There are no bright lines between leadership eras.

Very broadly speaking, the long-dominant model of autocratic leadership became less popular in the 1980s, influenced by, among other things, a new interest in culture and the popularity of books like In Search of Excellence, which advocated centralized values and decentralized decision making.

Empowerment became a watchword in the 1990s, as organizations flattened and technology put tools and information in employees' hands.

In the past decade, companies have grown more nurturing in response to a new understanding of the correlation between engagement and productivity, a greater emphasis on social responsibility, and smaller budgets with which to retain top talent. It has gone kind of like this:

The Age of Autocracy

• General Electric's Jack Welch is dubbed Neutron Jack for his propensity to get rid of employees while leaving buildings intact.
• Oracle's Larry Ellison models himself on samurai as he attacks competitors and pushes employees to the limit.
• Michael Eisner drives up Disney's stock price while driving employees crazy with his micromanagement.

The Age of Empowerment

• Howard Schultz's expansion plans for Starbucks rely on store-level employees making decisions based on knowledge of their regions.
• Oprah Winfrey is a demanding boss--but as inspiring and caring offscreen as she is onscreen.
• Meg Whitman takes over eBay, a company whose business model is all about autonomy, which requires her to trust people while insisting on integrity.

The Age of Nurture

• David Neeleman dons an apron and serves snacks to JetBlue passengers.
• Whole Foods's John Mackey contributes $100,000 annually to a fund for workers with personal struggles.
• Tony Hsieh enshrines honesty, humility, and weirdness among Zappos's core values.