughout tales in history men have held on to their lover's handkerchief.

My hypothesis is that conservative Republicans have very clear values, and when you have that, you're simply more relaxed.

For men, being too put-together implies femininity.

People have been looking for love potions since hunter-gatherer societies.

We evolved in a tropical climate where the smells of plants and flowers were all around us. We spent a lot of time in the trees with a lot of sunlight and no clothes.